GB2239421A - Cutting tool for tree pruning - Google Patents

Abstract

A cutting tool primarily for tree pruning has a cutter such as a driven rotary saw (2) and jaws (4) carried by a head (1), the jaws (4) being operable for gripping a branch (B) during cutting. The head (1) is mounted on a pole (3) for extended reach operation and the lower end of the pole (3) receives a motor shown conveniently provided by an electric drill (5) for driving a shaft drive (6) to the cutter (2). Operation of the jaws (4) is controlled by a lower lever (70) such as by pull wire connection (7) to the spring loaded jaws (4). The pole 3 is of sectional construction (30) for length variation or storage and shoulder sling support (8) is provided at the lower end of the pole (3). <IMAGE>

Description

Title: Cuttina Tool The object of this invention is to provide a power driven cutting tool primarily for extended reach use in pruning trees or the like by cutting or lopping off excess branch growth and whereby convenient operation is afforded usually from ground level or from other support such as a vehicle. The basic tool is also capable of use for other cutting purposes.

According to the invention a pruning or cutting tool is characterised by support means carrying a cutter such as a saw arranged for power driven operation and also carrying adjacent said cutter, gripping means operable for releasably engaging a branch or the like during cutting of the latter by the cutter.

Further in accordance with the invention the support means carrying the cutter and gripping means is mounted or mountable on a pole or the like for extended reach operation, which pole or the like may be arranged to receive at its lower part a source of motive power such as an electric drill or power drive connection for driving the cutter by shaft or other drive.

A practical example of the invention as a pruning tool is shown in the accompanying drawings in which: FIGURE 1 is a side elevation of the tool shown in position of use; FIGURE 2 is an enlarged scale side elevation of the cutting head assembly.

FIGURE 3 is a detail side elevation showing an alternative form of gripping means or jaws and FIGURE 4 is an axial plane section of a typical arrangement of cutting head assembly.

Like parts are referred to by the same or similar reference numerals throughout the drawings.

Alternative arrangements are described later.

A head 1 rotatably carrying a cutter in the form os circular saw blade or disc 2 is mounted on a pole, column or the like 3 for extended reach operation. The head 1 also carries gripping means in the form of a pair of jaws or claws 4 which are arranged to engage a branch B of a tree prior to and during cutting of the branch by the saw blade 2.

For convenient operation the saw blade 2 is shown driven by a source of motive power such as an electric drill 5 carried at the lower end of the pole 3, by means of a shaft 6 shown coaxially contained in the tubular pole 3, the drive being transmitted from the upper end of the shaft 6 to the saw blade spindle by bevel gear mechanism 62 or other suitable driving gear.

As shown the jaws 4 are preferably pivotally mounted coaxially with the saw blade 2 and adjacent one side of the latter either between the blade 2 and the head 1 or at the outer side of the blade 2. The jaws 4 are also spring biassed to a gripping or locating position about a branch B to be cut and for this purpose rearward extensions 40 of the jaws 4 are urged apart at their rear ends by a compression spring 44 whereby the jaws 4 are moved towards one another.

In order to release the jaws 4 from the remaining part of the branch B on the tree after that part of the branch beyond the saw blade 2 has been cut off the jaws 4 are opened against the spring loading 44 by means of a pull wire or cord 7 from a control lever 70 mounted on a lower part of the pole 3.

The pull wire 7 passes through the rear ends of jaw extensions 40 and through the spring 44 to an anchorage or a head or nipple 74 at the outer side of the upper extension 40. The wire 7 also passes through a stop member 14 fixed on the head 1 and which provides an abutment for the lower extension 40 as the extensions 40 are drawn towards one another by the action of the pull wire 7.

The control lever 70 is shown conveniently pivotally carried by a handle 73 on the pole 3 and the pull wire 7 may be guided by one or more guides or eyes 37 mounted from the pole 3.

In use the jaws 4 are engaged about a branch at a required cutting off position and the saw blades 2 is driven by the drill 5 to cut through the branch B after which the jaws 4 are released from the remainder of the branch by operation of the lever 70. During cutting the saw blade 2 is fed through the branch B by appropriate pressure on the pole 3 by the operator and which is assisted by the spring loaded action of the jaws 4 as they further engage about the branch B. For this purpose the jaws 4 are shown of curved form in an opposed or caliperlike formation to progressively engage about the branch B and accommodate branches of different size within the capacity of the jaws 4 as well as being self adapting to irregular shapes of the branches due to bark and protuberances.The forward ends of the jaws 4 are shown having outwardly directed lead in or ride over portions 41 to facilitate initial engagement about a branch B and prevent the jaws 4 from digging into the branch or being otherwise hindered against required engagement. The jaws 5 may be of serrated, toothed or spiked form at their opposed edges for non-slip engagement about a branch.

During use an operator holds the handle 73 by one hand and holds or steadies the drill 5 with the other hand and by which the drill trigger 51 and any trigger locking button 52 are operated.

For convenience in such use and to relieve some extent of hand held weight of the complete tool, the drill 5 or lower end part of the pole 3 may be slung from a shoulder of the operator e.g. by the shoulder strap 8 which is shown connected to a holster 85 holding the drill 5.

The saw blade 2 should be of a suitable diameter for cutting through the usual branch sizes encountered during pruning, bearing in mind that just under half the diameter of the blade 2 is able to pass through the branch B. However, where larger sizes of branch require to be cut and which are within the capacity of the jaws 4, the branch can be cut into as far as possible from one side and then the tool re-engaged with the branch for cutting into from the other side until the branch is fully cut through. The procedure should be such that the second or final cut is effected with the jaws 4 engaged about the remainder of the branch or the tree. However the arrangement may be such that the jaws 4 grip the cut off portion of the branch for control of the latter and lowering it to the ground by the tool.

For convenience in marketing, storing and transporting the complete tool and also to provide for variation in length, the pole 3 is shown of sectional construction and in the example shown in the drawings, three sections 30 are provided connected by connectors 31 which also accommodate couplings 61 for rotationally fast connection of corresponding sections 60 of the drive shaft 6. Since the upper and lower sections 30 are connected, or adapted to be connected, to the head 1 and drill 5 respectively, interchangeable intermediate sections 30 of different length may be employed or one or more intermediate sections used according to the extended reach required and within practical limits. If desired the pole 3 or a part of it may be otherwise extendible such as by telescopic construction.

The lower end of the pole 3 or pole section 30 is shown secured to the drill 5 by a sleeve 35 which is clamped about the usual spigot 53 at the forward end of the drill casing 55, the sleeve 35 being slotted or gapped at 350 for operating key access to the drill chuck 50 which latter receives the lower end of the drive shaft 6 or section 60 thereof.

In view of their ready availability an electric drill 5 provides a convenient drive of adequate power and where mains electric current supply is not available may be operated from a battery or generator set. Other suitable forms of electric motor drive may be employed or alternatively a small petrol or other internal combustion engine may be used as the power source. Hydraulic or pneumatic motor drive are further alternative sources as well as flexible shaft drive from a suitable power take off facility.

If desired jaws 41 (Figure 3) of a larger size in relation to the saw blade 2 and of a more pronounced curvature may be employed and which embrace or contain a branch B in relation to the blade 2. For this purpose the leading ends 411 of the jaws 41 overlap in the closed condition. As before the jaws 41 are spring urged in the closing direction by a compression spring 44 acting between rearward extensions 401 of the jaws 41 and they are opened against the spring loading by Bowden cable 77 of which the inner wire 78 is connected to the upper extension 401 and the outer casing 79 abuts the lower extension 401.

Figure 4 shows a typical practical arrangement of cutting head assembly showing in particular the axial disposition of the jaws 41 and saw blade 2 and the bevel gear drive 621 to the latter from the shaft 6.

Whereas spring loaded closing of the jaws 4 is preferred, for a self accommodating yieldable gripping action, they may be spring urged to the open condition and positively brought towards one another by pull wire or similar operation.

Alternatively the jaws 4 may be positively operated in both directions by push/pull rod operation. In a further arrangement one jaw may be fixed on the head 1 and the other jaw operated in any of the ways described above.

Instead of a rotary circular saw blade 2 a similarly driven chain saw may be used or a reciprocating cutter may be employed driven by cam or crank mechanism from the driving power source e.g. from the shaft 6. The saw blade 2 chain saw or reciprocating cutter may be operable for feeding and any retracting movement relative to the jaws 4 or the like by suitable separate mounting in obtaining a required cutting action.

In yet another development the head 1 may carry preferably an electric motor of minimum weight for directly driving the saw blade 2 chain saw or reciprocating cutter, thus dispensing with a shaft drive 6. In such a case the motor could be controlled by a switch at the lower end part of the pole 3.

Although a cutting tool according to this invention is primarily intended for tree or like pruning purposes it may be used for other purposes such as cutting timber or logs e.g. on a saw bench where the jaws 4 or the like serve to hold or steady the work relative to the cutter. For such use the drill 5 may be directly connected to the head 1 in an attachment arrangement with lever or like provision on the head for operation of the jaw or jaws 4 as necessary. For such use and where the head 1 carries a direct motor drive to the cutter a handle or handles would be provided mounted or mountable on the head.

The tool may also be used for underwater cutting purposes to some depth e.g. for cutting away weeds or submerged protuberances such as roots or the like by means of the cutter 2 and jaws 4, the inverted tool being operated by the pole 3 from a boat or river bank or lakeside. In such a case and unless adequate electrical safety measures are taken, mains current or similar electric power supply to an electric motor drive 5 to the cutter 2 should be avoided and a low voltage (e.g. 12 volts) supply preferably employed to an appropriate electric motor or a petrol motor or other non-electric drive may be used.

It is to be understood that various modifications may be made to the construction of the cutting tool within the scope of the invention herein defined.

Claims (16)

Claims

1. A pruning or cutting tool characterised by support means carrying a cutter such as a saw arranged for power driven operation and also carrying adjacent said cutter, gripping means operable for releasably engaging a branch or the like during cutting of the latter by the cutter.

2. A pruning or cutting tool according to claim 1 wherein the gripping means comprises a pair of opposed jaws or claws at least one of which is operable for effecting gripping of a branch or the like between them or for their release therefrom.

3. A pruning or cutting tool according to claim 2 wherein one or both of the jaws or claws is or are spring biased for effecting gripping of a branch or the like between them and is or are positively operable for their release therefrom or vice versa.

4. A pruning or cutting tool according to claim 2 or 3 wherein one or both of the jaws or claws is or are pivotally carried by the support means.

5. A pruning or cutting tool according to claim 4 wherein the cutter consists of a rotary or circular saw and one or both of the jaws or claws is or are pivotally mounted on the support means about the axis of rotation of the cutter for their relative gripping or release movement.

6. A pruning or cutting tool according to any of the preceding claims wherein the gripping means such as the pair of jaws or claws are carried by the support means adjacent the cutter for either gripping the remainder of a branch or the like during cutting or for gripping that portion of the branch or the like which is being cut off.

7. A pruning or cutting tool according to any of claims 2 to 6 wherein the pair of jaws or claws are of curved form in an opposed or caliper-like formation for engagement about a branch and to accommodate within their capacity branches of varying size and/or shape.

8. A pruning or cutting tool according to any of the preceding claims wherein the support means carrying the cutter and gripping means such as the pair of jaws or claws is mounted or mountable on a pole or the like for extended reach operation.

9. A pruning or cutting tool according to claim 8 wherein the pole or the like is arranged to receive at its lower part a source of motive power or power drive connection for driving the cutter by shaft or other drive.

10. A pruning or cutting tool according to claim 9 wherein the lower part of the pole or the like is arranged to receive a source of motive power in the form of an electric drill for lower manually controlled drive to the cutter.

11. A pruning or cutting tool according to any of claims 8 to 10 wherein the lower part of the pole or the like carries control means for controlling the operation of the gripping means or pair of jaws or claws such as by pull wire, cord, cable or rod connection thereto.

12. A pruning or cutting tool according to any of claims 8 to 11 wherein the pole or the like is of variable length construction for providing variation in the extent of extended reach operation required and/or for storage or like purposes.

13. A pruning or cutting tool according to claim 12 wherein the pole or the like is of sectional or telescopic construction.

14. A pruning or cutting tool according to any of claims 8 to 13 wherein sling means is provided for supporting the pole or the like at its lower part from a shoulder of a person during operation of the tool.

15. A pruning or cutting tool according to claim 14 wherein the sling means comprises a sling or strap attached to a holster which is arranged to engage about an electric drill or other motor drive when received by the lower part of the pole or the like.

16. A pruning or cutting tool when substantially as herein described with reference to the accompanying drawings.