GB2202122A

GB2202122A - Vegetation cutting apparatus

Info

Publication number: GB2202122A
Application number: GB08806324A
Authority: GB
Inventors: Ian Robertson
Original assignee: MCCONNEL F W Ltd; FW McConnel Ltd
Current assignee: MCCONNEL F W Ltd; FW McConnel Ltd
Priority date: 1987-03-21
Filing date: 1988-03-17
Publication date: 1988-09-21
Anticipated expiration: 2008-03-17
Also published as: GB2202122B; FR2612363B1; FR2612363A1; GB8806324D0; GB8706756D0

Abstract

A vegetation cutting apparatus mountable on a carrying vehicle and including an implement mounting arm assembly having a first arm (6) pivotally mounted at one end on a carrier plate (5) itself pivoted on a fixed support. The first arm is pivotally connected at its other end to a second arm (7) which has a cutting implement (9) mounted thereon in the region of its free end and pivotable by an angling ram (8). A first ram (15) and a second ram (16) are arranged respectively to raise and lower and to vary the extension of the arm assembly. Compensation rams (17, 18) are connected respectively to the plate (5) and first arm (6) and operable to displace fluid into the angling ram (8), causing it to maintain the implement (9) in a substantially constant attitude during pivotal movement of the plate (5) and arm (6). <IMAGE>

Description

VEGETATION CUTTING APPARATUS.

This invention relates to vegetation cutting apparatus mountable on a carrying vehicle and adapted to be powered from a power source of the vehicle, the apparatus being of the general kind including an implement mounting arm assembly having a first arm pivotally mounted at one end relative to a fixed support and pivotally connected at its other end to a second arm having a cutting implement pivotally mounted thereon in the region of its free end, a first ram arranged and operable to move the arm assembly in a manner such as to raise and lower the implement, a second ram arranged and operable to cause the reach of the arm assembly to be extended and retracted, and an angling ram operable to rotate the implement relative to the arm for adjustment of the implement working attitude.

With an arrangement of this general kind, it is necessary, during a cutting operation, to operate the angling ram when the vertical attitude of the mounting arm assembly is altered, or the reach of the arm assembly extended or retracted, in order to pivot the implement and so maintain it in a substantially constant cutting attitude. It is common practice to provide a separate control lever for the angling ram in addition to respective control levers for the first and second rams, and this can cause undue complication for an operative in synchronising the operation of the three rams during a working operation.

An object of the invention is to provide a vegetation cutting apparatus of the aforesaid general kind in which the number of controls required for the necessary interaction of the rams is reduced and operation thereof correspondingly simplified, as compared with some existing arrangements.

According to the present invention, a compensation ram is connected to a member movable by operation of one of the first and second rams, the compensation ram having a fluid outlet connection with the angling ram and being operable, in response to movement of said member, to cause fluid displacement in the angling ram in order to produce a compensatory change in attitude of said implement.

Preferably, a further compensation ram is connected to a second member movable by operation of the other of the first and second rams, said further ram having a fluid outlet connection with the angling ram and being operable in response to movement of said second member to displace fluid into the angling ram in order to produce a compensatory change in the attitude of said implement additional or alternative to that produced by the compensation ram connected to said first member.

In one convenient arrangement, said first arm is pivoted on a carrier which is itself pivotally mounted on said fixed support and forms one arm of a parallelogram linkage, of which the opposed arm is formed by a portion of said second arm projecting beyond its pivotal connection with said first arm, said linkage also including said first arm and a generally parallel linking arm extending between said projecting second arm portion and being pivoted on the carrier at a location spaced from the first arm pivot, said first ram and one compensation ram acting between the carrier and said fixed support and said second ram and further compensation ram acting between said first arm and the carrier.

The angling ram is conveniently carried by said second arm and may be connected to the implement by way of an angling mechanism which comprises an arm fast for rotation with a shaft and pivotally mounting the implement, said other end of the ram being connected to said shaft by a slave link pivoted relative to the shaft and ram, the second arm being connected to the slave link by a radius arm connected between the second arm and the link, the arrangement being such that the radius of action of the ram is maintained substantially constant during relative pivotal movement between the implement and second arm.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic side view of one form of the vegetation cutting apparatus of the invention mounted on a vehicle, and Figure 2 is a diagrammatic representation of a hydraulic system for controlling the operation of the apparatus of Figure 1.

In Figure 1 of the drawings, there is illustrated a cutting apparatus, indicated generally at 1, in the form of a hedge cutter mounted on the rear of a vehicle, such as a tractor, indicated generally at 2.

The cutting apparatus includes a support frame 3 mounted on the tractor and having a main upright support member 4. To the upper end of the support member, at a location 5A, is pivotally connected a triangular carrier plate 5, to which is pivotally connected, at a location 6A, a first arm 6 of an implement mounting arm assembly which includes a second arm 7 pivotally connected at 7A to an end region of the first arm 6. An implement, illustrated as a hedge cutter head 9 is pivotally mounted in the region of the free end of the arm 7 on a shaft 10 for swinging movement relative to the arm 7 under the control of an angling ram 8 which is connected at one end to the arm 7 and at the other end to the implement by way of an angling mechanism indicated generally at 11.The arm 7 has an extension 7B beyond the pivot 7A and the end of the extension is connected to the carrier 5, at a location 5B spaced from the pivot 6A, by a further arm 26 arranged so that the arms 6, 26, carrier 5 and extension 7B together form a parallelogram linkage between the support 4 and implement 9.

The mechanism 11 includes an arm 12 fast for rotation with the shaft and with the head 9 at a location offset from the shaft. A piston rod 8A of the ram 8 is connected to the arm 12 by a slave link 13 which is pivotally connected at its respective ends to the piston rod 8A and the arm 12. The slave link is connected in turn to the second arm 7 by a radius arm 14 pivoted to the second arm and to the slave link. As is more fully described in our co-pending application No.8618236, the aforesaid angling mechanism enables the ram 8 to pivot the implement 9 through a substantial arc, whilst maintaining a more or less uniform speed of rotational movement of the implment.This is achieved by arranging the positions of the various pivotal connections between the arms 12 and 14 and link 13 and choosing the lengths of the arms and links such that the radius of action of the slave link 13 and thus of the pivotal connection between the piston rod 8A and the slave link, remains substantially constant throughout the full rotational movement of the implement. The speed of rotation of the implement and the actuating force applied by the ram thus also remains substantially uniform.

A first ram 15 is connected between the support 4 and a location 15A on the arm 5 spaced laterally from the pivotal connection 5A of that arm on the support 4, such that extension or contraction of this ram will cause the arm 5 to move angularly about the pivotal connection 5A so as to raise and lower the arm assembly and with it the implement 9 relative to a surface supporting the tractor 2. A second ram 16 is connected to the arm 5 at a location 16A spaced from the connection 6A and to the first arm 6 of the mounting arm assembly at an intermediate location 6B on the latter so that extension and retraction of the ram 16 will alter the angular position of the arm 6 relative to the arm 5.Because of the interconnection of the arms 6, 26, 5 and 7B, in the form of a parallelogram linkage, the effect of such angular movement of the arm 6 will be to cause the arm 7 to move generally laterally of the tractor and thereby extend and retract the reach of the mounting arm assembly. In many conventional arrangements, this would cause the head 9 to move through an arc in a vertical plane so that its orientation to the ground would vary and require correction by operation of the angling ram by the use of a further control.

In the arrangement of the invention a pair of compensation rams 17, 18 are associated respectively with the operating rams 15, 16. The compensation ram 17 is connected between the support member 4 and a location on the arm 5 at the opposite side of the pivotal connection 5A to the point of connection of the ram 15 with that arm. The ram 18 is connected to the arm 5 at a location adjacent the pivotal connection 15A between the ram 15 and that arm and to the arm 6 at a location between the pivotal connection 6A of that arm with the arm 5 and the location of the connection 6B between the ram 16 and the arm 6.

As will be seen more clearly from Figure 2, the compensation rams 17, 18, and angling ram 8 are double acting. The ram 17 has a pair of fluid connections 17A, 17B respectively at either side of a piston 19 of the ram and the ram 18 has a pair of fluid connections 18A, 18B at either side of a piston 20 thereof. The angling ram 8 has a pair of fluid connections 8B, 8C at either side of a piston 8D thereof, the connection 8B being connected to a fluid line 21 leading to a fluid supply unit 22, and also communicating with the rams 17, 18, via the connections 17B, 18B. The connection 8C of the angling ram is connected via a line 23 to the supply unit 22, the line 23 communicating with compensation ram connections 17A, 18A.During operation of either of the rams 15, 16, to move one of the arms 5, 6, movement of these arms will cause fluid to be expelled from one of the connections of the associated compensation ram into the angling ram in order to effect a compensatory movement of the implement 9 via the linkage 11. It will be seen, for example, that as the ram 15 is extended to raise the arm 5 and with it the implement mounting arm assembly, the implement 9 would normally be moved anti-clockwise through an arc and an operative would have to make corresponding corrections by means of the angling ram 8, attempting to synchronise movement of at least the rams 8 and 16 and possibly the ram 15 also.By virtue of the invention, angular movement of the arm 5 in either direction causes displacement of fluid from the compensation ram 17 into the angling ram 8 so as to cause a compensatory movement of the implement 9, without intervention from the operative, such as to maintain the attitude of the implement 9 substantially constant, irrespective of the position of the arm 5. A similar action takes place upon operation of the ram 16 to extend or retract the reach of the mounting arm assembly and fluid will then be displaced from the compensation ram 18 in order to counter the arcuate movement thus imposed upon the implement 9.

Simultaneous operation of the rams 15 and 16, as would often occur in practice, will provide simultaneous compensatory movement of the implement 9 so that the latter is always maintained in an ideal cutting attitude, irrespective of the height or reach of the mounting arm assembly.

It is convenient to use a pair of compensation rams having the same cylinder and rod diameter, which parameters are chosen in relation to the cylinder and rod diameter of the angling ram to produce the desired compensatory movement of the implement. It would, however, be possible to use compensation rams having different dimensions in order that these rams should respectively cause the angling ram to produce differing compensatory movements.

Although the arrangement described incorporates a parallogram connection between the arm 7 and support 4, the invention may readily be applied to an apparatus in which the first and second arms are in the form of a single jointed boom, of which the inner part constitutes the first arm and is mounted on the fixed support, and the outer part constitutes the second arm and carries the implement. In such an arrangement, a lifting ram would act between the support and the inner part of the jointed boom, and an extension ram between the two parts of the jointed boom to extend or retract the outer part of the arm relative to the inner one.

Compensation rams operable respectively by the inner and outer parts of the jointed boom would act to displace fluid to an implement angling ram, as described above.

Either or both of the first and second arms, and particularly the second arm, may itself be divided into two or more mutually pivotable parts actuated by an additional ram connected between each pair of parts.

With such a construction it would be necessary to incorporate a further compensating ram acting between each such pair of parts and having a fluid outlet connection with the angling ram so as to effect compensatory movement of the latter upon pivotal movement between the parts. In one typical example of such an arrangement, the first arm may be a single arm adapted to be pivotally mounted on a support, such as part of a tractor, and the second arm may comprise a pair of pivotally interconnected parts, one such part having its free end portion pivotally connected to the first arm and the other part having an implement mounted in the region of its free end. The second arm would incorporate the aforesaid additional actuating and compensation rams.

In a further modification, which may be applied to any embodiment of the invention, any of the compensation rams may be operatively connected to the member actuating it by a rack and pinion device. Such an arrangement could increase the accuracy of compensatory movement obtained at the angling ram, particularly if this ram is also provided with a similar rack and pinion device.

Claims

CLAIMS.

1. A vegetation cutting apparatus mountable on a carrying vehicle and adapted to be powered from a power source of the vehicle, the apparatus comprising an implement mounting arm assembly having a first arm pivotally mounted at one end relative to a fixed support and pivotally connected at its other end to a second arm having a cutting implement pivotally mounted thereon in the region of its free end, a first ram arranged and operable to move the arm assembly in a manner such as to raise and lower the implement, a second ram arranged and operable to cause the reach of the arm assembly to be extended and retracted, an angling ram operable to rotate the implement relative to the arm for adjustment of the implement working attitude, and a compensation ram connected to a member movable by operation of one of the first and second rams, the compensation ram having a fluid outlet connection with the angling ram and being operable, in response to movement of said member, to cause fluid displacement in the angling ram in order to produce a compensatory change in attitude of said implement.

2. Apparatus according to Claim 1 wherein a further compensation ram is connected to a second member movable by operation of the other of the first and second rams, said further ram having a fluid outlet connection with the angling ram and being operable in response to movement of said second member to displace fluid into the angling ram in order to produce a compensatory change in the attitude of said implement additional or alternative to that produced by the compensation ram connected to said first member.

3. Apparatus according to Claim 1 or Claim 2 wherein the carrier is pivotally mounted on a relatively fixed support and forms one arm of a parallelogram linkage, of which the opposed arm is formed by a portion of said second arm projecting beyond its pivotal connection with said first arm, said linkage also including said first arm and a generally parallel linking arm extending between said projecting second arm portion and being pivoted on the carrier at a location spaced from the first arm pivot, said first ram and one compensation ram acting between the carrier and said fixed support and said second ram and further compensation ram acting between said first arm and the carrier.

4. Apparatus according to any one of the preceding claims wherein the angling ram is carried by the second arm.

5. Apparatus according to any one of the preceding claims wherein the angling ram is connected to the implement by way of an angling mechanism which comprises an arm fast for rotation with a shaft and pivotally mounting the implement, said other end of the ram being connected to said shaft by a slave link pivoted relative to the shaft and ram, the second arm being connected to the slave link by a radius arm connected between the second arm and the link, the arrangement being such that the radius of action of the ram is maintained substantially constant during relative pivotal movement between the implement and second arm.

6. Apparatus according to any one of the preceding claims wherein said one compensation ram and said first ram are pivotally connected to the carrier at respective positions at either side of the pivotal connection of the carrier with the fixed -support.

7. Apparatus according to any one of the preceding claims wherein said further compensation ram and said second ram are pivotally connected to the carrier at respective positions at either side of the pivotal connection of the first arm with the carrier.

8. Apparatus according to Claim 1, wherein the first and secpnd arms are in the form of a single jointed boom of which the inner part constitutes the first arm and is mounted on the fixed support, and the outer part constitutes the second arm and carries the implement, said first ram acting between the support and the inner part of the boom and said second ram between the first and second arms, said compensation rams being arranged for operation respectively by said first and second arms.

9. Apparatus according to any one of the preceding claims wherein each compensation ram and the angling ram are double-acting, enabling compensatory movement of the angling ram to take place in two opposed directions corresponding to the directions of movement of the or each arm.

10. Apparatus according to any one of the preceding claims, wherein either or both of the first and second arms is divided into two or more mutually pivotable parts actuated by a respective additional ram connected between each pair of parts, a further compensating ram acting between each such pair of parts and having a fluid outlet connection with the angling ram so as to effect compensatory movement of the latter upon pivotal movement between the associated pair of parts.

11. Apparatus according to Claim 10 wherein the first arm is a single arm adapted to be pivotally mounted on a support and the second arm comprises a pair of pivotally interconnected parts, one such part having its free end portion pivotally connected to the first arm and the other part having an implement mounted in the region of its free end.

12. Apparatus according to any one of the preceding claims wherein the or each compensation ram operates to displace fluid into the angling ram to produce said compensatory change in attitude of said implement.

13. Apparatus according to any one of the preceding claims wherein said fixed support is mounted on a towing vehicle.

14. A vegetation cutting apparatus substantially as hereinbefore described with reference to the accompanying drawings.