GB2194423A - Vegetation cutting apparatus - Google Patents

Abstract

A vegetation cutting apparatus has a main support (3) mountable on a vehicle (2) and having a boom (4) pivoted thereon and carrying an implement (10). A ram (6) is pivotally mounted on the support (3) and arranged to pivot the carrier in a vertical plane from one side of the vehicle to the other. The main support carries a pair of swinging links (19) each mounted on the vehicle by way of a respective swivel joint (17), the links being pivoted on the main support (3) at points on the links below said joints (17). Locking means (23) is provided selectively to lock the links to the support enabling an upward break-back action of the carrier to occur about the swivel joint (17) associated with the locked link remote from the implement. <IMAGE>

Description

GB2194423A 1 SPECIFICATION cally upon encountering an obstruction so as to

minimise the risk of damage to the imple Vegetation cutting apparatus ment. Preferably, the carrier returns to its ini tial position under the effect of gravity, al This invention relates to vegetation cutting 70 though spring or fluid pressure assistance, for apparatus which includes an implement carrier example, may be provided as desired.

mountable on a carrying vehicle and pivotable, Conveniently, the locking means is actuated in use, about a generally horizontal axis, usu- by said power means to lock the main sup ally extending fore and aft of the vehicle to port to one or other of said links depending permit the implement to cut vegetation at 75 upon the position assumed by the boom.

either side of the vehicle. The implement is preferably driven by a fluid It is a common occurrence during cutting motor and the supply to fluid under pressure operations with apparatus of this general kind to the motor is then conveniently controlled for the implement to encounter an obstruction, by a control valve comprising a first spool such as an extra thick branch in the case of a 80 having a neutral position providing an open hedge cutter for example, or a boulder or tree centre path between a fluid pressure inlet and stump in the case of a mower. Collision " with the motor, and an operative position in which such an obstruction can cause serious damage fluid from said inlet is supplied to a double to the implement and it is therefore necessary acting device, the fluid discharge from which to incorporate some form of -break-back- 85 is returned to an alternative fluid supply path mechanism to enable the implement to ride established by the spool between said device over the obstruction and to resume its normal and the motor. The valve preferably also in cutting attitude once the obstruction has been cludes an additional spool operable to divert cleared. Various mechanical and fluid-operated fluid flow from the motor when no drive is arrangements have been proposed for this 90 required.

purpose and, whilst generally satisfactory, The invention will now be described, by these have tended to be complicated and ex- way of example, with reference to the accom pensive. panying drawings in which:

An object of the present invention is to pro- Figure 1 is a diagrammatic view from the vide a vegetation cutting apparatus incorporat- 95 rear of one form of the cutting apparatus of ing an effective break-back mechanism of rela- the invention mounted on a vehicle and shown tively simple and inexpensive construction. in alternative positions of use; According to the invention, vegetation cut- Figure 2 is an enlarged view from the side ting apparatus comprises a main support hav- of part of the arrangement of Figure 1; ing means for mounting it on the vehicle, an 100 Figure 3 is a view to a further enlarged implement carrier adapted for the mounting of scale of part of the apparatus as illustrated in an implement thereon and pivotally carried by Figure 2 shown in alternative positions of use; the main support, power means for pivoting Figure 4 illustrates a form of locking device the carrier in a generally vertical plane be- incorporated in the apparatus of Figure 1 to 3; tween two operative positions in which it ex- 105 Figures 5A to 5C illustrate an angling tends laterally from either side respectively of mechanism associated with pivotally intercon the main support, said main support mounting nected parts of the apparatus, and means including a pair of transversely spaced Figure 6 is a diagrammatic representation of swinging links each of which is mounted, in a hydraulic circuit for controlling operation of use, on a respective swivel joint connected to 110 the apparatus of the invention.

the vehicle, said links being also pivotally con- Referring to the drawings, Figure 1 illus- nected at points thereon below the joints to trates a cutting apparatus, indicated generally the main support, and locking means operable at 1, in the form of a hedge cutter mounted selectively to lock together the main support on the rear of a vehicle, such as a tractor, and that link at the side of the main support 115 indicated generally at 2. The cutting apparatus remote from the implement, the arrangement includes a main support 3 in the form of a being such that, with the main support generally triangular frame mounted on the trac mounted on the vehicle, movement of the tor, the frame carrying a boom 4 pivoted at 5 implement carrier and support rearwardly of to an upper location on the frame. Power the vehicle away from the cutting location 120 means, in the form of a ram 6 is pivotally causes the support to pivot about an inclined connected at 7 to the frame 3 and at 8 to the axis passing through the swivel joint associ- boom 4 and is operable to swing the boom ated with the locked link so as to induce lift- about its pivotal connection 5 with the frame ing movement of the support and carrier so that the boom may assume alternative op against a force tending to return them to their 125 erative positions respectively at either side of initial position, said lifting movement being ac- the tractor. An extreme pivotal position A, in commodated by the unlocked link and associ- which the boom is angled downwardly, is il ated swivel joint. lustrated in broken lines at the left-hand side The arrangement of the invention thereby of Figure 1 and the boom may be swung from enables the implement to be raised automati- 130 this position to a similar one at the right-hand 2 GB2194423A 2 side of the tractor. The boom carries, at its event of misalignment.

free end, a cutting head 10, illustrated as a Actuation of the locking mechanism is ef- bar cutter, which is pivotally mounted on the fected by pivotal movement of the ram 6 boom and can be swung through an are of about its connection 7 with the frame, during approximately 250' by a ram 11 which actu- 70 which movement the ram moves between re ates the arm through an angling mechanism spective over-centre positions relative to the 12 to be described in more detail hereafter. line joining the pivots 5 and 7. The lower end The means for mounting the frame 3 on the of the ram is provided with a rigid depending tractor are illustrated in more detail in Figures tongue 30, the free end of which extends be 2 to 4. The implement is carried by the upper 75 tween the collars 26. It will be seen that, as and lower links 13, 14 of a conventional trac- the ram 6 assumes an over- centre position at tor three point linkage, the upper link 13 being one side or the other relative to the frame 3, pivotally connected directly to a lug 15 on the the tongue will abut one or other of the col implement by way of a swivel joint 13A. The lars 26 and urge the locking bar into engage lower links 14, which are spaced transversely 80 ment with the holes 24, 25 at one side of the of the tractor but of which only one is visible frame, thereby locking the swing link 19 and in the drawings, are interconnected by a lug 20 rigidly together at that side of the mounting bar 16 which is threaded through frame. This is essential in order to enable the respective swivel joints 17 carried by the link 19 on the side of the vehicle remote from outer ends of the lower links 14. The mount- 85 the direction of lateral extension of the boom ing bar 16 is braced vertically by a pair of to pivot correctly about the swivel joint 17 upwardly convergent arms 18, only-one of during break-back of the implement, as will which is visible in the drawings, the top ends now be described.

of which are connected to the tractor top For a given cutting operation, the boom 4 is hitch position H to which the arm 13 is also 90 pivoted about the connection 5 by actuation connected, the other ends of the arms 18 of the ram 6 to a position in which it extends being connected to locations respectively to- laterally to one side or the other of the tractor wards the outer ends of the bar 16, thereby longitudinal axis, according to the cutting op forming a bracing triangulated yoke assembly. eration to be performed. During its boom-actu The implement 1 is slung on the bar 16 by 95 ating operation, the ram 6 pivots about its way of a pair of swing links 19 which are connection 7 with the frame and automatically mounted at their respective upper ends on the causes the tongue 30 to move the locking bar swivel joints 17, the implement being pro- 23 into one of its locking positions. For the vided with respective Jugs 20, each compris- boom disposition illustrated in full lines in Fig ing. a pair of spaced parallel plates 21 which 100 ure 1, the locking bar 23 will have been embrace the adjacent swing link 19 and are moved to the left into engagement with the pivotally connected to the lower end thereof holes in the left-hand link 19 and lug 21, by a pin 22. thereby to render the lug and link relatively For reasons which will become apparent rigid so that the frame 3 can pivot about the hereafter, it is necessary to lock one or other 105 swivel joint 17 by way of the swing link 19.

of the swing links 19 to the associated lug 20 The weight and balance of the frame 3 is of the implement, according to the attitude such that rearward forces arising on the frame adopted by the implement laterally of the as a result of normal cutting action of the vehicle. For this purpose, the implement is cutter bar 10 during forward movement of the provided with a locking bar 23 (Figure 4) car- 110 tractor will not dislodge the frame significantly ried by the frame 3 in slidably reciprocable in a rearward direction. However, in the event manner and concentrically aligned with holes that the cutter bar encounters an obstruction, 24 and 25 formed respectively in the swing such as, for example, a heavy branch which it links 19 and one of the lug plates 21. The bar is incapable of cutting, continued forward carries a pair of collars 26 at a central loca115 movement of the tractor causes the arm to tion thereof, the collars being slidable relative move rearwardly relative to the tractor, pivot to the bar 23 but urged towards one another ing about the line P-P (Figure 1) passing by respective springs 27 acting between the through the swivel joint 17 on the opposite respective outer ends of the collars 26 and side of the tractor and the swivel joint 13A washers or similar means 28 anchored on the 120 between the frame and the upper connecting bar. The strength of the springs 27 is such as arm 13. The tilting attitude of this pivotal axis to transmit actuating force applied to the bar, means that rearward movement of the frame in the manner to be described, in order to is necessarily accompanied by a lifting move move the bar in translation and engage it ment of the arm side of the frame, this move within the holes 24, 25, but to yield in the 125 ment being accommodated by the pivot 22 event that the bar is obstructed from engaging between the link and lug 20 at the arm side both of the holes 24, 25 due, for example, to of the tractor which are not locked together, misalignment of the latter. This yielding ar- and the swivel joint 17. The degree of raising rangement ensures that untoward strain is not of the swing link 19 and therefore of the sustained by the locking mechanism in the 130 implement frame 3 is illustrated in Figure 3 by 3 GB2194423A 3 showing the position in broken lines of the tor M which drives the cutter bar to perform a link 19 at the maximum break-back position of cutting operation, as well as supplying alterna the frame. Such lifting of the implement frame tive services illustrated as double-acting rams will enable the cutter bar to clear most ob- R' and W. The valve assembly includes three stacles normally encountered during a cutting 70 spools S', S", S each capable of adopting operation. A similar break-back action occurs one of three positions and forming a conven with the arm disposed in any of the alterna- tional open centre valve such that, with the tive positions A, B, or C, illustrated in the spools in their neutral positions as shown, drawings, or any intermediate position. Once fluid pressure input derived from a pump on the obstacle has been cleared, the frame and 75 the tractor will pass straight through the valve implement may return under gravity to the assembly along line L, to power the motor M.

normal cutting position, although it would be When it is desired to operate, for example, possible to provide spring or fluid pressure the ram R', movement of the spool S' from assistance for the return movement, if re- the illustrated neutral position to its downward quired. 80 operative position, as viewed in the drawing, Figures 5A to 5C illustrate an angling blocks off the centre path and permits fluid to mechanism which connects the ram 11 to the be supplied from the input to the left-hand cutter bar 10 and enables the ram to pivot side of the ram R' via line L2. Oil discharged the cutter bar through a substantial arc whilst from the right-hand side of the ram will be maintaining a more or less uniform speed of 85 returned via line L, to a by-pass line L, which rotational movement of the bar. The cutter bar is connected to the line L, at the motor side is mounted on the boom portion 413 by of the control valve so that the discharged oil means of a shaft 40 which also has an arm is used to power the motor. A similar action 41 fast for rotation with the shaft and with occurs when the spool S' is moved to its the cutter bar. The piston rod 11 A of the ram 90 uppermost operative position, the ram then 11 is connected to the arm 41 by a slave link being operated in the reverse manner. The 42 which is pivotally connected at its respec- valve W operates the ram W in a similar man tive ends. to the piston rod and arm. The ner. The spool S is provided to enable the slave link is connected in turn to the boom by motor to be switched on and off and it will a curved radius arm 43 pivoted to the boom 95 be seen that with this spool in its upward and to the link 42, the pivotal connection with operative position (as seen in the drawing), the latter being at an intermediate location the pressure input from the tractor is diverted thereon spaced from the respective connec- via line 4 and a return path through the spool tions with the piston rod and arm 41. Figure S into line L5 and thence into the main return 5A illustrates the mechanism in its retracted 100 line L, from the motor to tank in such a man position with the cutter bar 10 laid back over ner as to by-pass the motor. Although Figure the boom portion 4B. In Figure 513, the 6 illustrates two rams R' and W and corre mechanism is in an intermediate position with sponding spools S' and W, it will be under the cutter bar 10 having been moved through stood that any number of rams and spools approximately 900 to an upright position. Fig- 105 may be employed, being connected into the ure 5C illustrates the fully extended position of circuit in the manner of those illustrated.

the mechanism in which the cutter bar has The supply of oil to the rams is restricted in been pivoted through approximately 250'. The order to ensure that this supply is always less curvature of the radius arm is chosen so that, than the total oil flow at the normal working in the fully extended position of Figure 5C, the 110 speed of the motor so that there is always radius arm may embrace the adjacent end of some oil supply to the motor even when both the link 41 thereby contributing to the large of the rams R', W, are in operation. This may angular sweep of which the arm is capable. result in a temporary but acceptable slight re The positions of the various pivotal connec- duction in motor speed during operation of tions between the arms 41, 42 and 43, to- 115 one or both of the rams. It will be seen that gether with the lengths of the arms are cho- the valve assembly described enables the mo sen such that the radius of action of the slave tor to be supplied from the main tractor pres link 42, and thus of the pivotal connection of sure input without having recourse to the con the rod 11 A with the link 42, remains sub- ventional expensive practice of providing a se stantially constant throughout the full rotational 120 parate pump to drive the motor independently movement of the cutter bar, which means that of the other services.

the speed of rotation of the cutter arm and

Claims (1)

1. actuating force applied by the ram also re- CLAIMS mains substantially

   uniform. In particular, the 1. Vegetation cutting apparatus comprising a separation of the radius arm and piston rod 125 main support having means for mounting it on pivot locations on the slave link makes a sig- the vehicle, an implement carrier adapted for nificant contribution to the advantageous geo- the mounting of an implement thereon and metry of the arrangement. pivotally carried by the main support, power Figure 7 illustrates a control valve operable means for pivoting the carrier in a generally to control the supply of motive fluid to a mo- 130 vertical plane between two operative positions 4 GB2194423A 4 in which it extends laterally from either side tween the parts.

   respectively of the main support, said main 8. Apparatus according to Claim 7 wherein support mounting means including a pair of the radius arm is arcuate and arranged to em transversely spaced swinging links each of brace said pivotal connection when the imple- which is mounted, in use, on a respective 70 ment assumes an extreme outwardly extended swivel joint connected to the vehicle, said position.

   links being also pivotally connected at points 9. Apparatus according to any one of the thereon below the joints to the main support, preceding claims wherein the implement is and locking means operable selectively to lock driven by a fluid motor and the supply of fluid together the main support and that link at the 75 under pressure to the motor is controlled by a side of the main support remote from the control valve comprising a first spool having a implement, the arrangement being such that, neutral position providing an open-centre path with the main support mounted on the vehicle, between a fluid pressure inlet and the motor, movement of the implement carrier and sup- and an operative position in which fluid from port rearwardly of the vehicle away from the 80 said inlet is supplied to a double-acting device, cutting location causes the support to pivot the fluid discharge from which is returned to about an inclined axis passing through the an alternative fluid supply path established by swivel joint associated with the locked link so the spool between said device and the motor.

   as to induce lifting movement of the support 10. Apparatus according to Claim 9 wherein and carrier against a force tending to return 85 the valve includes an additional spool operable them to their initial position, said lifting move- to divert fluid flow from the motor when no ment being accommodated by the unlocked drive is required.

   link and associated swivel joint. 11. Vegetation cutting apparatus substan- 2. Apparatus according to Claim 1 wherein tially as hereinbefore described with reference the carrier is gravity-urged, with or without 90 to the accompanying drawings.

   spring or fluid pressure assistance, towards its initial position. Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from - 3. Apparatus according to Claim 1 or Claim The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BF15 3RD.

   2 wherein the locking means is actuated by Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.

   the power means to lock the main support to one or other of said links depending upon the position assumed by the boom.

   4. Apparatus according to Claim 3 wherein the locking means includes a rod translation ally movable by the power means to engage one or other of said links and an adjacent part of said main support in order to lock said engaged link to the support.

   5. Apparatus according to Claim 3 wherein said- power means applies locking force to the rod via yieldable means which absorbs the force in the event that engagement of the rod and support part is obstructed.

   6. Apparatus according to Claim 4 or Claim 5- wherein the power means moves angularly during pivoting of the carrier between its two operative positions, the power means being coupled to the rod in such a manner that said angular movement produces said translational movement of the rod.

   7. Apparatus according to any one of the preceding claims wherein the implement carrier is a boom having an implement pivotally mounted adjacent one end thereof, a fluid pressure-operated device fixed relative to the boom, a slave link connected between said device and a location on the implement spaced from the implement pivotal mounting location, and a radius arm connected between the boom and an intermediate location on the slave link between the connections of that link with said device and the implement, the ar rangement being such that the radius of action of said device is maintained substantially Con stant during relative pivotal movement be-