GB2278037A - Strut connector for a tractor - Google Patents

Abstract

A connector between a strut (6) (Figure 1) of a three-point attachment linkage (2) for an agricultural tractor (1) and an associated lower steering arm (3a) of the linkage comprises a yoke (16), an eye member (17) and a coupling pin (18). The coupling pin extends through co-axial cylindrical bores in spaced arms (20, 22) of the yoke and through a cylindrical bore in the eye member. The centre region of the coupling pin engaged in the cylindrical bore of the eye member is of spherical configuration permitting non-jamming articulation of the eye member relative to the coupling pin. The yoke (16) is provided at the outward end of the strut (6) and the eye member (17) is connected to the steering arm (3a). <IMAGE>

Description

Title: Strut Connector Description of Invention This invention relates to a connector between a strut, which may comprise a side strut or a side stabiliser, of a three-point attachment linkage for a tractor and an associated lower steering arm of a said linkage, comprising a yoke member and an eye member, one of said members being associated with the strut and the other of said members being associated with the lower steering arm, and a coupling pin extending through a bore in the yoke member and a bore in the eye member for pivotally connecting the eye member to the yoke member, a limited amount of free play being provided between the faces of the eye member and respective adjacent inner faces of the yoke member.

Such a connector is known from German utility model 6915230 published 21st August 1979. In this disclosure the coupling pin associated with the yoke is of cylindrical configuration whereas the eye member has a bore which increases in diameter from its centre towards each of its two ends. In this construction, the centre region of the bore requires a large amount of free play relative to the coupling pin in order to avoid any jamming. The production of such a bore of generally double conical configuration is expensive in view of the machining work which is involved.

Another connector is known from U.S.A. Patent 4862971 published 5th September 1989. In this disclosure, the inner end of the strut is secured to the rear end of the tractor by a ball joint. The pivot axis of the pin securing the ball joint extends horizontally as does the pivot axis of the pin which mounts the inner end of the lower steering arm to the rear end of the tractor. The axis of the coupling pin of the connector intersects the axis of the pin for securing the strut.

Because the lower steering arm is articulated to the rear end of the tractor by means of a ball joint, the arm is permitted to carry out spatial movements which, even though these are limited, may cause jamming in respect of the articulation of the strut even though the strut itself is connected to the rear end of the tractor by means of a ball joint.

It is an object of the present invention to provide a connector between a side strut or side stabiliser and the associated lower steering arm of a threepoint attachment linkage of a tractor which will overcome at least some of the jamming problems associated with known connectors.

In accordance with the invention there is provided a connector between a strut of a three-point attachment linkage for a tractor and an associated lower steering arm of a said linkage comprising a yoke member and an eye member, one of said members being associated with the strut and the other of said members being associated with the lower steering arm, and a coupling pin extending through a bore in the yoke member and a bore in the eye member for pivotally connecting the eye member to the yoke member, a limited amount of free play being provided between the faces of the eye member and respective adjacent inner faces of the yoke member wherein the outer face of the coupling pin which engages the bore in the eye member is convex and wherein the bore in the yoke member is of cylindrical configuration.

One advantage of the connector of the invention is that movement of the convex outer face of the coupling pin relative to the cylindrical bore of the eye member also permits spatial movements between the lower steering arm and the yoke member. In consequence, within the limits within which the lower steering arm is able to carry out pivot movements about its longitudinal axis, pivot movements are also permitted between the yoke member and the eye member of the connector. Therefore, it is not possible for any jamming to occur in respect of the parts connected to one another by the connector or in the connecting region, and as a result, any damage to the parts to be connected is avoided.

The connector of the invention eliminates the jamming problem costeffectively and, as a result of the convex shape of the coupling pin, only a small amount of play is required. Furthermore, the connector in accordance with the invention is more suitable for accommodating high forces than the prior art connectors in which the coupling pin has a cylindrical shape.

Preferably, the outer face of the coupling pin is of convex spherical configuration with the centre of the spherical region being centred on the longitudinal axis of the coupling pin. The diameter of the spherical face of the coupling pin corresponds to the diameter of those parts of the coupling pin which engage the bore in the yoke member. The cylindrical bore of the eye member enables the eye member to assume different spatial angular positions relative to said spherical outer face of the coupling pin.

The eye member may be attached to a said lower steering arm and the yoke member may be attached to a said strut or, alternatively, the eye member may be attached to a said strut and the yoke member may be attached to a said lower steering arm.

Other features of the invention will become apparent from the following description given herein solely by way of example with reference to the accompanying drawings wherein: Figure 1 is a somewhat diagrammatic top-plan view of the rear end of an agricultural tractor having a three-point attachment linkage wherein one lower steering arm thereof is connected to a strut by a connector in accordance with the invention; Figure 2 is a part sectional side view of the connector showing the strut and the lower steering arm; Figure 3 is a side view to an enlarged scale of the connector of Figure 2.

Figure 1 shows the rear end of a tractor 1 having a three-point attachment linkage 2 comprising two lower steering arms 3a, 3b attached to the rear of the tractor so as to be pivotable around the pivot points 4. Said lower steering arms 3a, 3b are attached to the tractor so as to be laterally spaced from the longitudinal axis of the tractor 1 on opposite sides of said axis. The rearward free ends of the lower steering arms 3a, 3b carry coupling hooks 5 for the reception of bearing assemblies such as coupling balls of an implement to be attached. One of the two lower steering arms, i.e. the lower steering arm 3a as illustrated, is supported on the rear end of the tractor 1 by means of a telescopic side strut 6. At a pivot point 8, an inner end of the side strut 6 is attached to the tractor 1 by means of a coupling pin with a substantially horizontally extending axis. The pivot point 8 permits the side strut 6 to pivot around said axis which is located on an extension of the axes of the two pivot points 4 of the lower steering arms 3a, 3b. The outer end of the side strut 6 is connected to the associated steering arm 3a by means of the connector 7 of the invention. The pivot axis of the connector 7 is offset by 90" relative to that of the pivot point 8 as a result of which the side strut 6 permits pivot movements of the lower steering arm 3a around the pivot point 4 upwardly, as well as lateral sway or pendulum movements of said arm.

The length of the side strut 6 is adjustable, but its degree of telescopic movement may be varied by a locking mechanism. However, telescoping of the side strut 6 may selectively be prevented whereby an implement attached to the three-point attachment linkage will be prevented from developing sway or pendulum movements. Only the lower steering arm, such as the arm 3a, requires a side strut 6 because the other lower steering arm 3b is maintained at a distance from the arm 3a by the implement itself. To brake any lateral floating when the arms are free to float, it is preferable to provide a resilient side stabiliser 12 which may be attached to the other lower steering arm 3b and tractor 1 in a similar manner to that in which the side strut 6 is attached. The purpose of the side stabiliser 12, however, is merely to set a preferred neutral position and to damp vibrations. From this neutral position, the stabiliser 12 permits resilient movement thereof.

The three-point attachment linkage also includes an upper steering arm 11 which is also pivotally attached to the rear end of the tractor 1 and which may be connected to an upper articulation point of an implement. Such implement would thus be guided by means of the lower steering arms 3a, 3b, the upper steering arm 11, the side strut 6 and the side stabiliser 12.

For preventing telescoping of the side strut 6, there is provided a locking ratchet which, by means of string biased tensile means 9 may be suspended from an attachment point 10 at the rear of the tractor. Although the tensile means 9 may be suspended from the attachment point 10, the spring arranged between the tensile means 9 and the locking ratchet permits relative movements of the side strut relative to the point 10, but, depending on the position of the lower steering arm 3a, it causes movement of the locking ratchet relative to the telescopic members of the side strut 6.

Figure 2 shows a side strut 6 and the manner in which it is associated with and articulated to the lower steering arm 3a by means of the connector 7 in accordance with the invention. Figure 3 shows the said connector to an enlarged scale.

For attachment to the pivot point 8 at the tractor 1, the side strut 6 is provided with a ball eye 13 comprising a ball joint permitting spatial movements of the side strut 6. The ball eye 13 is associated with the first telescopic part 14 of the strut 6 which, telescopically, accommodates the second telescopic part 15 along their common longitudinal axis.

At its outer free end, the second telescopic part 15 carries the connector 7. The connector 7 comprises a yoke member 16 which is either integral with the second telescopic part 15 or is firmly secured thereto. The yoke member 16 comprise a first or upper arm 20 and a second or lower arm 22 between which there is provided a relieved yoke region 30. The yoke region 30 accommodates an eye member 17 forming part of the connector 7 and which is pivotally connected to the yoke member 16 by means of a coupling pin 18 inserted into a cylindrical bore 19 extending through both yoke arms 20 and 22.

The coupling pin 18 also passes through a cylindrical bore 24 in the eye member 17. The coupling pin 18 is provided with a collar 21 by means of which it rests against the upper outer face of the first arm 20. The coupling pin end protruding below the lower outer face of the outer arm 22 has a diametric though bore into which is inserted a securing pin 23 for securing the pin 18 relative to the yoke member 16. Between the two outer side faces 26, 27 of the eye member 17 and the respective adjacent two inner faces 28, 29 of the arms 20, 22 of the yoke member 16, there is provided a certain amount of free play.

The design of the coupling pin 18 is shown in greater detail in Figure 3 from which it will be seen that the pin 18 has two cylindrical portions 36, 37, one of which, i.e. the cylindrical portion 36, engages the bore 19 of the first arm 20 of the yoke member 16, with the second cylindrical portion 37 being received in the bore 19 extending through the second arm 22. The region of the coupling pin between the two cylindrical portions, i.e. the portion of the outer face of the coupling pin 18 by means of which the coupling pin is accommodated in the cylindrical bore 24 of the member 17 is of spherical configuration. The outwardly convex spherical outer face providing said spherical configuration is referred to by reference number 15. The centre of the spherical outer face 35 is centred on the longitudinal axis 25 of the coupling pin 18. The outer diameter of the spherical outer face 35 substantially corresponds to the diameter of the two cylindrical portions 36, 37 of the coupling pin 18. By arranging for the spherical outer face to be received in the cylindrical bore 24, it is possible for the tensile eye member 17 to carry out spatial angular movements relative to the yoke member 16. In particular, an additional rotational degree of freedom in the direction of the two arrows (shown at the right-hand end of each of Figures 2 and 3) is provided for the lower steering arm 3a relative to the side strut 6.

The eye member 17 is provided with a collar 32 and an adjoining shank 31, an outer threaded shank part 33 of which is engaged in a bore 38 of the lower steering arm 3a extending transversely relative to its longitudinal axis. The collar 32 abuts the outer face of the lower steering arm 3a. The threaded shank part 33 projects out of the other side face of the lower steering arm 3a whereby the eye member 17 may be secured to the lower steering arm 3a by means of a nut 34 threaded on to the threaded shank part 33. The articulating ability of the lower steering arm 3a relative to the side strut 6 in the upward direction is indicated by dashed lines in Figure 2.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (7)

1. A connector between a strut of a three-point attachment linkage for a tractor and an associated lower steering arm of a said linkage comprising a yoke member and an eye member, one of said members being associated with the strut and the other of said members being associated with the lower steering arm, and a coupling pin extending through a bore in the yoke member and a bore in the eye member for pivotally connecting the eye member to the yoke member, a limited amount of free play being provided between the faces of the eye member and respective adjacent inner faces of the yoke member wherein the outer face of the coupling pin which engages the bore in the eye member is convex and wherein the bore in the yoke member is of cylindrical configuration.

2. A connector as claimed in Claim 1 wherein the outer face of the coupling pin is of convex spherical configuration.

3. A connector as claimed in either one of Claims 1 or 2 wherein the eye member is attached to said lower steering arm and the yoke member is attached to said strut.

4. A connector as claimed in either one of Claims 1 or 2 wherein the eye member is attached to said strut and the yoke member is attached to said lower steering arm.

5. A connector between a strut of a three-point attachment linkage for a tractor and an associated lower steering arm of a said linkage constructed and arranged substantially as hereinbefore described with reference to any one of the accompanying drawings.

6. A strut connectable between a lower steering arm of a three-point attachment linkage for a tractor, and the tractor itself, incorporating a connector as claimed in any one of the preceding Claims.

7. Any novel feature or novel combination of features hereinbefore described and/or shown in the accompanying drawings.