GB2281495A - Vehicle linkage - Google Patents

Abstract

A linkage (12) for coupling a vehicle (10) to a ground-engaging implement (11) comprises a first link (14) which is joined to the vehicle by means of a multidirectional joint (19) and to the implement by means of a unidirectional joint (15) and a second link (13) which is joined by a unidirectional joint (15) to the vehicle and by a multidirectional joint (19) to the implement. The linkage allows the implement to tilt transversely and reduces the tendency of the implement to sway when carried. <IMAGE>

Description

Vehicle Linkage The present invention concerns a linkage for coupling vehicles to ground-engaging implements, for example for coupling a wheeled vehicle to a snow-plough or to agricultural machinery.

Such couplings are well-known, an example being the so called "three-point linkage" which has thee pivotting linkages which can pivot up and down to allow the coupled implement to ride over bumps etc.

in the ground and a fourth linkage for lifting the implement clear of the ground for transportation.

Although such linkages do allow the implement to pivot upwardly to accommodate uneven ground, they cannot allow the implement to tilt so that one side of the implement is lower than the other.

Such tilting action is desirable to keep the implement close to the ground when the ground is higher on one side of the implement than on the other. A further disadvantage of these linkages is that, especially when being carried above the ground, they allow the implement to sway from side to side, which is undesirable and can be dangerous.

It is an object of the present invention to provide a linkage which overcomes some, at least, of these problems.

According to the invention, a linkage for coupling a vehicle to a ground-engaging implement comprises a first link joined at one end to the vehicle in such a way as to allow pivotal movement between the vehicle and said first link both around a longitudinal axis of said first link and around a line transverse to said longitudinal axis and joined at the other end to the ground-engaging implement in such a way as to allow pivotal movement between the implement and said first link around a line transverse to said longitudinal axis of the link; and a second link joined at one end to the vehicle in such a way as to allow pivotal movement between the vehicle and said second link around a line transverse to a longitudinal axis of said second link and joined at the other end to the implement in such a way as to allow pivotal movement between the implement and said second link around saidlongitudinal axis of said second link and also around a line transverse to said longitudinal axis of said second link.

The first and second links may each comprise an elongate bar or may be T-shaped, triangular, rectangular, or otherwise shaped when viewed in plan.

The surfaces of the links may form a continuous plane or they may comprise a framework. The longitudinal axis of each link is aligned with the longitudinal axes of the vehicle and the implement. The first and second links are preferably disposed one above the other and spaced apart vertically. The first and second links are preferably of a similar shape and size.

The joints which join the first link to the implement and the second link to the vehicle (hereinafter referred to as "unidirectional joints") allow a pivotal motion between the respective link and the park joined thereto around a line transverse to a longitudinal axis of the respective link. A suitable joint for this purpose is a simple pinned pivot or hinge, preferably in the form of a so-called clevis joint.

The joints which join the first link to the vehicle and the second link to the implement (hereinafter referred to as "multi-directional joints") allow a pivotal motion between the respective link and the part joined thereto both around a longitudinal axis of the respective link and around a line transverse to that longitudinal axis. Those joints may comprise a combination of simple pivots or a specially-shaped pin pivot which can allow some pivotal movement both around the axis of the pin and in another direction. More preferably however, that joint will comprise a pinned ball joint.

It is advantageous for the unidirectional joint to form a connection between a link and the vehicle or implement over a relatively large proportion of the width of the connected parts to improve the stability of the linkage and, in particular, to restrain the tendency of the implement to sway or swing around a vertical axis relative to the vehicle. For example, the unidirectional joint may take the -form of an elongate hinged connection extending up to the entire width of the vehicle, implement or link. Alternatively a plurality of shorter unidirectional joints may be provided spaced along the join. In a preferred form of the invention in which the end of each link which is to be joined unidirectionally is of a comparable width to that of the vehicle or implement to which it is to be joined, a unidirectional pivot joint is provided at or near each side of the link. More preferably two unidirectional joints are provided, one at each side of the link which, together with a single multidirectional joint at the other end of the link define the corners of an isosceles triangle when viewed in plan, the multi-directional joint forming the apex of said triangle. Most preferably each link comprises an isosceles triangle having a joining point at or near each corner, the links being arranged vertically spaced one above the other with the apex of the respective triangles pointing in opposite directions.

The linkage according to the invention allows the attached implement to follow the contours of the ground by virtue of the joints allowing the implement to pivot up and down and also to twist around a longitudinal axis so that one side of the implement may be higher than the other. The use of such a linkage ensures that the implement remains essentially parallel to the vehicle so that its direction can be readily controlled and swaying of the implement during transport is prevented.

The provision of the second link provides vertical support to the implement to prevent it from 'nose-diving' Optionally, a lifting device may be provided to raise and lower the implement out of and into engagement with the ground. A preferred form of device for this purpose comprises a hydraulically operated piston mounted upon the implement and adapted to push downwardly upon a part of the linkage in order to raise the implement.

Restraining devices such as chains may be provided between the two links to restrict their relative movement in order to prevent the implement from twisting beyond a certain point.

A preferred embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawing, which is a perspective view of a linkage according to the invention used to couple a truck to a snow-plough.

The drawing depicts a truck 10 coupled to a snowplough 11 by means of a linkage 12 according to the invention. The linkage comprises two triangular steel links 13, 14 connected at each corner to either the truck or the snow-plough. The joints 15 are clevis joints forming unidirectional pivots around the pin of each joint. The two joints 16 comprise ball joints each having a ball 17 partially surrounded by a part of the link 19 and a pin 18 extending transversely through the ball 17 and the upstanding sides of the clevis 23.

Thus the ball joint joining the link 13 to the snowplough 12 provides pivotal motion around a generally longitudinal axis of the link 13 and around a line transverse to that axis by means of the part 19 of the link 13 moving around the ball 17. The ball joint at the apex of link 14 operates in a similar fashion.

A hydraulic cylinder 22 is mounted within the two upstanding sides of the clevis 23 and operates a piston 24 pivotally joined to a cross-member 25 of link 14. Activation of the hydraulic cylinder to push the link 14 downwards serves to raise the snow-plough relative to the truck.

Claims (18)

1. A linkage for coupling a vehicle to a groundengaging implement comprising a first link joined at one end to the vehicle in such a way as to allow pivotal movement between the vehicle and said first link both around a longitudinal axis of said first link and around a line transverse to said longitudinal axis and joined at the other end to the ground-engaging implement in such a way as to allow pivotal movement between the implement and said first link around a line transverse to said longitudinal axis of the link; and a second link joined at one end to the vehicle in such a way as to allow pivotal movement between the vehicle and said second link around a line transverse to a longitudinal axis of said second link and joined at the other end to the implement in such a way as to allow pivotal movement between the implement and said second link around said longitudinal axis of said second link and also around a line transverse to said longitudinal axis of said second link.

2. A linkage as claimed in claim 1, wherein said first and second links each comprise an elongate bar, or a T-shaped, triangular or rectangular shaped link, when viewed in plan.

3. A linkage as claimed in either claim 1 or claim 2, wherein the surfaces of the links form a continuous plane.

4. A linkage as claimed in either claim 1 or claim 2, wherein the links comprise a framework.

5. A linkage as claimed in any of the preceding claims, wherein said first and second links are of a similar shape and size.

6. A linkage as claimed in any of the preceding claims, wherein said first and second links are disposed one above the other and spaced apart vertically.

7. A linkage as claimed in any of the preceding claims, wherein the joint between said first link and said vehicle or between said second link and said implement (a multidirectional joint) is a combination of simple pivots.

8. A linkage as claimed in any of claims 1-6, wherein the joint between said first link and said vehicle or between said second link and said implement is a pin pivot which can allow some pivotal movement both around the axis of the pivot and in another direction.

9. A linkage as claimed in any of claims 1-6, wherein the joint between said first link and said vehicle or between said second link and said implement is a pinned ball joint.

10. A linkage as claimed in any of the preceding claims, wherein the joint between said first link and said implement or between said second link and said vehicle (a unidirectional joint) is a clevis joint.

11. A linkage as claimed in any of the preceding claims, wherein the joint between said first link and said implement or between said second link and said vehicle is an elongate hinged connection which extends for up to the entire width of the vehicle, implement or link.

12. A linkage as claimed in any of claims 1-10, wherein the joint between said first link and said implement or between said second link and said vehicle comprises a plurality of unidirectional joints spaced apart along the join.

13. A linkage as claimed in claim 12 wherein two unidirectional joints are provided, one at each side of an end of a link which, together with a single multidirectional joint at the other end of said link, define the corners of an isosceles triangle when viewed in plan.

14. A linkage as claimed in claim 13, wherein each link comprises an isosceles triangle having a joining point at or near each corner, the links being arranged vertically spaced one above the other with the apex of the respective triangles pointing in opposite directions.

15. A linkage as claimed in any of the preceding claims further comprising a lifting device to raise and lower the implement out of and into engagement with the ground.

16. A linkage as claimed in claim 15, wherein said lifting device comprises a hydraulically operated piston mounted upon the implement and adapted to push downwardly upon a part of the linkage in order to raise the implement.

17. A linkage as claimed in any of the preceding claims, wherein restraining devices, such as chains, are provided between the two links to restrict their movement relative to one another.

18. A linkage, substantially as hereinbefore described, with reference to and as shown in the accompanying drawing.