GB2103064A

GB2103064A - Stabilizing device for tractor three point linkage

Info

Publication number: GB2103064A
Application number: GB08222460A
Authority: GB
Inventors: Patrick Mccormick
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-08-04
Filing date: 1982-08-04
Publication date: 1983-02-16
Also published as: IE51703B1; IE811771L; GB2103064B

Abstract

A telescopic stabilizing device for use with the three point linkage of an agricultural tractor comprises an elongate sleeve 10, a shaft 50 telescopically slidable relatively to the sleeve 10 and a screw threaded shank 60 engaging the other end of the sleeve. Four holes 22 are provided on the sleeve 10 and five holes are provided on the shaft 50 at a different pitch to the holes 22 allowing a vernier type variation in the effective overall secured length of the device. When the pin 70 is withdrawn from engagement with one of the holes 22 and 52, the sleeve 10 may be rotated with respect to the shank 60 to adjust the effective minimum unsecured length of the stabilizing device or to adjust the effective overall secured length of the device prior to reinsertion of the pin 70 in a hole 22 and an aligned hole 52. <IMAGE>

Description

SPECIFICATION Stabilizing devices for the three point linkage of agricultural tractors The present invention relates to stabilizing devices for the three point linkage of agricultural tractors.

The three point linkage is positioned at the rear of a tractor and comprises two draft arms and a top link arm positioned above and centrally between the two draft arms. The two draft arms which may be raised and lowered hydraulically, are attached to the chassis of the tractor in such a manner as to allow lateral movement of the draft arms. Many farm implements are attached to a tractor by means of the three point linkage mechanism, with some implements requiring the ability to move laterally or "swing" behind a tractor while other implements require to be held rigidly in position. Stabilizing devices are used to prevent or limit such lateral movement.

A stabilizing device is attached to a draft arm and to a point underneath the tractor. Normally, a stabilizing device is provided on each draft arm.

The following are examples of stabilizing devices which have been used hitherto: (1 ) a solid stabilizing bar, (2) a check chain comprising a chain and a turnbuckle which may be used to continuously vary the length of the check chain and (3) a telescopic stabilizer comprising a solid shaft which telescopes relatively to a sleeve; a number of holes are provided in the sleeve and the shaft and in order to fix the effective overall length of the stabilizer so as to prevent lateral movement, a pin is inserted through a hole in the sleeve and an aligned hole in the shaft.

Such known stabilizing devices have a number of problems. A stabilizing bar is fixed in length and so when implements having different distances between:he attachment means are used on a tractor, a shorter or longer stabilizing bar must be used. As the screw threads of a check chain must be positioned close to ground level to allow the turnbuckle to be manipulated easily, the screw threads may become caked in mud and the like causing the screw threads eventually to rust. The length of the telescopic stabilizer can only be varied by effecting coarse adjustments to the effective overall secured length of the stabilizer.

One object of the invention is to provide a telescopic stabilizing device whose effective overall secured length may be varied by effecting fine adjustments. It is also an object of the invention to prov;de a telescopic stabilizing device whose effective minimum unsecured length may also be varied by effecting fine adjustments. By the term "fine adjustment" is meant an adjustment in length by a definite discrete amount which is significantly smaller than the coarse adjustment which it is possible to effect on known telescopic stabilizing devices.

The present invention provides a telescopic stabilizing device for use with the three point linkage of an agricultural tractor, comprising an elongate sleeve, a shaft telescopically slidable relatively to the sleeve, means for securing the sleeve and shaft relatively to one another to define the effective overall secured length of the stabilizing device, means for effecting fine adjustment of the effective overall secured length of the stabilizing device, and attachment means for mounting the stabilizing device between a draft arm and the chassis of an agricultural tractor.

Advantageously, the sleeve and shaft each have a plurality of cooperating holes spaced apart in a direction parallel to the longitudinal axis of the stabilizing device, the holes being adapted to receive a securing pin, and the holes in the shaft being at a different pitch to the holes in the sleeve so as to allow for vernier type variation in the effective overall secured length of the stabilizing device.

The means for effecting fine adjustment may comprise or further comprise a screw-threaded shank engaging screw threading at the end of the sleeve remote from the shaft, said shank also providing a means for adjusting the effective minimum unsecured length of the stabilizing device.

Conveniently, a vibration counterweight is attached to the sleeve. The vibration counterweight may be in the form of a handle which may be used to rotate the sleeve relatively to the screw threaded shank.

The attachment means for mounting the stabilizing device to the chassis of an agricultural tractor is preferably provided on the screwthreaded shank.

Advantageously, a pin for engaging a hole in the sleeve and the shaft is attached permanently to the sleeve. The shaft is preferably solid, although a hollow shaft may also be used.

The invention will now be more particularly described with reference to the accompanying drawings, which show by way of example only, a preferred embodiment of a stabilizing device according to the invention.

In the drawings: Figure 1 is a perspective view of the stabilizing device; Figure 2 is an exploded plan view of the stabilizing device: Figure 3 is an exploded side view of the stabilizing device; and Figure 4 is an exploded underneath plan view of the stabilizing device.

Referring to the drawings, the stabilizing device comprises an elongate sleeve 10 having a larger diameter portion 20 at one end and an internally screw-threaded neck 30 at the other end with a shaft 50 engaging the portion 20 and a screw threaded shank 60 engaging the neck 30.

Four through-holes 22 are provided in the portion 20 at a pitch of one inch (25.4 mm). The shaft 50 is provided with five through-holes 52, equal in diameter to the holes 22, at a pitch of three quarters of an inch (19.0 mm). The shaft 50 is telescopically movable relatively to the sleeve 10 and may be secured with respect to the sleeve by inserting a pin 70 through a hole 22 and an aligned hole 52. Due to the difference between the pitches of the holes 22 and the holes 52 a vernier type variation in the effective overall secured length of the stabilizing device may be achieved by effecting fine adjustments of one quarter of an inch (6.4 mm). By using the combination of the four holes 22 and the five holes 52, any one of sixteen different effective overall secured lengths may be selected.

At the end 54 of the shaft 50 is a shoulder 56 which acts as a stop against the sleeve 10. A swivel end 58 is fixed to the end 54 to allow the stabilizing device to be connected to the draft arm of a tractor (not shown) using a nut 80, bolt 82 and contact plate 84. The end 62 of the shank 60 is provided with a swivel end 64 which with nut 80 and bolt 82 is used to connect the stabilizing device to a bracket (not shown) mounted on the chassis of the tractor.

When it is desired to allow an implement to move laterally or swing behind a tractor, the pins 70 of the two stabilizing devices used on a tractor are withdrawn to allow telescopic movement of the shaft 50 relatively to the sleeve 10 on each device. As the distance between the two draft arms is fixed by virtue of the draft arms being secured to the implement, the implement can move laterally, for example, to the left until the shoulder 56 contacts the sleeve 10 of the left hand stabilizing device. The implement can likewise move to the right until the shoulder 56 contacts the sleeve 10 of the right-hand stabilizing device. Attached to the sleeve 10 is a vibration counterweight 12 which prevents the sleeve 10 rotating with respect to the shank 60 and thus unthreading. As shown in Figures 1 and 3 the counterweight 12 is in a downwardly depending position.The counterweight 1 2 also functions as a handle which may be used to rotate the sleeve 10 at least through 360 degrees with respect to the shank 60 so as to move the sleeve 10 towards or away from the implement to vary the length of the lateral travel of the implement. The length of the lateral travel of the implement is determined by the effective minimum unsecured length of the stabilizing device, i.e. when the shoulder 56 is in contract with the sleeve 10. As the effective minimum unsecured length may be adjusted using a screw thread the steps of fine adjustment which it is possible to obtain depend on the pitch of the thread.Rotating the sleeve 10 with respect of the shank 60 may also be used to increase or decrease the effective overall secured length of the stabilizing device prior to the pin 20 being inserted through a hole 22 and an aligned hole 52, in which case the sleeve need only be rotated in steps of 1 80 degrees.

To prevent the pin 70 from being mislaid, a chain 86 is attached between the head of the pin and a U-shaped anchoring element 88 fixed to the sleeve 10. The anchoring element 88 is large enough to accommodate the pin between the legs of the U. A hole 90 in the end of the pin 70 can accommodate an R-clip (not shown) which may be used to hold the pin 70 in position when it is received in a hole 22 and hole 52 or between the legs of the U-shaped anchoring element 88.

As seen in Figure 4, a hole 14 is provided in the sleeve 10 adjacent the neck 30. The hole 14 allows access to the thread of the shank 60 so that the thread may be damaged on assembly of the stabilizing device, to prevent withdrawal of the shank 60 from the sleeve 10 during use of the stabilizing device. After assembly of the stabilizing device, a grease nipple (not shown) may then be inserted into the hole 14 to allow the thread of the shank 60 to be lubricated.

Because the shank 60 is positioned at a point clear of the ground, adjacent the rear axle of the tractor, the exposed screw threads of the shank do not collect as much mud and the like thrown up by the wheels of the tractor as the screw threads of the check chain as used hitherto.

In an alternative embodiment of a stabilizing device according to the invention (not shown in the drawings) the portion of the sleeve 10 remote from the larger diameter portion 20 is cranked, with the swivel end 64 being directly connected to the sleeve 1 0. As no screw-threaded shank is provided in this embodiment, fine adjustment of the effective overall secured length is only achieved using the vernier arrangement of the holes on the sleeve 10 and the shaft 50.

Claims

1. A telescopic stabilizing device for use with the three point linkage of an agricultural tractor, comprising an elongate sleeve, a shaft telescopically slidable relatively to the sleeve, means for securing the sleeve and shaft relatively to one another to define the effective overall secured length of the stabilizing device, means for effecting fine adjustment of the effective overall secured length of the stabilizing device. and attachment means for mounting the stabilizing device between a draft arm and the chassis of an agricultural tractor.

2. A telescopic stabilizing device as claimed in Claim 1, in which the sleeve and shaft each have a plurality of cooperating holes spaced apart in a direction parallel to the longitudinal axis of the stabilizing device, the holes being adapted to receive a securing pin, and the holes in the shaft being at a different pitch to the holes in the sleeve so as to allow for vernier type variation in the effective overall secured length of the stabilizing device.

3. A telescopic stabilizing device as claimed in Claims 1 or 2, in which the means for effecting fine adjustment comprises or further comprises a screw-threaded shank engaging screw threading at the end of the sleeve remote from the shaft, said shank also providing a means for adjusting the effective minimum unsecured length of the stabilizing device.

4. A telescopic stabilizing device as claimed in Claim 3, in which a vibration counterweight is attached to the sleeve.

5. A telescopic stabilizing device as claimed in Claim 4, in which the vibration counterweight is in the form of a handle which may be used to rotate the sleeve relatively to the screw-threaded shank.

6. A telescopic stabilizing device as claimed in any of Claims 3 to 5, in which the attachment means for mounting the stabilizing device to the chassis of an agricultural tractor is provided on the screw-threaded shank.

7. A telescopic stabilizing device as claimed in Claim 2 or any of Claims 3 to 6 as appendent to Claim 2, in which a pin for engaging a hole in the sleeve and the shaft is attached permanently to the sleeve.

8. A telescopic stabilizing device substantially as herein described with reference to and as shown in the accompanying drawings.

9. A three point linkage for an agricultural tractor, the linkage having a telescopic stabilizing device as claimed in any one of the preceding claims.

1 0. An agricultural tractor having a three point linkage as claimed in Claim 9.