WO2023161910A1

WO2023161910A1 - Apparatus for pruning young live trees

Info

Publication number: WO2023161910A1
Application number: PCT/IB2023/051831
Authority: WO
Inventors: David Marshall HUDSON
Original assignee: Hudson Strategic Limited
Priority date: 2022-02-28
Filing date: 2023-02-28
Publication date: 2023-08-31
Also published as: AU2023223665A1

Abstract

Methods and apparatus for pruning a tree that presents a plurality of tree limbs projecting at various heights from the tree trunk of the tree. The method comprises engaging a first pruning head to and about the trunk and urging the first pruning slidably up a mast. Pruning heads with a pairs of jaws with overlapping blades may be used, and the blades may have curved surfaces and rollers to follow the shape of the trunk. Further methods include using a second pruning head and co-dependently drawing said first and second pruning heads towards each other to cause at least one cutting blade of one of said pruning heads to shear through a tree limb to sever it from the trunk.

Description

APPARATUS FOR PRUNING YOUNG LIVE TREES

The present invention relates to an apparatus for pruning young live trees. In one aspect the present invention more particularly, but not exclusively, relates to an apparatus for a close prune of young live trees which may be for their first, second and/or third prune.

BACKGROUND

Trees used for the production of timber or lumber are accorded a higher value if they are straight and are substantially knot free. Knot free timber is known as clear wood. Trees that are substantially knot free, have a large collar/diameter of clear wood. Hence tree trunks with minimal knot formation are more desired for timber processing as they can be used for higher quality (and hence higher value) purposes such as veneer, timber mouldings and furniture. Knotty timber also has limited structural integrity and hence has reduced economic value in the building construction industry.

Trees can lose limbs such as branches naturally over their life. Natural pruning happens when branches do not receive enough sunlight and die. This can happen in densely populated forests. Wind may also take part in natural pruning. When this occurs, the dead branch can cause an imperfection such as a burl or knot to be generated at the surface of the trunk and this may extend some radial distance into the trunk. This reduces the clear wood diameter of the trunk.

Should a branch remain attached to the tree trunk for the duration of the life of the tree, it will also cause trunk growth imperfections such as knots.

To help reduce knot and burl formation, trees may be artificially pruned over their life. Pruning is most commonly done in a manual manner. The primary purpose of pruning is to produce clear wood. Additionally, trees such as pine and spruce trees in a densely populated forest get pruned to improve tree growth rates (height and diameter wise). Such pruning typically keeps only the upper branches (approximately the top 7m of matured tree) intact. These are located at the sunnier forest canopy and are hence most efficient to support tree growth, resulting in trees competing for sunlight with neighbouring trees. Such Silviculture practices have been developed over many years to help increase clear wood yield from a timber production forest in a safe manner.

However, manual pruning remains dangerous. It is also a skilled task that, if not done properly, can comprise the clear wood yield of a tree.

The publication Best Practice Guidelines for Silvicultural Pruning (ISBN 0-9582194- 0-0), published by Competenz (A business unit of Te Pukenga - a New Zealand Government Tertiary Education Institution) provides a guide for certain pruning procedures and techniques for the New Zealand Silviculture industry.

The Competenz guide describes several manual techniques for pruning branches from the trunk of a tree. Such involve a worker climbing a tree and using hand-held manual tools such as jacksaws or loppers to remove the lower branches of a tree. This is dangerous, physically demanding and time consuming. The advantage in the use of manual tools is that a skilled worker can ensure branch removal occurs in a way that avoids or minimises knot formation.

A common pruning fault is a coathanger. This can be caused by the branch being pruned not close to the trunk. This can lead to an increase of the size of the defect in the trunk core, hence decreasing clear wood. Another fault is collar damage where the branch is removed too close to the trunk or at the trunk itself. A quality prune creates a branch stub that will heal over with minimal knot formation.

To reduce the physical demands on a worker and to slightly speed up the pruning process, a chainsaw could also be used. The use of a chainsaw up a ladder is dangerous. A chainsaw is also heavy and also larger than loppers so it may be more restricted in its access to a branch. Chainsaws hence do not provide for a quality and consistent prune of a tree.

Silviculture operations are often recorded by approved forest managers to ensure that "best practice" is performed and resulting trees meet certain specifications. For timber to be sold as pruned timber (such as under the Pinus Radiata classification P40), the pruning quality and audit of pruning at the time of pruning has to be recorded and documented. These specifications may be contractually defined between the forest manager and contract pruners and an audit is provided for the forest owners. Following best practice will help trees be classified as "pruned". To help meet these specifications, the artificial pruning of established trees (such as Pinus Radiata) in a forest is typically done in multiple lifts of approximately 4m at two year intervals. This is desirable in order to maintain the 7m of canopy for strong growth rates. This is also desirable to help ensure the tree trunk is no larger than 170mm in diameter at the time of pruning and that the collar outside 170mm is clear wood. In accordance with the specification mentioned above, there is nothing more to be gained by pruning of larger diameter trunks as the tree will not be classified as "pruned" or "clear wood."

The number of times pruning has to occur affects the forest maintenance costs. This hence affects the financial yield of a timber production forest.

The terrain of a forest can be difficult to negotiate to get access to the trees. Especially after a number of years of growth where fallen trees and branches may hamper movement and access. This can be made even more difficult in steep terrain.

In some cases failure to prune increase the amount of deadwood remaining when the tree is felled. This causes slash which can be harmful to the environment, particularly during flooding. Regular pruning, especially second and third prunings to reduce the amount of wood in the canopy and/or leave any pruned branches to decay before the trees are felled.

Artificial pruning of trees that avoids the need for a worker climbing a ladder and manually pruning, have been developed. Self-climbing delimbers such as described in US7591292 and US10470382 are examples. Such de-limbers increase the speed at which tree branches may be removed, but they have limitations.

US10470382 discloses a hand transported delimber head with a power cable back to a ground power supply. A halfmoon cutting blade is described. As illustrated in figure 14 of the current patent specification, where reference numerals 46,70,12,72 correspond to those used in US10470382, when the blade encounters a burl indicated as 937 in figure 14, the blade 46 can deform. The deformed blade may then not cut a branch adjacent the burl at a desired distance from the trunk. Instead it may cut the limb at a distance L that may be longer than desired. As such the ability of blades to accurately follow a trunk may be reduced, and a cutting length of branches may become less accurate. Consistent quality pruning may hence not occur due to blade deformation. Hand transported delimbers need to be light enough to be able to be carried by one or two people. Yet they are still be cumbersome and slow to move between trees.

As a result of their low weight (such a 50kg) hand transported delimbers may not generate sufficient dynamic energy required for their blades to cut through branches that may be encountered in each lift. Speed of travel can increase dynamic energy. However increased speed will require increased acceleration and deceleration and as a result, increased traction (pressure) with the trunk. This can cause damage to the bark of a tree.

Due to low dynamic energy, hand transported delimbers may be more suited for the first lift (the first prune), of a young tree, when branches to be pruned are of a smaller diameter. However young trees are more susceptible to bark damage and hence sensitive to pressures applied by a hand transported delimber.

Even if more "gentle" traction is excised on a young tree, the vertical impact forces of a blade striking multiple branches during pruning can cause damage to the young tree. The impact forces are transferred to the tree trunk and this may harm the tree, particularly its roots.

During the first prune, access to tree trunk is limited by branches and the longer upward driving pruner may not have sufficient clear trunk to attached.

Furthermore, branches of some trees tend to grow in clusters of 3-6 branches extending from the trunk. A hand transported delimber striking a plurality of branches substantially simultaneously may not have sufficient dynamic energy to prune all branches.

For a Pinus Radiata tree for example, a hand transported de-limber may have a branch diameter limit of 35mm. Potentially less when multiple branches are encountered simultaneously. This equipment is hence undesirable for use in a commercial pine forest

US7591292 discloses a de-limber of live trees and teaches a light-weight delimber head. For traction it teaches the use teeth that bite into the bark of the tree and, if necessary, into the trunk. This will damage the bark and may impact tree health and growth.

WO1996019101 US discloses an apparatus for removing limbs of standing trees and teaches a telescopic mast with a delimbing device attached by a pivotal attachment to its upper end. The telescopic mast includes a foot part placed on a supportive surface adjacent the tree so as to provide support for the telescopic mast which is then aligned with the trunk. However, the system is large and difficult to operate on the digger boom, and to see the cutting blade behind the mast.

In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art.

It is an object of the present invention to provide an apparatus for pruning live trees which overcomes or at least partially ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice.

BRIEF DESCRIPTION OF THE INVENTION

In a first aspect the present invention may be said to be a tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a first pruning head able to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk so that when said first pruning head traverses up the trunk the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk, and ii. a second pruning head able to (a) capture to the trunk above or below the first pruning head and be caused to traverse along a second length of the trunk and (b) be released from the trunk, said second pruning head comprising at least one blade to locate about and in close proximity to the trunk when said second pruning head is captured to the trunk, so that when said second pruning head traverses down the trunk the blade can cut through any limbs on the second length, to sever them from the trunk in close proximity to the trunk. Preferably the first and second pruning heads are able to be caused to traverse along respective lengths of the trunk in a co-dependent manner.

Preferably the first and second pruning heads in operation, act in opposing directions to each other when cutting.

Preferably the first and second pruning heads can be caused to traverse both up the trunk and down the trunk, in opposing directions.

Preferably the first and second pruning heads can be caused to traverse both up the trunk and down the trunk, in alternating opposing directions.

Preferably the first and second pruning heads are able to be caused to traverse along respective lengths of the trunk in a co-dependent manner by a traversing mechanism.

Preferably the first and second pruning heads in operation, react from each other and in opposing directions to each other when cutting.

Preferably during cutting, no cutting forces are axially transferred to the roots of the tree.

Preferably during cutting, no cutting forces are vertically transferred to the roots of the tree.

Preferably the first and second pruning heads can be caused to traverse along their respective lengths by a traversing mechanism.

Preferably the traversing mechanism is operatively connected to both said first and second pruning heads to (a) draw the first and second running heads together and/or (b) push the first and second pruning heads apart along their respective lengths.

Preferably the traversing mechanism is operatively connected to both said first and second pruning heads to draw the first and second running heads together and to push the first and second pruning heads apart.

Preferably the traversing mechanism is operatively connected to and between both said first and second pruning heads to (a) draw the first and second running heads together and/or (b) push the first and second pruning heads apart.

Preferably the traversing mechanism resolves the force experienced by said first pruning head from its blade during cutting of a limb to an equal and opposite force applied by the blade of the second pruning head to cut the or another said limb of the trunk.

Preferably the traversing mechanism comprises at least one actuator to cause the traversing mechanism to contract to draw the first and second pruning heads together.

Preferably the traversing mechanism comprises at least one actuator to cause the traversing mechanism to expand to push the first and second pruning heads apart.

Preferably the traversing mechanism comprises at least one actuator to cause the traversing mechanism to contract to draw the first and second pruning heads together and to cause the traversing mechanism to expand to push the first and second pruning heads apart.

Preferably vertical position and position of the traversing mechanism, in use during cutting of limbs, is unconfined other than by said limbs.

Preferably vertical movement of the traversing mechanism, in use during cutting of limbs, is un-fettered other than by said limbs.

Preferably the vertical movement and/or position of the traversing mechanism, in use during cutting of limbs, is un-fettered other than by said limbs.

Preferably the traversing mechanism can cause the first and second pruning heads to traverse both up the trunk and down the trunk, in opposing directions when captured to the trunk.

Preferably the traversing mechanism comprises of at least one actuator and two connectors coupled directly or indirectly to said at least one actuator, one each coupled directly or indirectly to a respective pruning head.

Preferably the traversing mechanism comprises of two actuators a first actuator coupled directly or indirectly to the first pruning head and a second actuator coupled directly or indirectly to the second pruning head.

Preferably the first actuators is a first hydraulic ram coupled to said first pruning head and the second said actuator is a second hydraulic ram coupled to said second pruning heads, said first and second rams coupled together to react off each other.

Preferably a guide rail is provided by which, in use during cutting, the upper and lower pruning heads are guided in a vertical direction. Preferably the guide rail is provided by which, in use during cutting, the upper and lower pruning heads are guided and confined for movement to traverse in a vertical direction.

Preferably the upper and lower pruning heads are mounted off the guide to be able to slide along at least part of the guide rail.

Preferably the upper and lower pruning heads are able to slide along respective parts of the guide in a co-dependent manner and in a manner independent of the guide rail.

Preferably the upper and lower pruning heads are able to slide along respective parts of the guide rail to be moved towards and away from each other, controlled by the traversing mechanism.

Preferably the upper and lower pruning heads are able to slide along respective parts of the guide rail to be drawn towards and pushed away from each other, controlled by the traversing mechanism.

Preferably the guide rail is supported in use during cutting in a vertical orientation adjacent the trunk.

Preferably the guide rail is supported by a moveable vehicle by a boom extending from the vehicle.

Preferably the guide rail is supported at the distal end of the boom, distalmost the vehicle.

Preferably the guide rail is part of a traverser that comprises the guide rail and from which the first and second pruning heads are dependent from.

Preferably the traverser is suspended from the boom.

Preferably the traverser is freely suspended from the boom when the first and second pruning heads are not engaged to said trunk.

Preferably the traversers comprises a first traveller coupled to said first pruning head and a second traveller coupled to said second pruning head, each traveller connected to said guide rail in a sliding manner to allow their travel along at least part of said guide rail.

Preferably each traveller comprises of a carriage coupled to said guide rail for sliding along said guide rail. Preferably said traversing mechanism and said upper and lower pruning heads are able to move in directions parallel said guide rail.

Preferably the guide rail is an elongate straight rigid guide rail.

Preferably each carriage comprises of rollers and/or skids to facilitate sliding over the guide rail.

Preferably a base slide is provided, in sliding engagement to said guide rail and intermediate of the first and second rams, the first and second rams connected to said base slide to allow the first and second rams to react off each other.

Preferably said first ram is a lower ram and the second ram is an upper more ram, the upper more ram connected to said base slide at a location below the location at where the lower ram is connected to the base slide.

Preferably the upper ram is also connected to the upper more of said travellers.

Preferably the lower ram is also connected to the lower more of said travellers.

Preferably during cutting, no cutting forces are transferred to the guide rail.

Preferably each pruning head comprises of a plurality of blades to each locate against a part of the circumferential surface of the trunk, said plurality of blades in concert to locate against a substantial part of the circumferential surface of the trunk, each blade independently mounted by a respective arm that allows its respective blade to move radially relative to the tree trunk independently of the other blades, said blades each have a primary cutter that when said pruning head travels in a direction along the tree trunk, can drive through limbs to cut them from the trunk in close proximity to the trunk.

Preferably the pruning head comprises at least 3 blades to each locate against the trunk at the circumference of a sector of the trunk and in concert locate against a substantial part of the circumferential surface of the trunk.

Preferably each blade can each locate directly against the tree trunk.

Preferably each blade can slide over the tree trunk as the pruning head travels up and/or down the trunk.

Preferably each blade is radially positioned to cut limbs from the trunk at a predetermined distance from the trunk, guided by the circumferential surface of the trunk adjacent the blade. Preferably the pruning head comprises at least 6 blades to each locate against the trunk at the circumference of a sector of the trunk, said at least 6 blades in concert able to locate against a substantial part of the circumferential surface of the trunk, each blade supported by a respective arm to allow the blades to move radially towards and away from the elongate axis, so as to allow each blade to follow the circumferential surface of the trunk in use independently of each other, as the pruning head travels up and/or and down along the trunk.

Preferably the pruning head comprises at least 6 blades to each locate against the trunk at the circumference of a sector of the trunk, said at least 6 blades in concert able to locate against a substantial part of the circumferential surface of the trunk, each blade supported by a respective arm to allow the blades to move radially towards and away from the elongate axis, so as to allow each blade to follow the circumferential surface of the trunk in use independently of each other, as the pruning head travels up and/or down along the trunk, so that when one blade is caused to move radially outwardly by the circumferential surface of the trunk, the primary cutter of the other blades are not caused to move radially outwardly by said one blade.

Preferably each blade can move radially relative the trunk independently of the other blades so that when one blade is caused to move radially outwardly by the circumferential surface of the trunk, the other blades are not caused to separate from the trunk.

Preferably each blade can move radially relative the trunk independently of the other blades so that when one blade is caused to move radially outwardly by the circumferential surface of the trunk, the other blades are not caused to separate from the trunk by the one blade.

Preferably each blade can move radially relative the trunk independently of the other blades so that when one blade is caused to move radially outwardly by the circumferential surface of the trunk, the primary cutter of or the other blades are not move radially outwardly from the trunk.

Preferably each arm is mounted to a chassis of the pruning head in a pivotal manner about a rotational axis to provide for the radial movement of each blade. Preferably each arm is mounted to a chassis of the pruning head in a pivotal manner about a respective rotational axis that is perpendicular to the elongate axis and parallel a tangent of the trunk immediately adjacent the arm, when in use.

Preferably each arm is an elongate arm that extends in a direction substantially parallel to the elongate axis of the trunk when in use, from the chassis at a first end of the arm where the arm is mounted to the chassis to a distal end of the arm at where a respective blade is mounted.

Preferably each arm is elongate and extends in its elongate direction from where it is mounted to the chassis in a direction so that the cutting force of the blade causes a tensile or compression force in the arm, transferred from the arm to the chassis at where the arm is mounted to the chassis.

Preferably the pruning head comprises at least 2 pruning units each comprising a respective chassis and at least one arm.

Preferably each said pruning unit comprises two arms mounted to each said chassis, each arm having a respective blade mounted to it.

Preferably each blade (a) can move radially relative the trunk by rotation about the rotational axis of its respective arm and (b) is mounted to its respective arm in a swivelling manner to allow the blade to rotate about an axis substantially parallel the elongate axis of the trunk when in use.

Preferably a notional line between rotational axis of the arm and distal end of the arm at where the blade is mounted is substantially parallel the elongate axis of the trunk.

Preferably said two arms per chassis share a common pivot axis at where they are mounted to the chassis.

Preferably each arm has a respective blade mounted to it in a swivelling manner allowing the blade to rotate in use around an axis parallel the elongate direction of the trunk.

Preferably the arm is confined in movement relative to the chassis it is mounted to only be able to rotate relative the chassis about its rotational axis.

Preferably each blade is confined in movement relative the arm it is mounted to only be able to rotate relative the arm about a swivel axis parallel the elongate axis of the trunk. Preferably each arm is biased towards said trunk in use.

Preferably each arm is biased towards said trunk, in use, by a spring.

Preferably the pruning head is configured like a jaw, able to move between an open condition and a more closed condition, wherein in the open condition the pruning head can be engaged and removed from the trunk and when in the more closed condition the pruning head is captured to the trunk.

Preferably the pruning head is able to reconfigure between an open condition and a more closed condition, wherein in the open condition the pruning head can be engaged and removed from the trunk and when in the more closed condition the pruning head is captured to the trunk.

Preferably the trees to be pruned by the pruning apparatus are Pinus Radiata trees.

Preferably the limbs to be cut from the trunk are up to 60mm in diameter.

Preferably the pruning head is of a jaw configuration and is at least partially circular, with an opening able to be created and closed, configured to receive a trunk.

Preferably, each blade has a primary cutter presented to cut limbs when the pruning head travels up the trunk and a secondary cutter presented to cut limb stubs when the pruning head travels down the trunk.

Preferably each blade has opposed cutting ends wherein said primary cutter is defined at a first of said opposed cutting ends and the secondary cutter is defined and the other of said opposed cutting ends.

Preferably the secondary cutter is configured to cut closer to the trunk than the primary cutter.

Preferably the secondary cutter is configured to cut the limb from the trunk to leave a limb stub projecting a length from the trunk and the secondary cutter is configured to shave the limb stub to reduce its length projecting from the trunk.

Preferably the blade comprises a trunk contact surface that extends between the primary and secondary cutters.

Preferably each blade comprises a trunk contact surface configured to engage with the surface of a trunk in use, the cutters having cutting edges being at a predetermined distance from the trunk contact surface to create a predetermined limb stump length.

Preferably each blade comprises a trunk contact surface configured to engage with the surface of a trunk in use, the primary having a cutting edge being at a predetermined distance from the trunk contact surface to cut each limb to a predetermined limb stump length.

Preferably the pruning apparatus may have blades presented for cutting limb from the trunk when the pruning head travels upwardly and may have blades presented for cutting limb stumps when the pruning head travels downwardly.

Preferably the blades presented for cutting limb stumps cut closer to the trunk than the blades presented for cutting the limbs.

Preferably the plurality of blades each locate directly against a part of the circumferential surface of the trunk to be able to slide along the trunk over the trunk.

Preferably the plurality of blades each locate indirectly against a part of the circumferential surface of the trunk in a manner to be able to slide along the trunk guided by the trunk.

Preferably said close proximity to the trunk is less than 10mm and preferably less than 5mm and preferably between 2 and 5 mm and preferably around 3mm.

Preferably said secondary cutter will shave the limb stub to a length from the trunk less than 10mm and preferably less than 5mm and preferably between 2 and 5 mm and preferably around 3mm.

Preferably said primary cutter will cut the limb to a length from the trunk less than 10mm and preferably less than 5mm and preferably between 2 and 5 mm and preferably around 3mm.

Preferably the boom is moveably attached to a vehicle to allow relocation of the traverser, carrying the pruning head, from one tree to another tree without the vehicle needing to move.

Preferably there are two booms extending from the vehicle each able to move independently relative the vehicle and each carrying a respective traverser with pruning heads, each capable of operating independently of each other to allow pruning of two trees to occur from one ground position of the vehicle. Preferably there are two booms extending from the vehicle each able to move independently of each other relative the vehicle and be operated to allow a first boom to locate its respective traverser and pruning heads to a first tree and be performing pruning on that first tree whilst the second boom is relocating its respective traverser and pruning head from a second tree to a third tree.

Preferably the pruning apparatus may also be referred to as a mobile tree pruner.

Preferably the tree to be pruned is a Pinus Radiata tree.

Preferably the tree to be pruned presents a plurality of limbs projecting from the trunk at a plurality of heights along the trunk.

Preferably the tree to be pruned presents a 5 limbs projecting from the trunk at a plurality of heights along the trunk.

Preferably the plurality of limbs comprises of at least one limb located above another limb.

Preferably the plurality of limbs comprises of at least one limb located and spaced apart at least 500mm above another limb.

A method of pruning a tree that presents a plurality of tree limbs projecting at various heights from the tree trunk of the tree, the method comprising: engaging (preferably capturing) a first pruning head and a second pruning head to and about the trunk at spaced apart locations to position at least two limbs intermediate of said first and second pruning head, the first pruning head comprising at least one cutting blade presented for use to cut through tree limbs, co-dependently drawing said first and second pruning heads towards each other to cause said at least one cutting blade to shear through a tree limb to sever it from the trunk.

Preferably said first and second pruning heads are co-dependently drawn towards each other to cause said at least one cutting blade of said first pruning head to shear through successive tree limbs to sever them from the trunk.

Preferably the second pruning head comprises at least one cutting blade presented for use to cut through tree limbs.

Preferably said first and second pruning heads are co-dependently drawn towards each other to cause said at least one cutting blade of said first pruning head and said second pruning head to shear through successive tree limbs to sever them from the trunk.

Preferably said first and second pruning heads are co-dependently drawn towards each other to cause said at least one cutting blade of said first pruning head and said second pruning head to iteratively shear through successive tree limbs to sever them from the trunk.

Preferably said first and second pruning heads are co-dependently drawn towards each other by a traversing mechanism.

Preferably said second pruning head also comprises at least one cutting blade presented for use to cut through tree limbs.

Preferably said first pruning head is a lower more pruning head that before being drawn towards the second pruning head is engaged to the trunk spaced apart from and below the second pruning head.

Preferably said first pruning head is an upper more pruning head that before being drawn towards the second pruning head is engaged to the trunk spaced apart from and above the second pruning head.

Preferably, before being drawn together, the first pruning head is proximate more a first of said limbs and the second pruning head is proximate more a second of said limbs that is vertically spaced apart from said first of said limbs.

Preferably, before being drawn together, the first pruning head is proximate more a first of said limbs and the second pruning head is proximate more a second of said limbs that is vertically spaced apart from said first of said limbs, the method comprising drawing said pruning heads together so that a reaction force is provided from said second pruning head by said second of said limbs to said first pruning heads to cause said blade to cut into said first of said limbs.

Preferably said first and second pruning heads are co-dependently drawn towards each other wherein the first pruning head comprises said cutting blades and said second pruning head comprises a stop (or not cutting blades) to prevent the second pruning head from severing through limbs. In a further aspect the present invention may be said to be a method of pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said method comprising: iii. capturing a first pruning head to the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk, iv. capturing a second pruning head to the trunk above the first pruning head, said second pruning head comprising at least one blade to locate about and in close proximity to the trunk when said second pruning head is captured to the trunk, v. causing said first and second pruning heads to move co-dependently in an opposed direction relative to each other in a direction parallel the trunk of the tree so that when said first pruning head encounters a said limb it cuts through said limb when said second pruning head encounters one or more other of said limbs.

In a further aspect the present invention may be said to be a method of pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said method comprising: i. capturing a first pruning head to the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk, ii. capturing a second pruning head to the trunk above the first pruning head, said second pruning head comprising at least one blade to locate about and in close proximity to the trunk when said second pruning head is captured to the trunk, iii. causing said first and second pruning heads to move co-dependently in an opposed direction relative to each other in a direction parallel the trunk of the tree to each and iteratively cut through limbs of the trunk in an upward and downward direction.

In a further aspect the present invention may be said to be a tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a first pruning head able to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk so that when said first pruning head is captured to the trunk and traverses the first length of the trunk, the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk, and ii. a second pruning head able to (a) capture to the trunk at a location spaced from the first pruning head and (b) be released from the trunk, iii. a traversing mechanism to push and/or pull the first and second pruning heads co-dependently away and/or towards each other in a manner so that said first pruning head acts, in traversing said first length, cuts through any limbs on the first length, in reaction from said second pruning head being located against another of said limbs.

Preferably the first pruning head is able to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk so that when said first pruning head traverses up the trunk the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk.

Preferably the second pruning head is able to (a) capture to the trunk above or below the first pruning head and be caused to traverse along a second length of the trunk and (b) be released from the trunk, said second pruning head comprising at least one blade to locate about and in close proximity to the trunk when said second pruning head is captured to the trunk, so that when said second pruning head traverses down the trunk the blade can cut through any limbs on the second length, to sever them from the trunk in close proximity to the trunk.

In a further aspect the present invention may be said to be a tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a traverser comprising a foot configured to sit on the ground near the trunk and a distal end extending vertically substantially parallel to the trunk, the traverser having a first portion connected the foot, and a second portion slidably connected to the first portion, ii. a first pruning head mounted to second portion of the traverser and configured to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk so that when said first pruning head traverses up the trunk the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk wherein the second portion is configured to extend upwards relative to the first portion, to traverse the first pruning head up the tree, pruning the tree.

The use of an extending traverser allows the machinery at the top of the traverser to be minimised making it easier to place the traverser against the tree without branches getting in the way or the operator's vision being obscured. This results in the pruning head being the first component to move up the tree, making pruning of trees, particularly second and third prunings easier.

Optionally the second portion surrounds, or fits over, the first portion. This protects the drive of the traverser as well as creating a compact traverser and simple mechanism.

Optionally the first pruning head is mounted at or near the top of the second portion.

Optionally further comprising a support head configured to capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first support head supporting the traverser aligning to the trunk. The second or support head helps to guide the second portion on its extension and maintain the angle of the second portion relative to the tree to improve pruning. Optionally comprising an actuator for extending the second portion, the actuator located at or near the foot.

Optionally the second portion is about 4 meters long. The length may be adjusted depending on the required pruning height.

Optionally the first pruning head is mounted to the outside surface of the traverser.

Optionally the traverser extends to substantially twice its non-extended height. A set of differently sized traversers may be used to achieve different pruning height requirements.

Optionally the traverser is configured to attach to a boom at or near the foot of the traverser. This makes locating the traverser easier as the boom does not need to move through the branches.

Optionally the traverser comprises a chain drive, the second portion mounted to the chain drive such that movement of the chain drive extends the traverser. Optionally two chain drives are used, each chain drive located on one side of the traverser. Optionally the traverser is a beam, such as an I-beam with a front face and a central member. Optionally the central member separates the two chain drives.

Optionally the foot comprises a base plate, optionally wherein the base plate is planar.

Optionally the first pruning head is able to be caused to traverse along a length of the trunk. Optionally comprising a trunk grabbing or support head able to (a) capture to the trunk at a location spaced from the first pruning head and (b) be released from the trunk. Optionally the support head is a second pruning head. Optionally the pruning heads are able to be caused to traverse both up and down the traverser. Optionally during cutting, substantially no cutting forces are transferred to the trunk of the tree. Optionally the traverser resolves the force experienced by said first pruning head from its blade during cutting of a limb to an equal and opposite force applied by or at the foot. Optionally the traverser comprises at least one actuator configured to move the pruning head along the traverser. Optionally only pruning and/or support heads extend from the traverser. This makes positioning the traverser easier. Optionally a guide rail is provided which, in use during cutting, the upper and lower pruning heads are guided in a vertical direction. Optionally the first pruning head is mounted off the guide to be able to slide along at least part of the guide rail.

In a further aspect the present invention may be said to be a tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a traverser comprising a foot configured to sit on the ground near the trunk and a distal end extending vertically substantially parallel to the trunk, ii. a first pruning head slidably mounted to the traverser and configured to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk so that when said first pruning head traverses up the trunk the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk.

The use of a foot and a pruning head on the traverser ensures all, or at least a majority of the forces are translated to the foot instead of the trunk reducing bark damage. This improves pruning quality.

Optionally the traverser is configured to attach to a boom at or near the foot of the traverser. Optionally the traverser has the features described in any one of the other aspects.

Optionally the first pruning head is configured to move from a position at or near the foot of the traverser, to a position at or near the distal end of the traverser. At or near may be within 1 m or 0.5m or substantially ground level so as to provide maximum range.

Optionally the first pruning head is mounted to a traveller, the traveller slidably mounted to the traverser. The traverser or carriage provides a connection to the traverser which is protected from and resilient to branch impacts. Optionally the traverser comprises an additional blade above the traveller to protect the traveller from branches and/or other impacts.

Optionally the traverser comprises a shield configured to protect the upper end of the traverser. Optionally the traverser comprises a chain drive, the traveller mounted to the chain drive such that movement of the chain drive moves the traveller along the traverser. Optionally the chain drive is driven by an actuator to move the traveller.

Optionally the foot comprises a base plate, optionally wherein the base plate is planar. Optionally the foot is rotatably connected to the boom and configured to rotate to allow alignment of the traverser and the trunk. The foot provides a secure placement for the traverser and may be adapted to ensure a solid grounding on a range of ground conditions.

In a further aspect the present invention may be said to be a tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a first pruning head able to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising a first and second pairs of jaws, each jaw comprising a blade to locate about and in close proximity to the trunk so that when said first pruning head is captured to the trunk and traverses the first length of the trunk, the blades can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk, wherein the first and second pairs of jaws are offset and angled toward one another so as to surround the trunk when in a closed position.

The pruning head is configured to ensure a close cut, with minimal branch damage, by having two pairs of offset jaws so that they overlap and avoid missed branches at the edges of the attached blades.

Optionally the blades are arcuate or curved so as to follow the curve of the tree.

Optionally for each pair of jaws, the jaws are linked or joined such that movement of a first jaw will move the second jaw.

Optionally the jaws are connected so that rotation of a first jaw urges rotation of a second jaw. Linking the jaws ensures that they close equally to better surround the tree.

Optionally the first and second jaw have teeth that engage one another.

Optionally the jaws are supported by a frame attached to the traveller. Optionally the face of each blade is configured to locate a set distance from the trunk of the tree. Optionally this distance is controlled by a pruning spacer. Optionally the pruning spacer is a roller. Optionally the pruning spacer or roller is configured to slide over the roller as the pruning head travels up and/or down the trunk. Optionally the pruning spacer or roller is located directly against the tree trunk. Optionally the pruning spacer or roller is softly closed against the tree trunk. Optionally this uses a hydraulic actuator at soft pressure. Optionally each pair of blades has some play, such that each of the blades can move radially relative the trunk independently of the other blades so that when one blade is caused to move radially outwardly by the circumferential surface of the trunk, the other blades are not caused to separate from the trunk. Optionally each jaw is mounted to a chassis of the pruning head in a pivotal manner about a rotational axis. Optionally the jaws are vertically separated. Optionally the jaws are connected to the same traveller. Optionally the pruning head is able to reconfigure between an open condition and a more closed condition, wherein in the open condition the pruning head can be engaged and removed from the trunk and when in the more closed condition the pruning head is captured to the trunk. Optionally in the closed condition each set of jaws has a substantially oval mouth.

In a further aspect the present invention may be said to be a blade for a tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said blade comprising:

An arcuate surface configured to face the trunk; and

A cutting edge configured to cut limbs from the trunk, the cutting edge having a point.

The pointed cutting edge on an arcuate surface was found to improve the repeated cutting ability of the blade, reducing damage to the tree during pruning.

Optionally the point is centred on the arcuate surface.

Optionally the cutting edge slopes away from the point at an angle of between 20 and 80 degrees, between 30 and 70 degrees, between 40 and 60 degrees, between 50 and 60 degrees, or substantially 55 degrees. Optionally the arcuate surface has first surface with a concave curve and wing surfaces with convex curves.

Optionally the arcuate surface has first surface with a concave curve and wing surfaces with convex curves.

Optionally the cutting edge is angled at substantially 45 degrees.

Optionally comprising a position guide configured to space the blade away from the trunk in use.

Optionally comprising an opening in the arcuate surface, wherein the position guide is configured to pass through the opening.

Optionally the position guide is a roller configured to contact the trunk of the tree in use.

Optionally the roller has a variable diameter along the width of the blade, optionally wherein the diameter reduces around a midpoint of the roller.

Optionally the roller extends across at least 40, 50, 60 or 70 percent of the width of the blade.

Optionally the roller is connected to a frame supported by the blade.

Optionally the cutting edge of the blade is serrated.

Optionally the serrations are less than 10mm, less than 5mm, or less than 1 mm high.

Optionally the serrations are greater than 20mm, than 10mm, or greater than 5mm long.

In a further aspect the present invention may be said to be a pruning head comprising a pair of arms, each arm connected to a blade as described, the arms configured to move between an open position in which the blades are open to allow the blades to surround a trunk, and a closed position in which the blades closely surround the trunk.

In a further aspect the present invention may be said to be a method of pruning a tree comprising one or more of the tree pruning apparatus described herein. The method comprising locating the traverser at or near the trunk of the tree to be pruned, connect the pruning head to the trunk and urging the pruning head up the trunk to prune the tree. In a further aspect the present invention may be said to be a method of pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said method comprising: iv. capturing a first pruning head to the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk, v. causing said first pruning heads to slidably move along a traverser in a direction parallel the trunk of the tree to iteratively cut through limbs of the trunk in an upward direction.

In a further aspect the present invention may be said to be a tree pruning apparatus as in any one or more of the other aspects comprising at least one blade as described. Optionally any one or more features of the tree pruning apparatus, the pruning head and/or the blade as described may be combined or interchanged.

As used herein the term "and/or" means "and" or "or", or both.

As used herein "(s)" following a noun means the plural and/or singular forms of the noun.

The term "comprising" as used in this specification and claims means "consisting at least in part of". When interpreting statements in this specification and claims which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner.

The entire disclosures of all applications, patents and publications, cited above and below, if any, are hereby incorporated by reference.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.) BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described by way of example only and with reference to the drawings in which:

Figure 1 a is a perspective view of a pruner showing a multi limb configuration of the pruner, each limb having two pruning head, one shown in an elevated condition and another pruning head in a lowered condition,

Figure 1 b is an alternative and perspective view of figure 1 a,

Figure 1 c shows the pruner where for one limb the pruning heads are in a distal most relationship to each other and for the other limb the pruning heads have been drawn together,

Figure 2a is a perspective close-up view a lower pruner head of a preferred form of the present invention in the open condition,

Figure 2b shows a close up view of a pruning head in its closed condition,

Figure 3 is a close-up perspective view of an upper pruning head of one limb of the pruner,

Figure 4a shows the upper and low pruning head of one limb and the traverser that each is supported by,

Figure 4b shows a simplified view of the traverser to help illustrate how the forces are resolved,

Figure 4c shows a few more details of the simplified view of figure 4b,

Figures 4d-g show an example of how the pruning heads may travel during the first past of pruning the tree, where the pruning heads travel towards each other,

Figure 5 shows a close up of an upper pruning head in an open condition,

Figure 6 shows a close up view of a pruning unit of a lower pruning head, Figure 7 shows a close up of a lower pruning head in an open condition

Figure 8a shows an exploded view of a pruning unit of a lower pruning head to show the assembly configuration,

Figure 8b shows two arms of a pruning unit,

Figure 9 shows a lower pruning head and with one pruning unit shown in a partially exploded view, Figure 10 shows a close-up perspective view of a plurality of blades each supported by respective arm independently of each other,

Figure 1 1 is a schematic view of a cutting blade adjacent a tree stump,

Figures 12 and13 show the cutting blade in an up stroke and down stroke respectively cutting a branch from a tree trunk,

Figure 14 (prior art) illustrates a prior art pruner showing features to illustrate disadvantages inherent in such prior art pruning apparatus as hereinbefore described,

Figure 15 shows the traverser with the upper and lower pruning heads in a separated condition,

Figure 16 shows the traverser with the upper and lower pruning heads in a separated condition and with the guide rail not shown, in order to reveal more of the traversing mechanism,

Figure 17 shows the traverser with the upper and lower pruning heads in a proximal condition,

Figure 18 shows the traverser with the upper and lower pruning heads in a proximal condition and with the guide rail not shown, in order to reveal more of the traversing mechanism,

Figure 19 is a perspective view of an alternative pruner showing a pruning head attached to a traverser,

Figure 20 shows a) a perspective of the traverser and pruning head of Figure 19 and b) detail around the foot of the traverser,

Figure 21 shows a) perspective and b) side views of the traverser and pruning head as shown in Figure 19, c) a side view of the connection of the foot traverser and pruning head,

Figure 22 shows a) horizontal and b) vertical cutaways of the traverser with the pruning head near the foot so as to show the connection of the carriage to the traverser,

Figure 23 shows a) perspective, b) front and c) plan views of a pruning head,

Figure 24 shows a) perspective and b) plan views of a pair of blades on the pruning head of Figure 23,

Figure 25 shows a) perspective b) plan, c) front views of a blade and roller arrangement and d) a side view of a blade, Figure 26 shows a perspective view of an alternative pruner with a pruning head on an extending mast,

Figure 27 shows the mast from Figure 26,

Figure 28 shows a perspective view of the mast of Figure 27 from below, and

Figure 29 shows a) perspective view of a pruner head attached to the mast and closed around a tree and b) plan and c) perspective views of the pruner head without the tree present.

DETAILED DESCRIPTION

With reference to the above drawings, in which similar features are generally indicated by similar numerals, a first example of a tree pruner is shown in figure 1 a.

The pruner 1 is configured to prune branches or limbs 2 off of a trunk 3 of a tree 4. The tree 4 to be pruned by the pruner 1 is alive, in situ and upright extending out of the ground 6.

The tree 4 has a base 7 nearest the ground 6, and an upper region 8 distal from the ground 6 and base 7. The tree may be a pine tree or spruce tree for example. The tree is preferably a young tree and the pruner is used to perform the first prune of the tree. The pruner may also be used is used to perform the second prune of the tree. The pruner may also be used is used to perform the third prune of the tree. 1 . The first prune may occur of a height range of 0 -3m or 0-4m. The second prune at a height range of around 3-6m or 4-8m and the third prune at a range of 6-9m or 8-12m.

The tree may for example be a Pinus Radiata variety of pine tree. These can grow relatively straight if appropriate silviculture is exercised. The tree 4 may hence have a notionally straight elongate axis 5 extending centrally along the trunk. This axis is usually vertical for a live tree.

The pruner 1 may comprise of a vehicle 9 which may house an operator (not shown) in an operator cage 10. The operator is safely protected from any detritus created during the pruning process by the operator cage 10. The vehicle can propel itself over the ground, including on inclined terrain. The vehicle may have traction tracks for such purposes.

The pruner 1 may comprise a boom 12 that is supported from the vehicle 9. In figures 1 a and 1 b two booms are shown. Each boom is shown coupled to the vehicle in a rotational manner. Two axes of rotation are preferably provided. This allows the boom 12 to lift and lower and to swing horizontally relative the vehicle and/or ground. This allows the boom to move relative the ground on which the vehicle is positioned. The boom 12 may also be telescopic. This allows the distal end of the boom to be positioned within a relatively large envelope of travel. This is a 3 dimensional envelope.

In figures 1 a and 1 b a preferred from of the pruner 1 is shown having 2 limbs comprising of 2 booms. The two booms are able to move independently of each other relative to the vehicle. The movement is preferably controlled by the operator. One or more actuators may be used for such control. These may be hydraulic actuators. In some forms the pruner may only have one limb and hence only one boom.

The provision of two booms allows pruning work on two adjacent trees to occur independently, from one ground position of the vehicle. The advantages of this are described below.

The vehicle 9 is capable of operating in rugged environments and step terrain.

The, or each, limb of the pruner 1 may also comprise of a pruning head 200 having a plurality of blades positioned to cut through limbs of the tree to remove them from the tree trunk. Details of these features will be set out in more detail below, after the following brief introduction. In a preferred form each limb has two pruning heads 200A and 200B the former being a lower pruning head and the latter an upper pruning head. These are attached to a traverser 1500 that is supported (preferably suspended) from a distal end of a respective boom 12.

The traverser 1500 is preferably suspended from the distal end of a boom so that in can hang below the end of the boom 12, preferably in appropriate alignment with the tree trunk ready for use. A swivel connection 1501 may be provided intermediate of the boom and traverser 1500 so as to allow the traverser (and its associated upper and lower pruning heads) to rotate and swing relative to the boom. This pivotal movement (together with the boom's range of motion relative to the ground) allows the traverser 1500 to be positioned in appropriate alignment with the trunk to allow the pruning heads 200A, 200B of each limb to each become located adjacent the tree to then engage the trunk. This can be achieved by ensuring the vehicle 9 is parked in an appreciate location adjacent a tree. The vehicle 9 itself does not require accurate positioning to ensure the traverser can locate adjacent the tree trunk, so long as the vehicle is proximate a tree. The traverser 1500 will naturally suspend itself from the boom so that its guide rail 1560 is in a vertical orientation which is preferably parallel with a tree 4 to be pruned that is growing upright.

Once each pruning head 200A, 200B is located to a tree trunk, the pruning heads can be caused to traverse travel along the guide rail 1560 by a traversing mechanism that will be described. Such traversing will cause the pruning heads move along part of the trunk in opposed directions to each other to effect a cutting of the branches. After pruning a tree, the pruning heads can then be removed from the trunk and manoeuvred to the next tree for pruning.

Hydraulic, pneumatic and/or electrical power is supplied to the pruning heads for the purposes powering components of the pruning head that will hereinafter be described. Likewise, such power is provided for the traversing mechanism of the traverser. The power may be transferred via an umbilical such as a power cable. The umbilical extends from the vehicle 9 to the pruning heads and can travel with the pruning heads 200A, 200B as the move along the tree trunk 3.

Preferably the vehicle 9 supplies power to the pruning heads via the umbilical and utilising a hydraulic accumulator 1 1.

In a preferred form the function of each pruning head is to close prune trunks, for the production of a large clear wood collar by appropriately removing limbs from the trunk. If not appropriately cut and closely to the trunk, substantial knots or burls can develop in the trunk at where the limbs have been removed. As will hereinafter be described the use of independent blade suspension aids the accurate and consistent pruning of limbs from a trunk. The use of cutting blades, that are preferably operational in both the upward and downward movement of the pruning head, but optionally operational in a single direction, may also facilitate this. Each pruning head 200 may cut limbs 2 or limb stubs during both the upward movement and downward movement of the pruning head 200 along the trunk 3. This will be described in more detail below.

Each pruning head 200 can configure between an open condition and a closed condition. In an open condition (as for example shown in figure 2a and figure 3) the pruning head 200 is able to receive a trunk 3 and be released from the trunk and in a closed condition (as for example shown in figure 1 c and 2b) the pruning head 200 extends sufficiently about and securely locates and retains to the trunk 3. In the closed condition the blades are presented in their condition for cutting.

The pruning head 200 comprises a chassis or a plurality of chassis. It may comprise of a base or base chassis 201 that may support a number of features of the pruning head 200. The base is preferably that part of the pruning head that facilitates the holding and traversing of the pruning head with the traversing beam 1500.

From the base 201 there is dependent one or more pruning units 202 as shown in Figure 2a and 3. In a preferred from there are 3 pruning units 202A-C. The units are connected to each other using a hinge 204 so that the units can move relative to each other and assume open and closed condition of the pruning head. Unit 202A is preferably secured to or part of the base 201. Unit 202B is dependent from unit 202A using a hinge on one side of unit 202A. Unit 202C is dependent on the other side, using a hinge. The hinge defines a pivotal axis YY (shown in Figure 5) that is substantially parallel the elongate direction 5 of the tree trunk, in use.

A hinge actuator 203 for one or each hinge may be used to control the rotation of the units relative each other. This may be controlled directly by the operator or by an automated process. The ability of the units 202 to pivot allows the pruning head to move between the open and closed conditions. In a jaw like manner for example. In an open condition the units 202B and 202C are more separated from each other than when in the closed condition where the units 202B and 202C are more proximate each other at the split 606. When the traverser is positioned near a tree 4 the units 202B and 202C can separate to create a mouth opening for the trunk of the tree to pass through and to then become captured to the pruning head when the units 202b and 202C are caused to move towards each other by the actuators 203. In the closed condition the pruning head is captured to the trunk and cannot laterally come off the trunk. The mouth 606 is more closed in this closed condition and of a size slightly larger than the diameter of the trunk so as to limit contact with the trunk and/or bark damage. The cutting edge of the blades of the mouth may have a diameter that may be 5mm, 10mm 12mm, 15mm or 20mm larger than the trunk so as to allow pruning without bark damage. Other features of the jaws, such as rollers may contact the trunk for support.

The actuators can be controlled to maintain the closed condition during tree pruning. The actuators can cause pressure of the pruning head to be applied to the trunk for the proposes of providing contact of the rollers 1505 of the pruning head with the trunk. The rollers 1505 are preferably idle rollers and can be held against the trunk provided for guiding each pruning head along the trunk. They preferably are not forced against the trunk to an extent to cause adverse damage to the trunk. They provide no motive traction to the trunk and hence little of no shear forces are experienced by the trunk from the rollers. In the open position, the traverser 1500 with the upper and lower pruning heads attached is preferably balanced and suspended from a universal joint or swivel 1501 such that the guide rail 1560 is vertical and in alignment with young vertical tree trunks.

Each unit 202A-C comprises of a chassis 608. The chassis is generally elongate in the direction parallel the axis 5 when in use. Each chassis provides support to other components of its respective unit. The hinges 204 are preferably connected to respective chassis' such as by the use of threaded fasteners 609. The base 201 is preferably engaged to the chassis of the unit 202a. Limbs 2 of a tree are cut using a plurality of blades 220 of the pruning head.

Optionally the blades are each independently supported by and presented from a respective chassis. This allows for more consistent pruning of trees to occur.

Each independent blade is supported by its own dedicated linkage (such as the arm 660 herein after described). Each pruning head may have three or more blades so supported independently. Optionally there are size of such blades per pruning head. The blades are able to be independently positioned about circumference of a sector of the trunk. Where there are size blades each sector is substantially 1/6 of the circumference of the trunk. Optionally all blades in concert are able to locate about substantially the full circumference of the trunk.

The blades are preferably supported by a respective said chassis 610 about a rotational axis parallel the elongate axis and/or a rotational axis perpendicular the elongate axis. This articulation allows each blade to independently follow the varying surface profile of the trunk as the pruning head travels along the trunk.

Each blade 220 is preferably dependent from a chassis 610 by a respective arm or jaw 660. Each blade is preferably supported at a distal end 671 of a respective arm 660. Each blade 220 is optionally secured to the arm using a bolt or axle 663 that allows the blade to rotate relative to the arm about an axis, that when the pruning head is captured to a trunk, extends substantially parallel the axis 5. This allows the blade some degree of freedom of movement relative to the chassis and/or arm. Preferably the arm is itself supported by the chassis at the opposite distal end of the arm 660. Optionally each arm is attached to a chassis in a rotational manner at pivot axis 667 with the use of a bolt or axle 668 for example. The axis 667 is preferably perpendicular to the axis 5 and parallel a tangent of the trunk 4, when in use. Preferably two of said arms 660 are so supported by a chassis. So each chassis 608 may supports two arms each in turn supporting a respective blade. The provision of the axis 667 allows the blades to move radially in and out relative the trunk.

As can be seen the shape and configuration of the chassis and its respective arms allows for two arms to be disposed at opposed lateral sides of the chassis and at a radially outward part of the chassis. A single bolt or axle 668 may be used to secure the two arms to a chassis. The axis 667 is preferably perpendicular to the axis 5 in use. It is optionally parallel the axis of the wheels or sprockets herein before described. This allows the blade at the opposite end of the arm to the pivot 668 to move substantially radially in and out relative to the trunk in use and independent of the other blades. The arm may be substantially elongate and positions the blade at the opposite end to where the pivot is provided so that the radial movement is accompanied by negligible blade rotation about the axis 667 thereby ensuring the blade angle relative the trunk remains substantially constant. The position of the pivot axis 667 well away from where the blade is subjected to cutting forces also means a favourable angle of force can be transmitted from the chassis (by virtue of its momentum and the traction forces from the traction belt) to the blade. This favourable angle helps reduce bending moments in components of the pruning head helping increase the cut force of the cutters applied to each limb.

The range of rotational movement of the arm relative the chassis may be limited by a slot and pin arrangement. A pin 675 of the arm may be registered in a slot 676 of the chassis the slot defining end stops that limit the range of rotation of the arm relative to the chassis. The pin may be a bolt. The pin or bolt may help retain the arm, within its rotational limits, to the chassis. Each arm has its own pin so that the arms can rotate about its respective axis 667 independent of the other arms. Hence allowing the blades to independently move radially inwards and outwards relative the trunk and independent of each other.

Optionally each blade 220 comprises a contact surface 227 configured to engage with or close to and slide over the surface of a trunk 4 in use. Each blade preferably has an arcuate or curved surface of a radius that is in close proximity, at least in part, to the radius of trees to be pruned.

The blades 220 of the pruning head 200 may at least partially nest inside each other. This is clearly shown with reference to the two blades illustrated in figure 8B. In this way, in the direction of travel along the trunk, all the blades are in overlap with each other. This may help ensure that substantial if not complete circumferential enveloping of the blades occurs during pruning, ensuring that all limbs in the path of the pruning head are cut and removed from the trunk.

The blades 220 rely on a cutting action being applied to the limb 2. In some forms the blades only have one cutting edge to cause a cutting of the limbs from the trunk when the pruning head travels in one direction only along the trunk. In other forms it may cut in the one direction and in the opposite direction. Preferably each blade has a primary cutting edge 225. This is a sharp end for the blade. The primary cutting edge 225 is preferably the leading edge of the blade as the pruning head travels in one direction along the trunk. The edge 225 may lie in plane to which the axis 5, in use, is normal to. Alternatively, the edge may be undulating or serrated as an example. The blade so configured aligns with the direction of travel of the pruning head 200 and helps ensure that a blade deflection is minimal or eliminated to ensure a strong cut force is imparted on the limbs. The blade acts in compression when cutting. The compression direction is parallel the cutting direction.

The primary cutting edge 225 as seen in figure 11 is radially offset outwardly from the trunk contact surface 227 of the blade. This distance (A) may be a few millimetres. The offset helps prevent the blade from biting into the trunk itself. The cutting edge may have a lead-in surface 789 that is at a slight angle to the direction of travel up the trunk so as to help avoid the blade biting into the trunk. Much like the tips of a ski that help a skier travel over the surface of the snow. Offset may be achieved in other ways also (such as by skids, wheels or a ridge extending along the trunk contact surface of the blade) and not by a lead-in at the cutting edge. The distance A may be a desired and predetermined distance from the contact surface 227 to create a desired and length of a limb stub. This distance (A) may be 5mm for example.

The provision of a plurality (at least 4 and preferably 6) independently adjusting blades about the trunk circumference allows a consistent and hence close-to-the-trunk cut to be made of the limb. In some cases pairs of blades may have some dependent adjustment. Being independent, the radial position of one blade is not influenced by the radial position of another blade. For example one blade may be caused to ride over a knot of the trunk and as a result move radially outwardly. Were the blades interdependent, adjacent blades may then also move outwardly to a degree that may then not cut adjacent limbs in as close a proximity to the trunk as desired.

The primary cutting edge 225 will cut limbs from the trunk as the pruning head travels in one direction along the trunk. Optionally the blades 220 each have two cutting ends, provided by the primary cutting edge 225 and a secondary cutting edge 226. Preferably the primary cutting edge is upper more the secondary cutting edge. The primary cutting edge 225 impacts limbs or limb stubs 2 during movement of the pruning head in one direction, and the secondary cutting edge 226 may further cut the same limbs 2 a second time, during the movement of the pruning head 200 in the opposite direction. In use, the blade generally extends upwardly from the secondary cutting edge. The secondary cutting edge may be of the same or similar configuration at the primary cutting edge. The surface 227 preferably extends continuously between the cutting ends. The surface is preferably part cylindrical and of constant profile between the two cutting ends.

Optionally the primary cutting edge 225 has a cutting edge further away from the trunk 3 than the lower cutting edge 226. This allows the blade 220, in its second pass over the trunk to re-cut the stubs of a limb and this may be at more proximate distance to the trunk 3. As shown in Figure 11 the primary cutting edge 225 has a distance A from the trunk and the secondary cutting edge 226 has a distance B from the cutting edge to the trunk surface. The distance B may be 3mm.

In figures 12 and 13 there is shown the up-stroke and down-stroke of a cutter 220. In the up-stroke the cut length of the limb is a distance A from the trunk and on the down-strike the cutter 220 may trim the cut length of the limb to distance B which is less than distance A. The cut on the down stroke may be considered a shaving of the limb stub. This may require less force that a cutting through the limb on the upstroke. The blade, being subjected to less force during cutting, may therefore be subjected to less forces deforming or otherwise affecting the desired position or performance of the blade. The blade 220 may stay sharper for longer. This in turn should lead to a more accurate and/or consistent final cut length of the limbs of a tree. Such length may be around 3mm for example.

In some cases where each blade 220 can double cut, a consistent, regular, close and clean final cut of the limbs 2 may be achieved. The first cut may be considered a course cut of the limb and the second cut may be closer and more accurate cut. The blades are preferably composed of metal. The arrangement to cause the pruning heads 200 to move relative to the trunk to cut limbs from the trunk, will now be described. The arrangement is such that no or negligible vertical forces are applied to the tree bark and to the tree roots by the pruner. The action of cutting limbs from the trunk are, by virtue of the arrangement, all resolved between the upper and lower pruning head.

The pruner is configured to allow the upper pruning head and the lower pruning head to operate in concert to cut a branch or a plurality of branches in opposed directions. For example

1. When the upper pruning head and lower pruning head travel towards each other, the lower cutting edge of the upper pruning head and the upper cutting edge of the lower pruning head, cut limbs.

2. When the upper pruning head and lower pruning head travel away from each other, the lower cutting edge of the lower pruning head and the upper cutting edge of the upper pruning head, cut limbs.

In some embodiments the pruning heads may only cut limbs traveling towards or away from each other but in some embodiments the pruning heads may have two opposed cutting edges as herein before described and as such each pruning head may cut when traveling towards and away from each other.

The arrangement preferably comprises a traverser 1500 from which each of the upper and lower pruning heads depend. The traverser 1500 preferably comprises of a guide rail 1560. This guide rail 1560 is optionally able to suspend from the boom 12. Alternatively the traverser and/or guide rail is supported from the bottom, near the ground. The guide rail 1560 is rigid, straight and in use is parallel, or substantially parallel, the tree trunk. When the pruning heads 200 are being manoeuvred into proximity to the tree trunk, and before they engage the tree trunk, the guide rail preferably suspends substantially vertically. The guide rail is provided to support the upper and lower pruning heads and guide their movement long the tree trunk.

A simplified form of the traverser 1500 is shown in figures 4b and 4c. The lower pruning head 200A is connected and guided for movement by the guide rail 1560 using a traveller 210A. The upper pruning head 200B is connected and guided for movement by the guide rail 1560 using a traveller 21 OB. Each traveller may comprise of a carriage 1640 engaged to the guide rail 1560 in a sliding manner. The carriage may comprise of roller bearings or may instead be in a sliding relationship with the guide rail. The carriage is preferably captured to the guide rail in a manner so that movement of the traveller is predominantly confined to being along the rail in both directions.

In the preferred form both travellers 210A, 21 OB can co-dependently move along the guide rail 1560 in an unfettered manner. An end-stop 1622 may be provided by the guide rail to stop the travellers from dropping from the guide rail but other than that, both travellers may move along the guide rail in an unfettered manner other than being co-dependent on each other. Their co-dependence is established by a traversing mechanism 1588.

In a simplified form as seen in figured 4b and 4c, the traversing mechanism comprises of at least one actuator 1589 that is connected to the upper and lower pruning heads (e.g., via the upper and lower traveller). Optionally, connectors 1333 and 1334 connect the upper and lower travellers respectively to the actuator. In the example shown in figure 4c the actuator and connectors may have a rack and pinion configuration, but an optional form utilises two rams as will be described with reference to figures 15-18.

The actuator shown in figure 4c may comprise of a rotary motor such as a hydraulic motor that can rotate a pinion that is in a geared connection with the racks of or secured to the connectors 1333 and 1334. Upon rotation of the pinion in one direction the upper and lower pruning heads are caused to move (e.g., they are drawn) towards each other. Upon rotation of the pinion in the opposite direction the upper and lower pruning heads are caused to move (e.g., they are forced or urged) away from each other.

To illustrate this in use, reference is now made to figures 4d-g that show in sequence, a single pass of the pruning heads along a part of the tree trunk 3 to remove three limbs 2A, 2B, 2C from the trunk. In these figures parts of the invention are not shown for simplifying the explanation of operation.

In figure 4d, the upper and lower pruning heads are shown engaged to the tree trunk 3 in a start position. In the start position the upper and lower pruning heads are preferably distal most from each other. In an alternative configuration of operation, the pruning heads may have a start position that is proximal most to each other. The preferred start position however is that they are distal most each other, from which the pruning heads 200A, 200B are then drawn towards each other by the traversing mechanism for the first pass prune.

Once engaged to the tree trunk as shown in figure 4d, the actuator(s) may then initiate the traversing mechanism to draw the pruning heads towards each other. This may result in the upper pruning head 200B traveling down along the guide rail 1560 until the blade of the upper pruning head strikes a branch/limb 2C and stops moving down the guide rail. At this point the lower pruning head may start to travel upwardly along the guide rail 1560 until its blade strikes a branch/limb 2A. Continued actuation of the actuator will then cause the blades of the upper and lower pruning heads to initiate cutting into the respective limbs that they are engaged with. The lower limb 2A is likely to be larger and/or tougher to cut through than the upper limb 2C. This means that it is likely that the upper limb 2C will be severed first from the trunk, as seen in figure 4f. Once severed, the upper pruning head is free to move towards the next limb 2B. The blade of the lower pruning head may have cut partially through the lower limb 2A as seen in figure 4f. Once the blade of the upper pruning head 200B strikes the limb 2B a cutting action will initiate again and this time the lower limb 2A may be severed from the trunk allowing the lower pruning head to move upwardly along the guide rail 1560 to the limb 2B which may then be subjected to cutting from above and below by both the upper and lower pruning heads respectively in order for it to be severed from the trunk.

Once the first pass prune has occurred and the pruning heads are proximal most each other, one the following steps may occur:

(a) release of the pruning heads from the trunk may occur so that the pruning heads may be moved to the next tree, or

(b) return of the pruning heads to their distal most position may occur wherein the pruning heads perform a second pass prune of the trunk utilising the secondary cutting edges of the cutting blades as the pruning heads are forced away from each other followed by release of the pruning heads from the trunk so that the pruning heads may be moved to the next tree. The arrangement allows for a free vertically vertical sliding of the pruning heads relative to the guide rail in a way that transfers the force on the downward moving cutters on the upper pruning head, to the force required to be applied to the upward moving cutters on the lower pruning head.

The traversing mechanism also allows the upper pruning head cutters and the lower pruning head blades to meet but not touch. In this way all branch cutting pruning forces are balanced and apply no vertical force to tree bark or roots.

Optionally hydraulic rams are used as part of the traversing mechanism. This will now be described with reference to figures 15-18. In figure 15 the guide rail 1560 has the carriage 1640A for the lower pruning head 200A attached in a sliding manner. The guide rail also has the carriage 1640B for the upper pruning head 200B attached in a sliding manner. The traversing mechanism 1558 may comprise a base member 1587 that is preferably in a sliding connection with the guide rail 1560 so that it can slide relative the guide rail in a direction parallel the direction that the carriages can slide relative the guide rail. This direction is in use parallel the tree trunk.

Connected to the base member are two rams that each extend between the base member and a respective carriage. A first ram 1810 is connected at one end 181 1 to the base slide 1587 and at its other end 1812 is connected to the carriage 1640A. A second ram 1820 is connected at a first end 1821 to the base slide 1587 and at its other end (not shown) to the carriage 1640B. In the condition shown in figures 15 and 16 the rams are extended placing the upper and lower pruning heads distant from each other. In figures and 19 the rams have contracted to place the upper and lower pruning heads more proximal each other.

The rams may be powered by power supplied from the vehicle by the umbilical/cable. In some embodiments the power may be electrical power. In other embodiments the power is hydraulic power supplied by hydraulic fluid via a hydraulic pump and accumulator located in or at the vehicle 9. In the preferred embodiment the power is hydraulic power.

Other manners by which an opposed action of two pruning heads can be caused to move during pruning will also be envisaged by a person skilled in the art. For example the traversing beam may be telescopic to allow the pruning heads to move towards and away from each other in the opposed action as preferred.

In one form the pruner may have one of its pruning heads provided to not cut through limbs. In this form such a pruning head may merely be positioned or become positioned against a limb to provide a means for reaction of the actuator and the other pruning head. In such a form either the upper or lower pruning head may be designed to not cut limbs whereas the other of the upper and lower pruning heads will cut limbs. In such a form the non-cutting pruning head may not traverse along a length of the tree and it's the other (cutting) pruning head that does all or most of the traversing. For example the lower non-cutting pruning head may be placed just below a lower limb of the trunk and the upper cutting pruning head may be place above, with say 4 limbs intermediate of the upper and lower pruning heads. The upper and lower pruning heads may then be drawn together resulting in the lower pruning head abutting (if it is not already) against the lower limb where it will stay as the upper pruning head traverses downwardly towards the lower pruning head, progressively cutting each of the 4 limbs as it so traverses. It is envisaged that other traversing mechanism configuration could be employed including with the use of cables or other flexible elongate members used for drawing the upper and lower pruning heads together.

The opposed yet co-dependent action of the upper and lower pruning heads helps contain the cutting forces of the blades within the pruner with a reduced impact of axial direction forces being transferred to the trunk the tree. The impact of blades cutting branches, which may harm the young tree roots is also removed. All cutting forces are contained within the pruner, whereby upward moving cutters are connected via hydraulic rams to the downward cutters with a force of up to for example 70kN.

During the first prune of a tree, access to tree trunk is limited by branches. The vertically opposed pruning heads are able to be constructed as short in length and easily positioned under lowest branches and at an upper position 2-3m above ground level between branches. As can be seen in the figures the upper pruning head 200B is preferably identical to the lower pruning head 200A but are optionally presented in a 180 degree rotated configuration to each other.

Young trees ready for pruning, have particularly fragile and sensitive bark. The bark can be easily damaged and the result in many cases is the young tree dying. This is particularly the case with climbing pruners which utilise the young tree for traction to provide cutting force. Improvement is possible through modifications to transfer some, most or substantially all thrusting power to ground level so that the young tree trunk is used for guidance only with minimal contact force.

Figure 19 shows an alternative tree pruning apparatus or pruner 1. The vehicle 9 has operator cage 10 and a boom 12 supported from the vehicle 9, the boom allowing the operator to move or position the pruning head 200 and traverser 1500 (also referred to as a mast or column) attached to the distal end. Where possible the pruner may have features as described in the other examples. Multiple booms 12 may be used. The boom may have rotational, pivotal, and/or telescopic movements to allow the operator to position the end of the boom appropriately. Hydraulic actuators, or other actuators, may be used to control the movements of the boom and/or vehicle. A hydraulic accumulator 11 provides power to the hydraulic systems. Alternative structures capable of positioning the traverser, stem or mast 1500 and pruning head 200 at or near the trunk of a tree can also be used. In some cases automatic alignment of the mast and a tree is achieved through verticality sensors and/or position sensors and/or other sensors.

The traverser or mast 1500 has a foot or foot portion 1510 at or near a first end configured to contact the ground or surface near the base of the tree. The foot 1510 provides stability to the traverser 1500 and/or pruning head 200. This is particularly useful during operation because forces can be transmitted to the ground 6 rather than to the tree 4. The foot 1510 may be attached to the boom by a connector 1515 or connection apparatus. Figure 19 shows this connection 1515 at the base of the traverser 1500 so as the operator can easily position the foot 1510 on the ground near the trunk of the tree. Connection to the bottom of the traverser near the ground reduces the number of branches that may reduce visibility, as well as reducing the componentry at the top of the mast or traverser 1500. Alternatively the boom 12 may be connected at or near the top or distal end of the traverser 1500 at or near cap or top 1514. However, this adds additional machinery at the top of the traverser 1500 which must be manoeuvred into position amongst the branches before cutting which is undesirable. The connector 1515 may have actuators to enable the foot 1510 to be rotated and/or positioned on the ground so that the traverser 1500 is parallel to the tree trunk (the tree trunks typically being vertical).

Figure 20a shows a perspective view of an example pruner showing the end of the boom 12, the connector 1515 and the traverser 1500. Figure 20b shows detail of the connector and traverser 1500 near the foot 1510. The traverser 1500 has a bracket or arm 1530 attached on each side of the foot area (alternatively a single or a plurality of brackets or arms may be used). The bracket 1530 is attached to the connector 1515 by connections 1531 , 1535 which may be bolts. A series of actuators may be used, such as hydraulic ram 1532 configured to change the tilt, or actuator (or twist connection) 1533 configured to rotate the bracket and traverser around the longitudinal axis of bolt or connector 1534. The coupling 1536 to the boom 12 is configured to hold the connector 1515 steady and allow the operator to accurately position the pruner at the base of a tree. Changes to the connector 1515 may be made as known in the art so allow or adjust the manoeuvrability of the traverser or mast 1500.

Figure 21 a shows a perspective view of the foot 1510 and traverser portion 1500, a side view of the same is shown in Figure 21 b. The foot 1510 is shown as a planar plate 1519 extending orthogonally to the longitudinal axis of the traverser 1500 so as to provide a plane that is substantially horizontal or parallel to the ground. Other geometries for the foot 1510 are possible. For example the plate 1519 may be shaped or curved so as to provide a range of possible angular positions in which it rests upon the ground. The plate 1519 is not required, instead the foot 1510 may be one or more ribs or brackets - for instance arranged vertically, or the base of the traverser 1500 may sit directly on the ground. For example, the brackets 1530 could extend below the mast 1500 to provide a suitable foot. Suitable foot structures will provide support to the traverser against the ground, particularly when the pruning forces are applied. Bracket 1530 is shown extending away from the traverser 1500 and foot 1510. This bracket is configured to attach to, or form part of the foot connector 1515. Optionally it has a flat or level upper edge 1532 and/or an angled tapering lower edge 1531. Similarly the bracket may taper as it extends from the foot 1510. The tapering lower edge allows the operator more manoeuvrability to position the foot under the tree as obstacles can be avoided, it also reduces the size and weight of the bracket 1530. Alternative bracket shapes may be used. Vertical plate or connection plate 1543 (see Figure 21 b) is optionally provided between the bracket 1530 and traverser 1500 to provide a secure contact and/or connection surface.

Traverser 1500 extends away from the foot portion 1510. In use it will extend in a substantially vertical direction so as to match the position/direction of a tree trunk. This is typically at 90 degrees to the plane of foot plate 1519, which is optionally placed directly beneath the traverser 1500 at a first end. The distal end of the traverser 1500 may have a cap or shield 1514 configured to protect the top of the traverser 1500 from damage or allow the traverser to be safely pushed into tree branches when positioned at a trunk to be delimbed. In some cases the cap or shield 1514 may be shaped (e.g., pointed or rounded) to improve position ability of the mast between branches. The traverser 1500 may be any suitable length - for example 4 meters to allow a first prune of pine trees. Optionally its width is kept to a minimum given the required strength to improve an operator's visibility of the tree. The traverser 1500 may be a beam, for instance an I-beam as shown or T-beam, (although other shapes such as triangular, square or rectangular box cross-sections may also be used). The traverser 1500 may be unitary or have a plurality of connected parts to form the required shape. The guide rail 1560 may be formed by the front face of the beam. As with the previous example the guide rail 1560 is rigid and straight to support the pruning head(s) 200 and guide their movement along the tree trunk, in use. Optionally the movement of the pruning head begins at or near the foot end of the traverser 1500 and travels to the distal or cap end. The traverser may be substantially rigid so as to support the pruning head and control the forces during pruning, however a level of play or movement or flexibility allows the traverser to adjust for movement or bumps to the pruning head 200. The traverser 1500 has an actuator 1540 configured to move the pruning head 200 along the guide rail 1560. Optionally the actuator 1540 is arranged at or near the base of the traverser 1500 or foot 1510 so as to reduce the weight and machinery at the top of the traverser 1500. Alternatively the actuator 1540 may be remote and connected to the traverser. However, having the actuator at the base of the traverser 1500 improves the transfer of the forces to the ground (instead of the tree) due to the additional mass. Figure 21a shows an embodiment where the actuator 1540 is connected to a drive wheel or cog 1555 which is connected to a pulley or chain drive 1572. The pulley or chain drive 1572 forms a loop running along the length of the traverser 1500 so as to allow the actuator 1540 to drive the pruning head 200 (when connected to the pully, chain or chain drive 1572) along the length of the traverser 1500. The cog or toothed wheel 1555 is driven by an actuator, such as hydraulic motor 1540 shown arranged at the foot 1510 of the traverser 1500. Other actuating systems, types of endless members 1572, or drive cogs or systems, may be used as appropriate to provide movement of the pruning head 200, for instance rack and pinion or ram configurations related to those described above.

Figure 21 c provides a detailed view of the attachment of the pruning head 200 to the traverser 1500 and guide rail 1560. The pruning head 200 is connected to guide rail 1560 by a traveller 210A or carriage. In the illustrated example the traveller 210A is secured to guide rail 1560 by frame members which lock behind the front face of the guide rail, with a connection to the actuator cable, looped member, or drive system 1572. This allows the traveller 210A to move along the length of the traverser 1500. In other cases different connections between traveller 210A and guide rail 1560 or traverser 1500 may be used. For example, there may be a direct connection between the actuator 1540 and the pruning head 200 or traveller 210A, or the pruning head 200 may be secured to the outside of the guide rail 1560 instead of the brackets extending behind the guide rail 1560. In a further alternative the carriage arrangement of the previous example could be used.

Figure 22a shows a horizontal cutaway view showing the connection between the guide rail 1560 and the pruning head 200. Figure 22b shows a vertical cutaway of the same section. The pruning head 200 is attached to traveller 210A which is connected to, or around, guide rail 1560 of the traverser or mast 1500 so as to be slidably moveable up and down the guide rail 1560. In the illustrated embodiment the traveller or carriage is formed by first members 1562, second member 1563, and a spacer 1561 arranged between the first and second members 1562, 1563. The second member 1563 provides a support or attachment surface for the pruning head 200 while each of the first members 1562 (although a single first member may be used) extends around the back of guide rail 1560 to prevent the traveller 210A from moving off the rail. A gap between the first members 1562 allows the traveller 210A to move along the central beam 1501 of the traverser, while ensuring the traveller remains on the traverser 1500.

The first and second members 1562, 1563 may be bolted or otherwise connected around the guide rail 1560 of the traverser. For example the first and second members 1562, 1563 may be bolted or welded together at each side of the traverser 210A. A recess 1564 formed within the first and second members 1562, 1563 allows the traveller to pass along the guide rail 1560 (i.e., the front surface of the traverser, or the front of the I-beam) while being held in position on the guide rail. Spacer 1561 can control the amount of play or horizontal movement of the traveller relative to the guide rail 1560. The surface of spacer 1561 which contacts the guide rail may be smooth or configured to run smoothly up the guider ail 1560. Spacer 1561 may be formed by a high density plastic component configured to reduce friction, such as ultrahigh density polyethylene. Other spacers, including those configured to reduce friction or improve movement of the traveller 210 up the guide rail may be used, for instance ball bearings or mechanical techniques). At least one, and preferably at least two connections are made between the traveller and the chain drive 1562 running up and around the traverser 1500 so as to enable movement of traveller 210 by actuator 1540.

Figure 22a also shows brackets or arms 1530 connected, through plate 1543, to the traverser 1500. The brackets or arms provide a connection from the traverser 1500 to the boom 12 of the vehicle 9. Figure 22a shows that gears or actuation connections 1555 may be present on both sides of the central beam 1501 of traverser 1500. Although not required, this helps balance any horizontal forces on each side of the traverser 1500. It also reduces the size of the traverser 1500, because two smaller chain drives can be used (one on each side of central beam 1501 , or on each side of traverser 1500. This avoids a single larger chain drive being required on one side, reducing the visibility of an operator. In alternative cases the traverser may have a different shape (instead of an I- beam) and therefore use different connection techniques. For example the traverser could be a square beam, with the pruning head attached to and moving up an outer surface. A further alternative is a T-beam with the guide rail 1560 being the front face. Other techniques for connecting the traveller 210A may also be used, provided they allow the traveller 210A the ability to slide up and down the mast or traverser 1500 (or another suitable surface or beam able to be brought parallel the tree trunk). The traveller should be able to withstand the large forces used to propel the pruning head upwards, these may be more than 40000N. Although the pruning head 200 is shown at the foot of the traverser it is understood that the starting position may be slightly higher, as appropriate to prune the lowest branches, for instance within 0.5 or 1 meter of the foot.

Figure 23a shows an example of a pruning head 200 for the pruning machine. The pruning head 200 is shown attached to traveller 210A. In practice, the pruning head 200 and traveller 210A may be unitary or connectable components. Figure 23a shows brackets, frame or plates 230A, 230B connecting arms 660 which support blades 220. The brackets or plates 230A, 230B act similarly to the chassis 610 or base chassis 201 of the previous examples to support the arm and blade in the desired position. As shown the traveller 210A may support a bracket, one set of brackets, or a plurality of brackets such as the two shown in Figure 23a. For added support and strength two plates 230B may be used, optionally arranged in parallel on opposite sides of the arms 660.

Figure 23b shows a front view of the pruning head 200 with two pairs of blades 220 arranged on the traveller 210A through brackets or chassis 660. Two blades 220 are attached to each set of brackets 230A, 230B. A linkage 235 between the arms 660 of each pair of arms 660 ensures that the closing of the blades 220 is even or equal. This helps to ensure good coverage of the trunk circumference. This may be driven by actuator 661 connected to the bracket 230B. Optionally a level of play in the system, both in the closing mechanism of arms 660 and/or the traverser allows some movement of a first arm without substantial movement of the second arm, this allows a blade 220 to move around a bump without opening the arms from the tree. The pairs of blades are offset from one another so as to provide a different angle relative to a trunk in the mouth of the pruner. This is achieved in Figure 23b by the attachments of the brackets 230A, 230b to the traveller 210A being horizontally offset so as the pivot point of the arms 660 is different for each pair of blades. Furthermore the brackets 230A, 230B are mirror images of one another so that the mouths of the set of blades 220 (or arms) open in different directions (other variations may use arms 660 at different angles but not mirror images). By making these directions overlap the offset and opening direction can be engineered to securely surround a trunk 3 in the pruning head 200 and ensure that the blades 220 provide full coverage around the circumference of the tree. This ensures all branches are pruned cleanly, and preferably by the middle of a blade 220. Advantageously this coverage focusses on the centre of the blades 220 which form best cutting edge. Figure 23b clearly shows the use of two planar pieces to make brackets 230A, 230B with a set of linkages on each planar piece, so that there are two linkages for each pair of blades. The actuator 661 may be placed between the two plates for improved safety and protection.

Figure 23c shows a plan view of the pruning head 200. The plan view shows how the mouths of the pairs of arms or jaws 660 are directed in different, overlapping directions. That is to say the direction of the axes between each set of arms or jaws 660 crosses (see also axis 677 in Figure 24b). In some cases there may be a single pair of arms 660, or more than two pairs. In some cases an additional blade 220 is arranged above the uppermost bracket 230 or chassis to protect the chassis from impacts of branches. Figure 23c also shows a top view of the traveller 210A showing first plates 1562 and second plate 1563 creating a recess to fit around the guide rail 1560. The jaws or arms 660 may be operated as relatively low pressure to allow closing without applying unnecessary force to the tree trunk.

Figures 24a and 24b show a single set of arms orjaws 660 isolated from the traveller 210 and with the upper bracket 230B removed. This allows a view of the actuator 661 used to actuator the jaws 660. The actuator may extend between a first point such as bolt 662 secured to the bracket 230B and a second point or bolt secured to one of the jaws 660 so that extension of the actuator causes the jaws 660 to close. Fixed pivots 669 at the ends of jaws 660 mean that the actuation causes rotation of the jaws. Other closing arrangements are possible where they allow the jaws to close around a tree trunk placed in the pruning assembly 200. The plan view of Figure 24b shows how a first end of the arms 660 is toothed, or otherwise connected, to the second arm 660 so as to move dependent on one another. This allows a single actuator 661 to move both arms 600 and forces the arms to close evenly. The toothed connection 235 is between the pivots 663 so as provide strength. As discussed, the teeth may have a controlled amount of play to allow the blades to move over bumps without pushing the second jaw away. This may be set in conjunction with the soft hydraulic closing force of actuator 661 . Figure 24b illustrates the angle of the jaws shown by axis 231, where two or more jaws are used this axes should intersect so as the jaws shut about a trunk at different directions. Optionally the directions and axes are arranged so that the blade points 301 or centres are substantially evenly spaced around the trunk.

Figure 25a shows a perspective view of blade 220 and roller 1505 disconnected or isolated from arm or jaw 660. The design of these blades improves the pruning capability of the system. The blade 220 has a blade face 227 (the trunk contact surface used in previous examples, but optionally configured to sit away from the trunk, in use) configured to sit near or encircle the trunk of the tree as the blade moves up the tree. In these examples the trunk contact surfaces refers to the portion or face of the blade that follow the surface of the trunk. In many cases the face of the blade, which may be referred to as the trunk contact surface, will not contact the trunk, being spaced away by a spacing means such as guide wheel 1505, to reduce bark damage. Alternatively the trunk contact surface 227 may be referred to as a trunk facing surface, the face of the blade, the inner surface of the blade. In alternative examples the pruning mechanism described in this example can be combined with the pruning head described previously -i.e., one where the face of the blade contacts the tree trunk.

Optionally the trunk contact surface 227 or face of the blade 220 can be viewed as a number of portions, with a central arcuate or curved portion 303 being concave to follow the circumference of a trunk and wing portions 304 on the side of the central portion 303. The wing portions are optionally arcuate or curved, optionally being convex or bending away from the tree. This shape improves the removal of branches from the blade and ensures some variability in tree diameter is allowable (nominal tree diameter for pruning is 170mm, but the system may be set up for different diameters as required).

As discussed, the blade edge 225 may have features to improve cutting. In the illustrated embodiment the cutting edge 225 is pointed or comes to a tip 301 such that the centre of the blade 220 is longer (or taller) than the edges of the blade. Optionally the slope of the cutting edge 225 from the tip 301 to the edges, or at least to the wing portions 304 is approximately 45 degrees, or around 55 degrees. However it may be in a range between 30 and 70 degrees, between 40 and 60 degrees, 40 and 50 degrees, 45 and 55 degrees or 50 and 60 degrees. Testing has shown that this angled slope and pointed blade improves the cutting performance of the blade 220 over chisel type designs.

The cutting surface 225 may have a second slope across the width of the cutting surface (so between the face 227 of the blade and the back surface of blade 220). In some cases this slope is around 45 degrees. However it may be in a range between 20 and 80 degrees, 30 and 70 degrees, between 40 and 60 degrees, 40 and 50 degrees, 45 and 55 degrees or 50 and 60 degrees. In other cases it is flat (i.e., 90 degrees), or perpendicular to the blade face 227. This differs from the blade examples in Figure 12, which used the blade width to set the cutting point. Instead the rollers 1505 set the distance of the blade and the blade tip is arranged on the face of the blade. However either system may be used.

The cutting edge 225 may be serrated or rough to improve cutting or pruning. It has been found that small serrations improve the cutting performance of the blade 220. Advantageously serrations, teeth or roughness less than 10mm, less than 5mm or less than 1 mm have been found to improve performance. In some cases serrations or saw teeth that are too large do not work, because the serrations or saw teeth are broken or bent by the impact into branches. The serrations may have a width much longer than their height, so while the height of the serrations may be less than 10mm, 5mm, 1 mm as described the width for any of these may be greater than 20mm, 10mm or 5mm. This may be seen as a small angle extending for a larger distance away from the blade then a greater angle extending for a short distance returning to the blade, so as to make a series of low serrations. The front of the serrations may face away from the point 301 of the blade 220 with a large rake angle of greater than 60, 70 or 80 degrees. This difference in angle on each side of the serration (i.e., with a low angle down provides a useful serration for pruning.

Figure 25b is a plan view of a single blade 220 detached from arm 660. This shows the position of roller 1505 relative to the blade 220. The roller 1505 acts to control the distance between the blade 220 and the trunk. This allows the blade 220, and particular cutting surface 225 to be maintained at the best distance to prune the limbs from the trunk. It is noted that the surface of roller 1505 is close than the blade face or to reduce unnecessary contact with the trunk. The distance to the blade is typically around 6mm but may vary depending on the closeness of pruning required. The roller 1505 is attached to blade 220 by brackets through which axle 1506 passes, the axle allows the roller to turn as the pruning head moves up the trunk. The roller 1505 optionally has a variable diameter to improve performance. The diameter of the roller 1505 is smaller in the middle of the roller 1505, below the point of the blade 301 . This follows the curve of the blade 220 so as to maintain the appropriate pruning distance. The curve in the roller 1505 also provides greater tolerance to bumps or roughness on the trunk compared to a single flat wheel because it spreads the area in contact with the trunk so moves with bumps across the width of the roller 1505. The rollers are optionally made of rubber or other resiliently deformable material. It may be relatively soft or otherwise configured to protect the trunk surface when rolling over it. The curve of the roller may follow the expected diameter of the trunk to be pruned. The surface of the roller may be configured to limit trunk damage. A soft closing force may be used to bring the tollers into contact with the trunk so ad to allow them to guide the blade without damaging the tree and/or bark.

Figure 25c is a front view of the blade 220 showing the width of roller 1505 relative to blade 220. Optionally the roller 1505 is wide enough to cover the main cutting edge of the blade 225, this means extending across between 40-70% of the blade, preferably around 50% the width of the blade. This means the roller is picking up protrusions or bumps in the trunk of the tree across the cutting edge of the blade, reducing damage to the bark. The roller 1505 is optionally located in an opening 307 in the blade 220 or face of the blade 227. Alternatively, the roller 1505 could be in a recess in the base of the blade face or surface 227. Having the roller 1505 in the opening 307 enables the roller 1505 to be positioned as close to the top of the blade, or cutting edge 225, as possible. The opening 307 allows added strength to the blade by providing a greater surface area of the blade face due to the portion of the blade 205 below the opening. The height of this portion underlying the roller opening 307 may be configured to bring the necessary strength to the blade. The spacer of the roller relative to the cutting edge of the blade 220 controls the closeness of the prune. As discussed above an alternative is to use the blade face itself to control the distance of the cutting edge.

Figure 25d is a side profile of the blade 220 which shows the curve or arc of the blade face 227 as well as the slope or angle of the cutting surface 224. The angle is shown as about 45 degrees sloping away from the face (inside) of the blade. A 90 degree (horizontal in Figure 25d) angle, or an angle between 45 and 90 degrees, or less than 45 degrees is also possible. The opening 307 is located in the middle of the blade 220. The example has a section 305 of the blade face 227 below the opening 307 of about half the width of the opening. This width may be adjusted to control the strength of the blade 220.

In use the operator places the pruner mast 1500 in close proximity to the tree aligning the mast with tree trunk. The pruner base or foot 1510 is placed on ground level to transfer cutting forces thereto. The jaws 660 then softly close, such that rollers contact the tree and maintain approximately a 6 millimetre gap between blade cutting edge and trunk. After closing the jaws, the two pairs of blades are propelled vertically by the chain drive to the top of the mast unit. Optionally the rollers are the only contact with the trunk, and the majority or substantially all the forces are reflected to the foot and/or ground). The blades cut though any branches extending from the trunk. The pruning head 200 and blades 220 are then be returned to ground level for the next tree. The mast may be typically 4 metres in length on the first prune unit. This will provide clear wood from ground level to a height of four metres.

Figure 26 shows a further example of a pruner. This pruner is similar to the previous example but has been configured to perform subsequent second and/or third prunings. In this case vehicle 9 is similar to the earlier example. However the traverser 1550 has been modified to extend or telescope. Two or three years after the first pruning the tree has continued to grow and branches have now appeared or grown at a height greater than the height of the traverser. For example the first pruning may be to a height of 4 meters. The second pruning may be for tree heights of 4 to 8 meters. A third pruning may cover heights from 8 to 12 meters. Because of the growth of the tree these higher sections are now the appropriate diameter for pruning (nominally 170mm). The previous example of a pruner is configured for only the first prune, as the pruning head moves from the ground to the top of the traverser. However, this lower portion is wider than the 170mm diameter for pruning.

The pruner of Figure 26 has a pruning head 200 at or towards the top of a first or moving portion 151 1 of traverser 1550. The first portion is slidably connected to a second or base portion 1512 of the traverser so as it can be driven upwards. This extension or telescoping allows the pruning head 200 to move the distance of the extension portion - for example from 4 meters to 8 meters. Optionally a support head 240 is located at or near the bottom end of the extension portion 151 1 to support the location of the traverser 1550. Optionally the support head 240 does not have cutting blades attached (because the trunk will have already been delimbed by the pruning head 200), although blades, or trunk contacting surfaces may be used. Rollers or other guide devices may be used. Advantageously, this pruner has no parts (or at least few parts) which extend above the pruning head 200, so that the traverser 1550 can easily be placed near the tree without having to fight or push through the limbs or branches before they are pruned. This makes the pruner much easier to use than previous devices where the boom connects to the top of the traverser 1550, or where a bulk of machinery is required at the top of the traverser 1550.

Figure 27 shows the isolated traverser 1550 with extended 151 1 and base portions 1512. A similar driving means may be used to telescope the traverser as was used in the prior examples. For example an actuator may drive, through toothed cog or gear 1517 a drive chain 1518 (or cable or endless member) extending up the base portion 1512 and acting to push the extension portion. This may be achieved by a connection between the base of the extension portion 151 1 and part of the drive chain 1518. This actuation system may be the same as used in the first prune embodiment, but with the pruning head and/or traveller replaced by extension portion 151 1 and running around the outside of the base portion. The described actuator/traverser designs can be applied to this version. Figure 27 shows the full extension, so after the tree 5 has been delimbed. As in the previous example, foot 1510 including foot plate 1519 provides a solid resting place for the traverser and ensures all forces are transferred safely to the ground 6 instead of tree 4.

Figure 28 shows a detailed view of the pruning head 200 and support head 240 on the extension portion 1511 viewed from below the foot 1510 or foot plate 1519. In this example the extension portion is formed by an outer surface extending around the inner portion of the base 1510. This means that in the non-extended position the base portion 1512 is covered by the extension portion. This arrangement allows the pruning head 200 and support head 240 to be attached directly to extension portion 151 1 by brackets 230A, 230B, 230C. Alternatively travellers, as discussed above, may be attached to the extension portion 151 1. The base 1512 and extension portions 151 1 may be constructed in other ways, provided the extension portion is able to move vertically to carry the pruning head 240 up the trunk of a tree.

Figure 29a shows the pruning head in the closed position, that is to say in the position in which it is closed around a trunk during the delimbing process. The pruning heads 200 is similar to that previously described, although other pruning heads are possible. Figure 29a provides a detailed view of the pruning head 240 at the top of the extension portion 200 secured around a trunk 4. The closed jaws 660 mean that the blades 220 make contact at the distal end 229 of wing portions from the brackets 230A. The relative position of the upper and lower blades in the closed position can be seen as providing the blade points at about 90 degrees from each other. In other versions further blads may be used to improve coverage. For example 3 or 4 sets of jaws could be used.

Figure 29b shows a plan view of the closed jaws 660 showing the opening formed around the trunk in the closed position. The offset and mirrored nature of the jaws has been found to improve coverage compared to the three bladed examples where two arms are connected to a back blade. Figure 29c is a detailed view from below with the trunk removed which shows the different axis around which the jaws 660 close to bring the blades together. In some cases the distal ends 229 of the blades may not touch, depending on the exact dimensions of the tree. The aperture of the closed blades is seen, for example in Figure 29b to be non-circular, although circular versions may also be designed. The non-circular or ovular opening is advantageous to improve flexibility or adaptability of the pruner to trunk variations. Axis 231 is shown through the closed arms or jaws 660, which cross a similar axis (not marked) of the bottom arms or jaws). Centre points of the blades are spaced around the circumference of the opening for the trunk, with good coverage at the meeting points 229 of the blades 220.

In use the operator places the pruner mast 1500 in close proximity to the tree aligning the mast with tree trunk. The mast base or foot 1510 is placed on ground level to transfer cutting forces thereto. The pruning head is located at the top of the base portion or moved up to the point at which the diameter is less than 170mm (or the relevant pruning diameter). The jaws then softly close, such that rollers maintain approximately a 6 millimetre gap between blade cutting edge and trunk. After closing the jaws, the extension portion is propelled vertically by the chain drive, causing the pruning head to extend up the trunk. The pruning head may then be returned to its initial position by retraction of the extension portion, ready for the next tree. The mast may be typically 4 metres in length on the first prune unit. This will provide clear wood from ground level to a height of four metres.

Where in the foregoing description reference has been made to elements or integers having known equivalents, then such equivalents are included as if they were individually set forth.

Although the invention has been described by way of example and with reference to particular embodiments, it is to be understood that modifications and/or improvements may be made without departing from the scope or spirit of the invention.

For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence.

Claims

1. A tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a traverser comprising a foot configured to sit on the ground near the trunk and a distal end extending vertically substantially parallel to the trunk, the traverser having a first portion connected the foot, and a second portion slidably connected to the first portion, ii. a first pruning head mounted to second portion of the traverser and configured to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk so that when said first pruning head traverses up the trunk the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk wherein the second portion is configured to extend upwards relative to the first portion, to traverse the first pruning head up the tree, pruning the tree.

2. A tree pruning apparatus as claimed in claim 1 wherein the second portion surrounds, or fits over, the first portion.

3. A tree pruning apparatus as claimed in claims 1 or 2 wherein the first pruning head is mounted at or near the top of the second portion.

4. A tree pruning apparatus as claimed in claims 1 to 3 further comprising a support head configured to capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first support head supporting the traverser aligning to the trunk.

5. A tree pruning apparatus as claimed in claims 1 to 4 comprising an actuator for extending the second portion, the actuator located at or near the foot.

6. A tree pruning apparatus as claimed in claims 1 to 5 wherein the second portion is about 4 meters long.

7. A tree pruning apparatus as claimed in claims 1 to 6 wherein the first pruning head is mounted to the outside surface of the traverser. 8. A tree pruning apparatus as claimed in claims 1 to 7 wherein the traverser extends to substantially twice its non-extended height.

9. A tree pruning apparatus as claimed in claim 1 to 8 wherein the traverser is configured to attach to a boom at or near the foot of the traverser.

10. A tree pruning apparatus as claimed in claims 1 to 9 wherein the traverser comprises a chain drive, the second portion mounted to the chain drive such that movement of the chain drive extends the traverser.

11. A tree pruning apparatus as claimed in claims 1 to 10 wherein the foot comprises a base plate, optionally wherein the base plate is planar.

12. A tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a traverser comprising a foot configured to sit on the ground near the trunk and a distal end extending vertically substantially parallel to the trunk, ii. a first pruning head slidably mounted to the traverser and configured to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk so that when said first pruning head traverses up the trunk the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk.

13. A tree pruning apparatus as claimed in claim 12 wherein the traverser is configured to attach to a boom at or near the foot of the traverser.

14. A tree pruning apparatus as claimed in claim 12 or claim 13 wherein the first pruning head is configured to move from a position at or near the foot of the traverser, to a position at or near the distal end of the traverser.

15. A tree pruning apparatus as claimed in claims 12 to 14 wherein the first pruning head is mounted to a traveller, the traveller slidably mounted to the traverser. A tree pruning apparatus as claimed in claims 12 to 15 wherein the traverser comprises a shield configured to protect the upper end of the traverser. A tree pruning apparatus as claimed in claims 12 to 16 wherein the traverser comprises a chain drive, the traveller mounted to the chain drive such that movement of the chain drive moves the traveller along the traverser. A tree pruning apparatus as claimed in claim 17 wherein the chain drive is driven by an actuator to move the traveller. A tree pruning apparatus as claimed in claims 12 to 18 wherein the foot comprises a base plate, optionally wherein the base plate is planar. A tree pruning apparatus as claimed in claims 12 to 19 wherein the foot is rotatably connected to the boom and configured to rotate to allow alignment of the traverser and the trunk. A tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a first pruning head able to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising a first and second pairs of jaws, each jaw comprising a blade to locate about and in close proximity to the trunk so that when said first pruning head is captured to the trunk and traverses the first length of the trunk, the blades can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk, wherein the first and second pairs of jaws are offset and angled toward one another so as to surround the trunk when in a closed position. A tree pruning apparatus as claimed in claim 21 wherein the blades are arcuate or curved so as to follow the curve of the tree. A tree pruning apparatus as claimed in claim 21 or 22 wherein, for each pair of jaws, the jaws are linked or joined such that movement of a first jaw will move the second jaw. 24. A tree pruning apparatus as claimed in claim 23 wherein the jaws are connected so that rotation of a first jaw urges rotation of a second jaw.

25. A tree pruning apparatus as claimed in claim 24 wherein the first and second jaw have teeth that engage one another.

26. A tree pruning apparatus as claimed in claims 21 to 26 wherein the jaws are supported by a frame attached to the traveller.

27. A blade for a tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said blade comprising:

An arcuate surface configured to face the trunk; and

28. A blade as claimed in claim 27 wherein the point is centred on the arcuate surface.

29. A blade as claimed in claim 27 or 28 wherein the cutting edge slopes away from the point at an angle of between 20 and 80 degrees, between 30 and 70 degrees, between 40 and 60 degrees, between 50 and 60 degrees, or substantially 55 degrees.

30. A blade as claimed in claims 27 to 29 wherein the arcuate surface has first surface with a concave curve and wing surfaces with convex curves.

31. A blade as claimed in claims 27 to 30 wherein the arcuate surface has first surface with a concave curve and wing surfaces with convex curves.

32. A blade as claimed in claims 27 to 31 wherein the cutting edge is angled at substantially 45 degrees.

33. A blade as claimed in claims 27 to 32 comprising a position guide configured to space the blade away from the trunk in use.

34. A blade as claimed in claim 33 comprising an opening in the arcuate surface, wherein the position guide is configured to pass through the opening.

35. A blade as claimed in claim 33 or 34 wherein the position guide is a roller configured to contact the trunk of the tree in use. A blade as claimed in claim 35 wherein the roller has a variable diameter along the width of the blade, optionally wherein the diameter reduces around a midpoint of the roller. A blade as claimed in claims 35 or 36 wherein the roller extends across at least

40, at least 50, at least 60 or at least 70 percent of the width of the blade. A blade as claimed in claims 35 to 37 wherein the roller is connected to a frame supported by the blade. A blade as claimed in claims 27 to 38 wherein the cutting edge of the blade is serrated. A blade as claimed in claim 39 wherein the serrations are any one of: less than 10mm, less than 5mm, or less than 1 mm high. A blade as claimed in claim 40 wherein the serrations are any one of: greater than 20mm, than 10mm, or greater than 5mm long. A pruning head comprising a pair of arms, each arm connected to a blade as claimed in claims 27 to 41, the arms configured to move between an open position in which the blades are open to allow the blades to surround a trunk, and a closed position in which the blades closely surround the trunk. A tree pruning apparatus as claimed in any one of claims 1 to 26 comprising at least one blade as claimed in claims 27 to 41. A tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a first pruning head able to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk so that when said first pruning head traverses up the trunk the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk, and ii. a second pruning head able to (a) capture to the trunk above or below the first pruning head and be caused to traverse along a second length of the trunk and (b) be released from the trunk, said second pruning head comprising at least one blade to locate about and in close proximity to the trunk when said second pruning head is captured to the trunk, so that when said second pruning head traverses down the trunk the blade can cut through any limbs on the second length, to sever them from the trunk in close proximity to the trunk. A tree pruning apparatus as claimed in claim 44 wherein the first and second pruning heads are able to be caused to traverse along respective lengths of the trunk in a co-dependent manner. A tree pruning apparatus as claimed in claim 44 or claim 45 wherein a traversing mechanism is operatively connected to both said first and second pruning heads to (a) draw the first and second running heads together and/or (b) push the first and second pruning heads apart along their respective lengths. A tree pruning apparatus as claimed in claim 46 wherein the traversing mechanism resolves the force experienced by said first pruning head from its blade during cutting of a limb to an equal and opposite force applied by the blade of the second pruning head to cut the or another said limb of the trunk. A tree pruning apparatus as claimed in claim 46 wherein the traversing mechanism resolves the force experienced by said first pruning head from its blade during cutting of a limb to an equal and opposite force applied by the blade of the second pruning head to cut another said limb of the trunk. A tree pruning apparatus for at least partially pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said apparatus comprising: i. a first pruning head able to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk so that when said first pruning head is captured to the trunk and traverses the first length of the trunk, the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk, and ii. a second pruning head able to (a) capture to the trunk at a location spaced from the first pruning head and (b) be released from the trunk, iii. a traversing mechanism to push and/or pull the first and second pruning heads co-dependently away and/or towards each other in a manner so that said first pruning head acts, in traversing said first length, cuts through any limbs on the first length, in reaction from said second pruning head being located against another of said limbs. A tree pruner as claimed in claim 49 wherein the first pruning head is able to (a) capture to the trunk and be caused to traverse along a first length of the trunk and (b) be released from the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk so that when said first pruning head traverses up the trunk the blade can cut through limbs on the first length to sever them from the trunk in close proximity to the trunk. A tree pruner as claimed in claim 49 or 50 wherein the second pruning head has no blade and hence does not cut through limbs. A tree pruner as claimed in claim 49 wherein the second pruning head is able to (a) capture to the trunk above or below the first pruning head and be caused to traverse along a second length of the trunk and (b) be released from the trunk, said second pruning head comprising at least one blade to locate about and in close proximity to the trunk when said second pruning head is captured to the trunk, so that when said second pruning head traverses down the trunk the blade can cut through any limbs on the second length, to sever them from the trunk in close proximity to the trunk. A method of pruning a tree that presents a plurality of tree limbs projecting at various heights from the tree trunk of the tree, the method comprising: i. engaging a first pruning head and a second pruning head to and about the trunk at spaced apart locations to position at least two limbs intermediate of said first and second pruning head, the first pruning head comprising at least one cutting blade presented for use to cut through tree limbs, ii. co-dependently drawing said first and second pruning heads towards each other to cause said at least one cutting blade to shear through a tree limb to sever it from the trunk. A method as claimed in claim 53 wherein said first and second pruning heads are co-dependently drawn towards each other to cause said at least one cutting blade of said first pruning head to shear through successive tree limbs to sever them from the trunk. A method as claimed in claim 53 or 54 wherein the second pruning head comprises at least one cutting blade presented for use to cut through tree limbs. A method as claimed in claim 55 wherein said first and second pruning heads are co-dependently drawn towards each other to cause said at least one cutting blade of each of said first pruning head and said second pruning head to shear through successive tree limbs to sever them from the trunk. A method as claimed in anyone of claims 53 to 56 wherein said first and second pruning heads are co-dependently drawn towards each other to cause said at least one cutting blade of said first pruning head and said second pruning head to iteratively shear through successive tree limbs to sever them from the trunk. A method of pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said method comprising: i. capturing a first pruning head to the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk, ii. capturing a second pruning head to the trunk above the first pruning head, said second pruning head comprising at least one blade to locate about and in close proximity to the trunk when said second pruning head is captured to the trunk, iii. causing said first and second pruning heads to move co-dependently in an opposed direction relative to each other in a direction parallel the trunk of the tree so that when said first pruning head encounters a said limb it cuts through said limb when said second pruning head encounters one or more other of said limbs. A method of pruning a live tree that has a trunk and a plurality of vertically spaced apart limbs extending outwardly from the trunk to be severed from the trunk, said method comprising: i. capturing a first pruning head to the trunk, said first pruning head comprising at least one blade to locate about and in close proximity to the trunk when said first pruning head is captured to the trunk, ii. capturing a second pruning head to the trunk above the first pruning head, said second pruning head comprising at least one blade to locate about and in close proximity to the trunk when said second pruning head is captured to the trunk, iii. causing said first and second pruning heads to move co-dependently in an opposed direction relative to each other in a direction parallel the trunk of the tree to each and iteratively cut through limbs of the trunk in an upward and downward direction.