GB2476467A

GB2476467A - Apparatus for cutting hedges

Info

Publication number: GB2476467A
Application number: GB0922382A
Authority: GB
Inventors: Andrew Pullan; Natalie Grayson; Brian Allott
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-12-22
Filing date: 2009-12-22
Publication date: 2011-06-29
Anticipated expiration: 2029-12-22
Also published as: GB0922382D0; GB2476467B

Abstract

Apparatus101for cutting hedges102or vegetation comprises a drive mechanism103, and a main body104mounted on the drive mechanism. An articulated arm105is mounted on the main body. The articulated arm comprises a plurality of portions113,105,106, each portion being pivotally joined to an adjacent one of said portions. The apparatus has mechanical means108,204for causing rotation of one of the portions with respect to an adjacent one of the portions. A cutting tool109is mounted on the articulated arm105. The main body104may be pivotally mounted on the drive mechanism103and the apparatus may further comprise a shaft114supported by the main body104which is rotatable about a vertical axis and an offset arm113is mounted on the shaft114such that the offset arm113is able to swing about a first axis. The articulated arm105may have an end portion extending along a swivel mounting110which is connected to the cutting tool109so that the tool can be rotated about the mounting.

Description

Apparatus for Cutting Vegetation

CROSS REFERENCE TO RELATED APPLICATIONS

This application represents the first application for a patent directed towards the invention and the subject matter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus for cuffing vegetation, and particularly such apparatus having an articulated arm supporting a cuthng tool.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided apparatus for cutting vegetation, said apparatus comprising a drive mechanism for propelling the apparatus over the ground in a first direction; a main body mounted on said drive mechanism; an articulated arm mounted on said main body, said articulated arm comprising a plurality of portions, each said portion being pivotally joined to an adjacent one of said portions; mechanical means for causing rotation of one of said portions with respect to an adjacent one of said portions; and a cutting tool mounted on said articulated arm.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Figure 1 shows apparatus 101 embodying the present invention; Figure 2, 3 & 4 show the apparatus 101 in a storage position in the side view, plan view and perspective view respectively; Figure 5 shows a partial front view of the apparatus 101; Figure 6 shows a perspective cross-sectional view of articulated arm of the apparatus 101; Figure 7 shows a partial perspective cross-sectional view of the main body 104, offset arm 113 and lower portion 107 of the articulated arm 105; Figure 8 shows the cuffing tool 109 and joint system 110 separate from the articulated arm; Figure 9 shows the joint system 110 with the cutting tool 109 removed; Figure 10 shows a cross-sectional perspective view of the joint system 110; Figure 11 shows A further cross-sectional view of the joint system; Figure 12 shows a front view of the apparatus 101 cutting the top of the hedge 102; Figure 13 shows the apparatus 101 positioned on a sloping ground surface 1301 next to a substantially vertical hedge 1302; Figure 14 shows a schematic representation of the hydraulic system of apparatus 101; Figure 15 shows an alternative apparatus 1501 embodying the present invention; and Figure 16 shows the apparatus 1501 cutting the conical-shaped tree 1502 using an alternative method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 Apparatus 101 embodying the present invention is shown in Figure 1.

The apparatus 101 is suitable for cutting tall hedges, up to approximately six metres tall such as hedge 102. The apparatus 101 comprises a drive mechanism 102 for propelling the apparatus 101 over the ground. A main body Q1AO1r,1 (D 104 is mounted above the drive mechanism 103 and an articulated arm 105 is mounted on the main body. The articulated arm comprises a number of portions, with each of the portions being pivotally joined to at least one other adjacent one of the portions. For example, the articulated arm 105 comprises an upper portion 106 pivotally joined to a lower portion 107. The apparatus is also provided with mechanical means for causing rotation of portions of the articulated arm 105 with respect to adjacent portions. For example, the upper portion 106 may be caused to rotate with respect to the lower portion 107 by means of a hydraulic piston 108.

A cutting tool 109 is mounted on the articulated arm 105 for cutting the vegetation. In the present case, the cutting tool 109 has a pair of blades of known type for cutting a hedge and will be further described below. The cutting tool 109 is mounted at the end of the upper portion 106 of the articulated arm by a joint system 110 that allows the cutting tool 109 to be rotated with respect to the upper portion 106 about three mutually perpendicular axes. The joint system 110 will be described in detail below.

The upper portion 106 and lower portion 107 of the articulated arm 105 are each formed of two elements, such that one of the elements is slidable within the other one of the elements in a telescoping manner. For example, the upper portion 106 is formed of an outer element 111 and an inner element 112 mounted within element 111. As will be further described below, the two elements 111 and 112 are connected by a hydraulic ram such that the inner element 112 can be forced to move out from within the outer element 111 or retracted within the element 111 The inner element may be fully retracted for storage and transportation of the apparatus 101, or retracted either fully or partially when cutting hedges smaller than hedge 102.

The main part 115 of the articulated arm 105, comprising the upper portion 106 and lower portion 107, is mounted on an offset arm 113. The offset arm 113 extends perpendicularly to a shaft 114 on which it is mounted, the shaft itself being mounted on the main body 104 of the apparatus. As will be described below, means are provided to rotate the offset arm 113 with respect s to the main body 114, and also to rotate the main part 115 of the arm 105 about a substantially vertical axis with respect to the offset arm 113. Moreover, in the present embodiment, the apparatus is arranged such that the main part of the arm falls in a plane that can be kept parallel with the main body 104 of the apparatus. Again, this will be further described below. Thus, having arranged the apparatus 101 parallel to a hedge, such as hedge 102, the apparatus 101 is typically arranged such that the main part 115 of the articulated arm 105 is kept parallel to the hedge 102. In this position, the upper portion 106 of the articulated arm 105 may be rotated with respect to the lower portion 107 causing the cuthng tool 109 to be swept over side of the hedge 102 in a plane that is generally parallel to the hedge 102.

As illustrated in Figure 1, a lower portion of the apparatus, including the drive mechanism 103, is provided with legs 116 and 117 which terminate in jockey wheels 118. The legs 116 and 117 and wheels 118 provide the apparatus 101 with further stability during the hedge cutting operation.

In the present embodiment, the apparatus 101 is powered by a petrol engine 119 which provides the motive force for the drive mechanism 103 and the power for a pair of hydraulic pumps (not shown) that are located within the apparatus 101.

In the present embodiment, the drive mechanism comprises a pair of continuous tracks of the type commonly found on mechanical digging equipment. However, alternative embodiments are envisaged in which the continuous tracks are replaced by wheels.

The apparatus 101 further comprises a control unit 120 having a plurality of switches 121 for allowing a user to control solenoid-operated valves of the hydraulic system of the apparatus 101. As illustrated, the control unit is located separate to the remainder of the apparatus 101, with the cable 121 providing the communication link. Thus in use, a person using the apparatus 101 typically stands a safe distance from the main body 104 and articulated arm 105, operating the apparatus 101 remotely, by providing user inputs to the control unit 120.

In the present embodiment, the control unit 120 provides electrical signals to the hydraulic valves via electrical cable 122. However, in an alternative embodiment, the control unit 120 is provided with a radio connection to a control unit on the apparatus 101 for providing the necessary signals to the hydraulic valves.

Figures 2, 3 & 4 The apparatus 101 is shown in a storage position in the side view, plan view and perspective view of Figures 2, 3 & 4 respectively.

The articulated arm 105 of the apparatus 101 is shown in its storage position in Figures 2, 3 and 4. Consequently, the main part 115 and the offset arm 113 of the articulated arm 105 have been arranged such that they each lie substantially in the same vertical plane, which extends along the length of the main body 104 of the apparatus 101 from its front end to its back end.

In this storage position, the inner element 112 is telescopically folded away within the outer element 111 to minimise the length of the upper portion 106. Similarly, the inner element 212 of the lower portion 107 of articulated arm 105 is almost entirely located within the outer element 211.

The upper portion 106 has been rotated about a pivot pin 201 connecting the upper portion to the lower portion 107 of the articulated arm 105, such that the upper portion 106 is substantially parallel to the lower portion. To achieve this, the hydraulic ram 108 has been fully extended.

The main part 115 of the articulated arm 105 is mounted by means of a second pivot pin 202 to a substantially vertical shaft 203. The pivot pin 202 being arranged to allow rotation of the main part 115 about a substantially horizontal axis through the pivot pin 202.

A hydraulic ram 204 provides a means of causing relative rotation of the lower portion 107 with respect to the shaft 203. In Figure 2, the cylinder 204 is shown in its most contracted position such that the lower portion 107 is substantially horizontal position.

The shaft 203 is supported at the end of the offset arm 113 in bearings 205, such that the shaft 203 extends perpendicular to the offset arm 113. The lower portion 107 and shaft 203 may be rotated within the bearings 205 to swing the lower portion 107 away from the offset arm 113. As will be described below, a chain and sprocket mechanism 206 is provided for causing such a pivotal rotation.

The offset arm extends to either side of the shaft 114 that supports it.

The main part 115 of the articulated arm 105 is supported at one end of the offset arm 113 while a counter-weight 206 is supported at its other end to provide the apparatus 101 with improved balance.

A lower part 207 of the apparatus 101, which comprises the drive mechanism 103, is provided at its uppermost surface with a series of vertically extending plates 208. The main body 104 is similarly provided with vertically extending plates on its lower surface, and the two sets of plates are connected by a pivot pin 209, such that the main body 104 is pivotable about the lower part 207 of the apparatus 101. A hydraulic ram 210 connects the main part 104 and the lower part 207 of the apparatus 101, so that actuation of the hydraulic ram 210 causes the main body 104 to lotate about the pivot pin 209 with respect of the lower part 207 of the apparatus 101. These components form the basis of a self-levelling mechanism, which will be further described with respect to Figure 5.

As shown in the plan view of Figure 3, the apparatus 101 has a leg 116 extending to its left and right sides. The legs 116 are pivotably attached to the lower part 207 of the apparatus 101 such that they may be swung out to their fully extended position as shown in Figure 3 or may be swung inwards into a storage position. The third leg 117 extends forwards of the apparatus 101 and comprises an inner part 221 extending from within an outer part 222. The leg 117 is shown in its fully extended position in Figure 4 but the inner part 221 may be slid within the outer part 222 into a storage position. A latching pin (not shown) is provided to maintain the inner part 221 in either its extended or storage position.

A jockey wheel 118 is located at the end of each of the three legs 116, 117. The jockey wheel 118 is of a type commonly found on caravans and consequently has a handle 223 which may be rotated to adjust the height position of the wheel 118 with respect to the respective leg 116, 117.

Figure 5 A partial front view of the apparatus 101 is shown in Figure 5. The front leg 117 and its wheel 118 have been eliminated from the Figure in order to provide a clear view of the means by which the main body 104 is mounted on the lower part 207 of the apparatus 101.

As mentioned previously, a number of vertically extending plates 208 extend upwards from an upper surface of the lower part 207 of the apparatus 101. Similarly, vertically extending plates 501 attach to the main body 104 extend downwards from the main body. The pin 209 passes through the two sets of plates 208 and 501 such that the main body 104 is pivotally mounted above the lower part 207 of the apparatus 101. As illustrated in Figure 5, the hydraulic ram 210 is attached at its upper end to the main body 104 and to the lower part 207 of the apparatus 101 at its lower end, and is located to one side of the axis of the pivot pin 209. Consequently, extension of the hydraulic ram 210 causes the main body 104 to rotate to the left (as viewed from the front) with respect to the lower part 207 of the apparatus 101. Similarly, contraction of the hydraulic ram 210 causes the main body 104 to rotate to the right (as viewed from the front) with respect to the lower part of the apparatus 101.

The hydraulic ram 210 is powered by hydraulic fluid received from a hydraulic valve. The hydraulic valve is actuated by solenoids that are themselves energised by electrical circuitry including mercury switches. The mercury switches (not shown) are located on the main body 104. One of the mercury switches closes if the main body 104 is tipped to the left of vertical and the other one of the two mercury switches is closed if the main body 104 is tipped to the right of vertical. Thus, the mercury switches close an electrical circuit which energises a solenoid of the hydraulic valve causing the hydraulic piston of cylinder 210 to be moved until the main body 104 is positioned in a vertical orientation.

It will be understood that the offset arm 113 and main part 115 of the articulated arm 105 will be rotated along with the main body 104 when the hydraulic ram 210 is operated. Consequently the action of the hydraulic ram 210 also causes the main part 115 of the articulated arm to maintained in a vertical plane.

Figure 6 A perspective cross-sectional view of upper parts of the apparatus 101 is shown in Figure 6. As mentioned previously, the upper portion 106 of the articulated arm 105 comprises an inner element 112 that is slidable within an outer element 111. Each of the elements Ill and 112 in the present embodiment comprise of rectangular section tubular elements, and the inner element 112 may be caused to slide within the outer element 111 by the action of a hydraulic ram 601 located within the inner element 112.

Similarly, the lower portion 107 is formed of the inner element 212 that is slidable within the outer element 211 under the action of a hydraulic ram 602, located within the inner element 112.

As may be seen in Figure 6, the joint system 110 comprises cylinder block 603 fixed within the end of the inner element 112 of the upper portion 106. The joint system 110, including the cylinder block 603 will be described in detail below.

In the present embodiment, the hydraulic rams 601 and 602 used to extend the upper portion 106 and lower portion 107 of the arm 105. However, in an alternative embodiment, the arm is formed of telescoping box sections having a smaller cross-section and the hydraulic rams used to extend the length of the arm are mounted external to, and parallel to, the box-sections forming the arm. Such an embodiment is shown in Figure 15 and 16.

Figure 7 A partial perspective cross-sectional view of the main body 104, offset arm 113 and lower portion 117 is shown in Figure 7.

The offset arm 113 is rigidly fixed to the upper end of the shaft 114, which is itself supported within bearings 701 fixed to the main body 104. The shaft 114 has a cylindrical bore through which extends a second shaft 702 that is itself mounted within bearings 703 within the main body 104. It should be understood that the shafts 701 and 702 are rotatable within their bearings with respect to each other.

The outer shaft 114 is rigidly fixed within a pinion 704, which is located within the main body 104. The pinion 704 engages a toothed rack 705. The rack is movable under the action of a hydraulic ram 706 that is mounted to a wall of the main body 104. Thus, operation of the hydraulic ram 706 moves the rack 705 causing rotation of the pinion 704, shaft 114 and offset arm 113.

In the present embodiment the rack 705, pinion 704 and offset arm 113 are arranged such that when the rack 705 is fully retracted the offset arm 113 is swung to the right of the main body 104. Similarly, when the rack is pushed to its fully extended position the offset arm is swung to the left of the main body 104. Thus the articulated arm may be positioned to be operated either to the left or the right of the main body 104.

The shaft 702 has an upper portion 707 located within the bore of the outer shaft 114, and a lower portion 708 extending from the lower end of the shaft 114. The lower portion 708 of the shaft 702 is rigidly fixed within a second pinion 709 that engages a second toothed rack 710. The toothed rack 710 is connected to the piston of a hydraulic ram 711, fixed to the main body 104.

The upper end of the shaft 702 has a sprocket 712 rigidly fixed to it, and a similar sprocket 713 is fixed to the shaft 203, which supports the main part of the articulated arm 105. A continuous chain 714 extends around the two sprockets 712 and 713 such that rotation of sprocket 712 causes rotation of sprocket 713. Thus, actuation of hydraulic ram 711 causes linear movement of the toothed rack 710, resulting in rotation of the pinion 709, shaft 702, sprocket 712, sprocket 713, shaft 203 and main part 115 of the articulated arm 105.

This arrangement also provides a mechanism by which the offset arm 113 may be rotated with respect to the main body 104 while maintaining the relative orientation of the main part 115 of the articulated arm with respect to the main body 104. Specifically, this is achieved by operation of hydraulic ram 706 while keeping the position of hydraulic 711 fixed. Operation of the hydraulic ram 706 causes rotation of the offset arm 113, but because the sprocket 712 is prevented from turning by the stationary hydraulic ram 711, the action of the chain 714 on the sprocket 713 maintains the orientation of the shaft 203 with respect to the main body 104. Thus, if the main part 115 of the articulated arm starts in a position parallel to the main body 104, the main part will remain parallel with the main body 104 while the offset arm 113 swings away from the main body 104.

Figure 8 The cutting tool 109 and joint system 110 are shown separate from the articulated arm in Figure 8.

The cuffing tool 109 comprises a pair of toothed blades 801 of known type for cutting hedges, such as privet hedges, conifers, etc. The upper of the two blades 801 is moved in a reciprocating manner by a hydraulic motor 802.

The cutting tool 109 is mounted on a rotatable shaft 803 that forms part of the joint system 110. The shaft 803 extends along a swivel axis 804, which in the present embodiment extends parallel to the length of the blades 801. Thus, by rotation of the shaft 803, the cutting blades 801 may be made to swivel about the swivel axis 804 as indicated by arrow 805.

The shaft 803 is driven by a reversible electric motor 806 via a worm and wheel mechanism 807 that will be further described below.

The worm and wheel mechanism 807 is itself rigidly mounted on a U-shaped element 808 that is pivotally mounted on a second U-shaped element 809 such that the first U-shaped element 808 is rotatable about two perpendicular axes 810 and 811. Such movement is caused by the action of one or both of two hydraulic rams located within the cylinder block 603, as will be described further below, It will be understood that such movements would cause the cutting tool 109 to be rotated up or down and/or left or right about the axis 811 and 810 respectively.

In the present embodiment, the cutting tool comprises a hedge cutting type tool. However, in an alternative embodiment, the cutting tool is replaced by a tool having a rotating blade of a type known for use when cutting grass.

Such a grass-cutting tool, when supported by the articulated arm 105, is used to cut grass on sloping banks, and other such surfaces that cannot be accessed by conventional lawn mowers. When used in this manner, the apparatus 101 is located on relatively horizontal ground to one side of the sloping bank and the articulated arm 105 is extended and used to manoeuvre the grass-cutting tool over the grassy surface. Other alternative embodiments are also envisaged in which the cutting tool comprises a lopper head or a chainsaw.

Figure 9 The joint system 110, with the cutting tool 109 removed, is shown in further detail in Figure 9.

As previously described, the worm wheel mechanism 807 is mounted on a first of two U-shaped elements 808, a shaft 901 is rigidly fixed across the ends of the U-shaped element 808 such that rotation of the shaft 901 about its axis 810 results in similar rotation of the U-shaped element 808. A first bevel gear 902 is rigidly fixed to the shaft 901 such that the gear 902 and shaft 901 rotate together.

The shaft 901 extends through a second shaft 903 such that the first shaft 901 is able to rotate within the second shaft 903. The second shaft 903 extends along the axis 811, perpendicular to the axis 810 along which shaft 901 extends. The shaft 903 is mounted at each of its two ends on the second U-shaped element 809 such that the shaft 903 is pivotable about its axis 810 with respect to the U-shaped element 809. The shaft 901 passes diametrically across the second shaft 903, and so as the shaft 903 pivots about its axis 810, the first shaft 901 is rotated, resulting in rotation of U-shaped element 808.

A second bevel gear 904 is mounted on the shaft 903 such that it is free to rotate on said shaft. The second bevel gear 904 meshes with the first bevel gear 902 so that rotation of the second bevel gear 904 will cause rotation of the first bevel gear 902 and similar rotation of the first U-shaped element 808.

The second U-shaped element 809 is rigidly mounted on posts 905 that are themselves rigidly fixed to the cylinder block 603. The cylinder block 603 contains two hydraulic rams (one of which, 1001, is shown in Figure 10). Each of the two hydraulic rams contains a piston from which extend a pair of rods.

Thus, one cylinder is provided with a pair of rods 906A and 906B while the other of the two pistons is provided with rods 907A and 907B. In each case, one of the two rods 906A, 907A extend from the cylinder block 603 towards the U-shaped element 809, while the other of the two rods 906B, 907B extend from the cylinder block away from the U-shaped element 809.

A first control cable 908 is fixed at each of its two ends to the ends of the rods 906A and 906B. The control cable 908 extends from the rod 906A up and around the bevel gear 904, back down through a hole provided through the cylinder block 603, around a pulley wheel 909 mounted on a post on the cylinder block 603 and terminates at the rod 906B.

Similarly, a second control cable 910 is attached at each of its ends to the rods 907A and 907B. From rod 907A the control cable 901 extends up and around the second shaft 903 down through a hole formed in the cylinder block 603 around a second pulley wheel 911 mounted on a post on the cylinder block 603, and terminates at the second rod 907B.

Operation of the first hydraulic ram having a piston connected to rods 906A and 906B linearly moves said rods and causes the first control cable 908 to move around its circuit. In doing so, the cable 908 turns the second bevel gear 904 which causes rotation of the first bevel gear 902 and similar rotation of the shaft 901 and U-shaped element 808. Consequently, such an action of the first hydraulic ram causes rotation of the cutting tool 109 about the axis 811. It will be understood that depending upon whether or not the piston within the first hydraulic ram is moved up or down, the cutting tool will be rotated up or down around the axis 811.

Operation of the second hydraulic ram causes linear movement up or down of the rods 907A and 907B and so causes movement of the second control cable 910 around its circuit. When the second control cable is moved it acts upon the second shaft 903 such that the second shaft 903 pivots about its axis 810. When the second shaft 903 swivels in this manner it causes a length wise rotation of the shaft 901 and similar rotation of the first U-shaped element 808 about the axis 810. Thus, operation of the second hydraulic ram causes the cutting tool 109 to rotate left or right about the axis 810, depending upon the sense of movement of the second hydraulic ram.

Figure 10 A cross-sectional perspective view of the joint system 110 is shown in Figure 10. The cross-section is taken through the second cylinder 1001 to which are attached the rods 907A and 907B. Figure 10 also illustrates one of the holes 1002 that extends through the cylinder block to allow passage of the control cable 908.

Figure 11 A further cross-sectional view of the joint system 110 is shown in Figure 11. The cross-section is taken perpendicular to the axis 804 of the shaft 803 on which the cutting tool 109 is mounted. The cross-section also cuts through the worm wheel mechanism 807 and electric motor 806.

A toothed wheel 1101 is mounted on the shaft 803 and a worm screw shaft 1102 defines a helical groove with which the teeth of the wheel 1101 interact. A second toothed wheel is provided on the shaft 1102 that similarly interacts with a second worm (not shown). This second worm is driven by electric motor 806. In operation, the electric motor 806 drives the second worm, which drives the second toothed wheel mounted on the shaft of the first worm 1102 and so drives the first wheel 1101. It will be understood that a suitable arrangement of these gears, the shaft 803 is rotated through a small angle when compared to the angular movement of the motor 806. Thus, the cutting tool 109 may be accurately swivelled around the axis 804 by the operator of the apparatus 101.

Figure 12 A front view of the apparatus 101 cutting the top of the hedge 102 is shown in Figure 12.

The cuthng tool 109 has been rotated about axis 811 such that the blades 801 extend substantially perpendicular to the upper portion 106 of the articulated arm 105. In addition, the cutting tool 109 has been swivelled about its axis 804 so that the blades 801 are arranged parallel to the ground surface 1201 so that the top of the hedge 102 may be cut flat and parallel with the ground surface 120 by forward movement of the apparatus 101.

It should be understood that the cutting tool may be moved about many different axes, and moved about many different combinations of axes while cutting a hedge. Consequently a hedge may be cut in many different ways. For example, the offset arm 113 may be positioned perpendicular to the hedge and the main part 115 of the arm 105 may be swung to the left and right about the shaft 203 in order to cut a horizontal surface at the top of the hedge.

Figure 13 The apparatus 101 is shown positioned on a sloping ground surface 1301 next to a substantially vertical hedge 1302. The offset arm 113 has been swung away form the main body 104 of the apparatus 101 while the main part of the articulated arm 105 has been maintained parallel to the hedge 1302. In particular, the main part 115 of the articulated arm 105 has been maintained in a vertical plane by operation of the self-levelling system of the apparatus 101. Specifically, one of the mercury switch within the main body 104 was closed due to tilting caused by the sloping ground 1301. Closing of the mercury switch energised a solenoid hydraulic valve, which caused the hydraulic ram 210 to retract. This movement brought the main body 104 level with the horizontal and thereby caused the main part 115 of the articulated arm to reside in the vertical plane.

It will be understood that maintenance of the main part 115 in a vertical plane allows for ease of operation of the cutting tool 109 in order to obtain substantially vertical sides to the hedge 1302 when cutting it.

Figure 14 A schematic representation of the hydraulic system of apparatus 101 is shown in Figure 14. A first hydraulic pump 1401 provides a flow of hydraulic fluid from a tank 1402 to a pressure line 1403. A dump valve 1404 is connected to the pressure line 1403 and, in the event that none of the hydraulic rams of apparatus 101 are being operated, the hydraulic fluid is returned back to the tank 1402 via the dump valve 1404. The dump valve 1404 is arranged to be closed if one of the hydraulic rams is operated, so that full hydraulic pressure is supplied to that hydraulic ram.

The nine hydraulic rams of the apparatus 101 are shown schematically in Figure 14 along with their controlling valves. The hydraulic rams have been numbered as shown in the previously described Figures. (The hydraulic ram 1405 shown in Figure 14 is the second hydraulic ram of cylinder block 603, which controls movement of the rods 907A and 907B.) Each of the hydraulic rams 1001, 601, 602, 706, 1405, 108, 204, 711 and 210 are controlled by a corresponding solenoid-operated four-port three-position hydraulic valve 1406, 1407, 1408, 1409, 1410, 1411, 1412, 1413 and 1414 respectively.

Each of the hydraulic valves 1406 to 1414 has an input port connected to the hydraulic pressure line 1403 and a return port 1415 connected to a return line to the tank 1402. The valves 1406 to 1414 each have a pair of ports 1416 and 1417 connected to their respective hydraulic rams via flow control valves 1418. The flow control valves 1418 have been manually pre-set to allow a restricted flow of hydraulic fluid to the respective hydraulic ram. The restriction to the flow is set such that for valves 1406 to 1413 controlled movement of the hydraulic ram is manageable by the operator. Similarly for the self-levelling system, the restriction to flow moderates rate of movement of the hydraulic ram 210 so that it is able to smoothly rotate the main body 104 of the apparatus into the upright position.

The apparatus 101 comprises a second hydraulic pump 1419 providing a flow of hydraulic fluid from the tank 1402 to the hydraulic motor 802 of cutting tool 109. The pump 1419 provides hydraulic fluid to the motor 802 via a four-port three-position valve 1420. The valve 1420 is arranged such that in its closed position it returns hydraulic fluid back to the tank 1402.

If the valve 1420 is moved to a first position, hydraulic fluid is provided to a first port of the hydraulic motor 802 such that the motor 802 operates in a forward direction. If the valve 1420 is moved to a second open position it supplies hydraulic fluid to a second port of the motor 802 to cause the motor to operate in a reverse direction. The operation of the motor in the reverse direction is useful when the cutting tool becomes jammed on a branch of the vegetation it is cutting. The reversal of the motor pulls the blades away from the branch, and so allows the cutting tool to be repositioned.

In the present embodiment, the articulated arm 105 is moved by hydraulic rams. However, alternative embodiments are envisaged in which one or more of the hydraulic rams of the apparatus are replaced by pneumatic cylinders.

Figure 15 An alternative apparatus 1501 embodying the present invention is shown in Figure 15. The apparatus 1501 is essentially the same as apparatus 101 except that the main part 1515 of the articulated arm 1505 is formed of box sections having a smaller cross-section, and also the hydraulic rams 1561 and 1562 used to extend the upper portion 1516 and the lower portion 1517 of the arm 1505 are mounted externally to the box sections. As a result of this construction, the arm 1505 of apparatus 1501 is lighter than that of apparatus 101. However, in all other aspects, apparatus 1501 is the same as apparatus 101 and operates in the same manner.

In Figure 15, the apparatus 1501 is shown being used to cut a conical-shaped tree 1502. The arm 1505 has been manoeuvred such that it extends within a plane that is perpendicular to the surface of the tree that it is being cut, and the cutting tool 109 has been rotated about axis 811 so that the blades 801 are arranged at the required angle of slope of the conical tree. The tree may be cut by operating the cutting tool 109, while the apparatus 1501 is driven in a circle about the tree 1502. Having driven completely around the tree 1502, the arm 1505 is adjusted such that the cutting tool 109 is brought to a different height and rotated about axis 811 to bring the blades 801 to the required angle. The apparatus is then driven around the tree again while operating the cutting tool 109. This process is repeated until the tree has been trimmed as required.

Figure 16 The apparatus 1501 is shown cutting the conical-shaped tree 1502 using an alternative method in Figure 16. The arm 1505 is extended such that the end 1601 of the arm is located to one side of the top 1602 of the tree 1502.

The cutting tool has been rotated about axis 810 so that the blades 801 extend substantially perpendicularly to the upper part 1516 of the arm 1505. The cutting tool 109 has also been rotated about axis 805 so that the width of the blades 801 extends substantially parallel to the slope of the conical tree 1502.

The tree is then cut by operating the cuthng tool 109 while simultaneously moving the upper portion 1516 and lower portion 1517 of the arm 1505 downwards in a scissor-like motion such that the end 1601 of the arm 15O5 follows the slope of the tree 1502. The cutting tool 109 is also rotated about axis 805 in order to maintain the orientation of the blades 801 substantially parallel to the surface of the tree 1502.

Claims

Claims 1. Apparatus for cutting vegetation, said apparatus comprising: a drive mechanism for propelling the apparatus over the ground in a first direction; a main body mounted on said drive mechanism; an articulated arm mounted on said main body, said articulated arm comprising a plurality of portions, each said portion being pivotally joined to an adjacent one of said portions; mechanical means for causing rotation of one of said portions with respect to an adjacent one of said portions; and a cutting tool mounted on said articulated arm.
2. Apparatus for cutting vegetation according to claim 1, wherein said drive mechanism comprises a pair of continuous tracks.
3. Apparatus for cutting vegetation according to claim 1, wherein said drive mechanism comprises wheels driven by an engine.
4. Apparatus for cutting vegetation according to any one of claims I to 3, wherein said mechanical means comprises a hydraulic ram.
5. Apparatus for cutting vegetation according to any one of claims I to 4, wherein said main body is pivotally mounted on said drive mechanism and said apparatus comprises self-levelling mechanism for adjusting the rotational position of said main body with respect to said drive mechanism to maintain said main body in an upright position.
6. Apparatus for cutting vegetation according to any one of claims I to 5, wherein said apparatus further comprises a shaft supported by said main body such that said shaft is rotatable about a substantially vertical first axis, and said articulated arm comprises an offset arm mounted on said shaft such that said offset arm is able to swing about said first axis away from said main body.
7. Apparatus for cutting vegetation according to claim 6, wherein said shaft is rotatable by a first rack and pinion mechanism.
8. Apparatus for cutting vegetation according to claim 6 or claim 7, wherein said articulated arm has a main part mounted on said offset arm such that said main part is able to swing about a second axis separate from and parallel to said first axis.
9. Apparatus for cutting vegetation according to claim 8, wherein said apparatus further comprises coupling means for maintaining the main part of said articulated arm in a plane that is substantially parallel to said first direction.
10. Apparatus for cutting vegetation according to claim 8 or claim 9, wherein said shaft is rotatable by a first rack and pinion mechanism and said main part of said articulated arm is rotatable by a second rack and pinion mechanism.
11. Apparatus for cutting vegetation according to claim 10, wherein said shaft is tubular in form and said second rack and pinion mechanism drives a second shaft located within said first shaft.
12. Apparatus for culling vegetation according to claim 11, wherein said second shaft operates said main part by a belt or chain drive.
13. Apparatus for culling vegetation according to any one of claims I to 12, wherein said articulated arm has an end portion extending along a swivel axis; and a swivel mounting mechanism located on said end portion of said articulated arm, wherein said a cutting tool is mounted on said swivel mounting mechanism, such that said cuffing tool is configured to be rotated by said swivel mounting mechanism about said swivel axis.
14. Apparatus for culling vegetation according to claim 13, wherein said swivel mounting mechanism comprises a worm defining a helical groove and toothed wheel engaged by said helical groove.
15. Apparatus for cuffing vegetation according to any one of claims I to 14, wherein said mechanical means comprises a cable driven by a hydraulic ram.
16. Apparatus for cuffing vegetation according to any one of claims I to 15, wherein said articulated arm has a main part comprising two of said portions, and said culling tool is attached to said main part by a joint system allowing said culling tool to be swung with respect to said main part about two non-parallel axes.
17. Apparatus for cuffing vegetation according to claim 16, wherein said two non-parallel axes are substantially co-planar.
18. Apparatus for cutting vegetation according to claim 11 or claim 12, wherein apparatus comprises: a first transverse shaft extending along a first of said two non-parallel axes and supported by said main part such that said first transverse shaft is pivotable about its axis; a second transverse shaft extending along the second one of said non-parallel axes and supported by said first transverse shaft such that said second transverse shaft is pivotable about its axis; and a mounting supported by said second transverse shaft on which said cutting tool is mounted.
19. Apparatus for cutting vegetation according to claim 18, wherein said apparatus comprises a first bevel gear mounted to rotate on said first transverse shaft, and a second bevel gear fixed on to said second transverse shaft, said second bevel gear being arranged to engage said first bevel gear such that rotation of said first bevel gear causes rotation of said second shaft and said cuffing tool.
20. Apparatus for cutting vegetation according to claim 18 or claim 19, wherein said mechanical means comprises a cable driven by a hydraulic ram, and said cable is arranged to rotate said first transverse shaft.
21. Apparatus for cuffing vegetation according to any one of claims 18 to 20, wherein said mechanical means comprises a second cable driven by a hydraulic ram, and said second cable is arranged to rotate said first bevel gear and thereby rotate said second transverse shaft.
22. Apparatus for cutting vegetation, said apparatus comprising: a main body; drive means for moving said main body over the ground in a first direction; a shaft supported by said main body such that said shaft is rotatable about a substantially vertical first axis; an offset arm mounted on said shaft such that said offset arm is able to swing about said first axis away from said main body; a jointed arm mounted on said offset arm such that said jointed arm is able to swing about a second axis separate from and parallel to said first axis; and coupling means for maintaining the jointed arm in a plane that is substantially parallel to said first direction.
23. Apparatus for cutting vegetation, said apparatus comprising: a main body; an articulated arm supported by said main body, said articulated arm having a main part and an end portion attached to said main part by a joint allowing said end portion to be swung with respect to said main part about two non-parallel axes.
24. Apparatus for cutting vegetation according to claim 23, wherein said two non-parallel axes are substantially co-planar.
25. Apparatus for culling vegetation according to claim 23 or claim 24, wherein apparatus comprises: a first transverse shaft extending along a first of said two non-parallel axes and supported by said main part such that said first transverse shaft is pivotable about its axis; a second transverse shaft extending along the second one of said non-parallel axes and supported by said first transverse shaft such that said second transverse shaft is pivotable about its axis; and a mounting supported by said second transverse shaft on which said culling tool is mounted.
26. Apparatus for culling vegetation according to claim 25, wherein said apparatus comprises a first bevel gear mounted to rotate on said first transverse shaft, and a second bevel gear fixed on to said second transverse shaft, said second bevel gear being arranged to engage said first bevel gear such that rotation of said first bevel gear causes rotation of said second shaft and said cutting tool.
27. Apparatus for culling vegetation according to claim 25 or claim 26, wherein said mechanical means comprises a cable driven by a hydraulic ram, and said cable is arranged to rotate said first transverse shaft.
28. Apparatus for culling vegetation according to any one of claims 25 to 27, wherein said mechanical means comprises a second cable driven by a hydraulic ram, and said second cable is arranged to rotate said first bevel gear and thereby rotate said second transverse shaft.
29. Apparatus for cutting vegetation, said apparatus comprising: a main body; an articulated arm supported by said main body, said articulated arm having an end portion extending along a swivel axis; a swivel mounting mechanism located on said end portion of said articulated arm; and a cutting tool mounted on said swivel mounting mechanism, wherein said swivel mounting mechanism is configured to rotate said cutting tool about said swivel axis.
30. Apparatus for cutting vegetation according to claim 30, wherein said swivel mounting mechanism comprises a toothed wheel and a worm driven by a motor, said worm engaging said toothed wheel.
31. Apparatus for cutting vegetation substantially as herein described with reference to the accompanying figures.