GB2323764A

GB2323764A - Coupling part for the three-point linkage of a tractor

Info

Publication number: GB2323764A
Application number: GB9807291A
Authority: GB
Inventors: Jacques Bachmann
Original assignee: Noremat SAS
Current assignee: Noremat SAS
Priority date: 1997-04-04
Filing date: 1998-04-03
Publication date: 1998-10-07
Anticipated expiration: 2018-04-03
Also published as: FR2761639B1; FR2761639A1; GB2323764B; GB9807291D0

Abstract

The coupling part comprises means (12) for attaching the lower lifting arms (20) of the tractor (T) and means (17) for attaching the machine (M) and is formed overall by a rear shaft 10 bearing the means for attaching the lower lifting arms of the tractor, a front shaft 11 bearing the means for attaching the machine, such that said means for attaching the machine (M) are arranged at the front of said means for attaching the lower lifting arms (20) of the tractor, said rear and front shafts (10, 11) being arranged parallel to one another and connected by struts (14, 15) to form a rigid frame and a bar (16) connects two struts (15) so as to form a frame on which the body of the machine (M) is placed.

Description

COUPLING PART FOR PERMITTING COUPLING OF A MACHINE TO THE THREE-POINT LINKAGE OF A TRACTOR The present invention relates generally to the coupling of an agricultural machine to a vehicle having a device usually referred to as a three-point linkage, for example a tractor.

Some machines, such as mower/scrub-clearers with hydraulic arms, operate on the side of the tractor and are adapted to operate both in the same plane as the plane of travel of the tractor and in a plane inclined downwards relative to the plane of travel of the tractor for cleaning ditches or upwards for cleaning banks. These tools are also suitable for operating arranged at a distance from the ground for lopping branches.

These different modes of operation produce great stresses on the coupling of the tractor due to the lateral offset of the loads. When the machines are of heavy weight, these stresses manage to cause the main lifting axle of the coupling, which is designed to withstand parallel stresses in the same direction, and does not withstand stresses in the opposite direction well, to break.

Furthermore, three-point linkages have fairly large working clearances at the hinge pins of the lifting mechanism, which results in inaccurate manoeuvring of the machine which is detrimental to the quality of work and to the speed of retraction thereof when an obstacle is encountered.

Another difficulty encountered when working with a machine borne by a tractor stems from the fact that it is necessary to position the machine as close as possible to the rear of the tractor so as to improve firstly the stability of the travelling assembly and secondly the visibility of the work when approaching the working zone of the driver. It is difficult to bring it close to the machine owing to the lack of space available between the tractor and the machine which it bears.

In order to overcome these problems, coupling of machines with hydraulic arms to a tractor is frequently effected by means of a rigid connecting piece. This connecting piece has several disadvantages. Firstly, it is adapted to each type of tractor, which means that it cannot be used on different vehicles. Furthermore, it is heavy and therefore difficult to manipulate, and, in order to be positioned on the tractor, requires the removal of the lifting arms thereof. This involves wasting time for removing and remounting the parts of the three-point linkage.

The invention therefore aims to propose a coupling part which permits rapid, simple mounting of a machine, for example a machine with a hydraulic arm, on the three-point linkage of a tractor.

To this end, the invention proposes a coupling part for permitting coupling of a machine to the three-point linkage of a tractor, of the type comprising means for attaching the lower lifting arms of the tractor and means for attaching the machine, characterised in that it is formed overall by a rear shaft bearing the means for attaching the lower lifting arms of the tractor, a front shaft bearing the means for attaching the machine, such that said means for attaching the machine are arranged at the front of said means for attaching the lower lifting arms of the tractor, in that said rear and front shafts are arranged parallel to one another and connected by struts to form a rigid frame and in that a bar connects two struts so as to form a frame on which the body of the machine is placed.

In this description, the concepts of front and rear are defined viewing the elements as arranged in a linkage, the front being defined as the front of the tractor.

The coupling part according to the invention is furthermore noteworthy in that: - the means for attaching the lower lifting arms of the tractor are formed by devises, - the means for attaching the machine are formed by portions of the front shaft, - the front shaft bears means for attaching lateral stabilisers.

The invention will be better understood by means of the description which follows, given by way of non-limitative example, referring to the appended drawings, in which: - Figure 1 is an exploded perspective view of the tractor/coupling part/machine unit before coupling, - Figure 2 is a side view of the tractor/coupling part/machine unit before coupling, - Figure 3 is a side view of the tractor/coupling part/ machine unit after coupling.

Figure 1 shows diagrammatically the tractor T and the machine M which has to be coupled thereto for working, and also the coupling part 1 according to the invention, which is intended to facilitate coupling of said machine to the three-point linkage of the tractor.

As can be seen in the drawing, the coupling part is overall formed of two shafts 10 and 11, a rear and a front one, respectively, arranged parallel to one another and connected by struts 14 and 15 to form a rigid frame.

The rear shaft 10 positioned on the side of the machine M bears at each of its ends means for attaching a lower lifting arm 20 of the tractor T by means of a cotter-pin 22, said means being formed by a clevis 12 in the example illustrated in the drawing.

The third arm of the three-point linkage of the tractor, which is usually referred to as the upper connecting-rod or lifting connecting-rod, has not been shown in the drawings.

It is, in known manner, attached to the attachment means 40 of the machine.

The front shaft 11 arranged on the side of the tractor T bears devises 13 for attaching lateral stabilisers 21 by means of the cotter-pins 23.

Positioning these lateral stabilisers 21 makes it possible to fix the position of the coupling part relative to the tractor by preventing any possibility of rotation thereof relative to the lifting arms and of lateral displacement relative to the tractor.

As can be seen in the drawings, the devises 13 are arranged on the front of the arm 11 and the passages intended for the insertion of the cotter-pin 23 are positioned such that the latter is not parallel to the arm 11. Such an arrangement makes it possible to position the stabilisers practically vertically and to orient them in the most appropriate direction for withstanding the stresses produced during operation of the machine.

The coupling part 1 according to the invention also comprises a bar 16 connecting the struts 15. The upper edges of the struts 15 and of the bar 16 are arranged in one and the same plane so that said struts 15 and the bar 16 form a frame on which the body of the machine M can be placed.

The means for attaching the machine M to the coupling part 1 according to the invention are formed in the example illustrated in the drawings by portions 17 of the front shaft 11 arranged between the crossbars 15 and the devises 13.

The attachment means 30 for the machine M are usually formed by C-shaped parts open towards the front and referred to as hitch jaws.

When coupling the machine, these attachment means 30 are arranged around portions 17 of the front shaft 11 and conical shims 31 are inserted into the openings 32 in order to enclose said front shaft 11 in the hitch jaws.

To couple the machine M, the user attaches the coupling part 1 according to the invention to the lower lifting arms 20 of the three-point linkage of the tractor and then positions the lateral stabilisers 21, taking care to adjust them such that the coupling part is borne by the tractor without any possibility of movement. To finish, the tractor is moved back towards the machine so as to position the front shaft 11 in the hitch jaws 30, and the conical shims are put in place.

In the example of embodiment illustrated in the drawings, the struts 15 are extended forwards by plates 18 which with the devises 13 guide the hitch jaws 30 while the tractor is brought up.

This coupling is very quick and very simple to perform, which enables the user to save time compared with the manoeuvres usually carried out. Since uncoupling is also quick, the user can change machine without wasting time and work with a machine which does not require the coupling part according to the invention. This enables him not to have to immobilise the tractor between two operations effected with a machine requiring a coupling part.

As can be seen in Figure 3, the provision of the means for attaching the machine to the coupling part on the front shaft of said part makes it possible to bring the machine very close to the tractor.

The machine is attached to the coupling part in front of the attachment points for the lower lifting arms of the tractor, and is placed on the frame formed by the struts 15 and the bar 16.

The coupling of the machine to the tractor is then very stable, and the machine operates in a plane closer to the tractor driver, which means that he needs to turn round less frequently to monitor the work.

The machine M coupled to the tractor by means of the coupling part 1 according to the invention is held perfectly during working. The displacements due to the play of the coupling are cancelled out, which enables the machine to operate under beneficial conditions and to retract effectively when an obstacle is encountered.

The stabilisers are arranged practically vertically in order to take up the stresses appropriately, which avoids breakage of the lifting means of the tractor.

Claims

1. A coupling part for permitting coupling of a machine to the three-point linkage of a tractor, of the type comprising means for attaching the lower lifting arms of the tractor and means for attaching the machine, characterised in that it is formed overall by a rear shaft bearing the means for attaching the lower lifting arms of the tractor, a front shaft bearing the means for attaching the machine, such that said means for attaching the machine are arranged at the front of said means for attaching the lower lifting arms of the tractor, in that said rear and front shafts are arranged parallel to one another and connected by struts to form a rigid frame and in that a bar connects two struts so as to form a frame on which the body of the machine is placed.

2. A coupling part according to Claim 1, characterised in that the means for attaching the lower lifting arms of the tractor are formed by devises

3. A coupling part according to Claim 1 or Claim 2, characterised in that the means for attaching the machine are formed by portions of the front shaft.

4. A coupling part according to any one of Claims 1 to 3, characterised in that the front shaft bears means for attaching lateral stabilisers.

5. A coupling part for permitting coupling of a machine to the three-point linkage of a tractor, substantially as herein described with reference to the accompanying drawings.

6. A machine to be coupled to the three-part linkage of a tractor having a coupling as claimed in any preceding claim.