GB1568052A - Couplings - Google Patents

Description

(54) IMPROVEMENTS RELATING TO COUPLINGS (71) We, IAN WILLIAM PARKER and PAUL ANTHONY WITNEY, of Home Farm, Rimpton, Yeovil, Somerset, and Pillinge Farm, South Brewham, Bruton, Somerset, both British Subjects, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be par riculary described in and by the following stateteat : - This invention relates to coupling devices.

It is primarily concerned with the kind of coupling which has been proposed for tractors where two A-frames are arranged to interengage This enables the attachment of an implement to be automatically carried out by the driver manipulating the controls for the three-point linkage at the rear or the lifting fork at the front These A-frames are designed so that the one mounted on the tractor can be moved into registry underneath the other frame rigidly secured to the implement, and this is done by moving the tractor itself. Then the tractor A-frame is raised and its sloping side seat snugly within the downwardly facing chamzsl members which form the sides of the A-frame on the implements. The latter can then be raised pulled or pushed as ap pswriate. While this provides a secure attachment in most respects, it is of course vulnerable to the implement being forced to rise in relation to the tractor A-frame, for example by engagement with an obstruction on the ground. Therefore, once the frames are fully mated it is advisable to provide a lock to hold them together.

It is an object of this invention to provide ,,cch a lock, and one which can be operated by the driver of the tractor without having to dissent.

According to the present invention there is provided a tractor implement coupling device comprising a first coupling A-frame for connection to the front lifting fork or the three point linkage of a tractor, a second coupling A-frame for connection to an implement, the first coupling frame being arranged to be moved upwardly into interengagement with the second coupling frame, a spring loaded plunger centrally mounted on the cross bar of the first coupling frame, the spring action urging the plunger normal to the plane of the frame and, in use, towards the second coupling frame, a horizontal lever overlying and pivoted at one end to said first frame cross bar, coupled at an intermediate point to said plunger and having a flexible pulling element connected to its other end to lead to the tractor driver for retracting the plunger with mechanical advantage against the spring action, a detent provided by the cross bar of the second coupling frame with which said plunger registers when the frames are interengaged to prevent frame disengagement, and cam means for temporarily retracting the plunger as the frames engage.

For a better understanding of the invention one constructional form will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a front elevational view of an A-frame coupling in the disengaged state, and having the locking system according to the invention, and Figure 2 is a plan view partly broken away, of the coupling of Figure 1.

The coupling shown in the drawing consists of two A-frames 1 and 2, the frame 1 being attached, in use, to a tractor, and the frame 2 being provided on an implement. The attachment of the frame 1 may be to a front lifting fork of a tractor, and it may be permanently welded on or be removably fitted, as by bolts.

Alternatively, the frame could be attached to the three-point linkage that is provided at the rear of many tractors. The upper link would be coupled to the apex of the frame while the lower links would be coupled to the lower corners. The frame 2 may be built into the implement or it may be a removable headstock.

The inclined sides 3 of the implement frame 2 are channel members opening downwardly and inwardly, and the cross member 4 and the remainder of the implement is on the side of the channels remote from the tractor, so that the frame 1 can be moved in the direction A in Figure 2 to register directly beneath the frame 2. It can then be raised in the direction B in Figure 1 by the front lifting fork or the rear three point linkage to mate with the frame 2.

The base cross beam 5 of the tractor frame 1 has mounted thereon a spring loaded pin or plunger 6, the spring being contained in a cylinder 7 and the working end of the pin projecting towards the implement. The other end of the pin projects from the cylinder towards the tractor and is coupled to a lever 8 mounted over and extending generally along the beam 5. One end of the lever is pivoted on a bracket 9, and a lanyard 10 is attached to the other end, and this can be led to a convenient point near the drivers seat. The pin 6 is coupled to the lever 8 near the pivot point, and so there is considerable mechanical advantage when the lanyard is pulled. The spring can therefore be powerful to provide sure locking.

The pin is arranged to engage in a hole 11 in a cross member 12 (which may be part of the implement itself) spanning the upper part of the frame 2. Its working end is angled to face upwardly and away from the tractor so that as the frame 1 is raised into the frame 2 that working end acts as a cam surface on the lower edge of member 12 and the pin is pressed back into the cylinder against the action of the spring. As soon as the pin registers with the hole 11, which is only when the frames are fully mated, it shoots back and the locking is complete.

Alternatively, the member 12 may provide an angled surface that will force the pin, which may then be squareended, to retract before shooting back into the hole 11.

In both cases, for release the lanyard is pulled while the lifting fork or three-point linkage is lowered to withdraw the frame 1 from the frame 2.

WHAT WE CLAIM IS :- 1. A tractor implement coupling device comprising a first coupling A-frame for connection to the front lifting fork or the three point linkage of a tractor, a second coupling A-frame for connection to an implement, the first coupling frame being arranged to be moved upwardly into interengagement with the second coupling frame, a spring loaded plunger centrally mounted on the cross bar of the first coupling frame, the spring action urging the plunger normal to the plane of the frame and, in use, towards the second coupling frame, a horizontal lever overlying and pivoted at one end to said first frame cross bar, coupled at an intermediate point to said plunger and having a flexible pulling element connected to its other end to lead to the tractor driver for retracting the plunger with mechanical advantage against the spring action, a detent provided by the cross bar of the second coupling frame with which said plunger registers when the frames are interengaged to prevent frame disengagement, and cam means for temporarily retracting the plunger as the frames engage.

2. A tractor implement coupling device substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. beneath the frame 2. It can then be raised in the direction B in Figure 1 by the front lifting fork or the rear three point linkage to mate with the frame 2. The base cross beam 5 of the tractor frame 1 has mounted thereon a spring loaded pin or plunger 6, the spring being contained in a cylinder 7 and the working end of the pin projecting towards the implement. The other end of the pin projects from the cylinder towards the tractor and is coupled to a lever 8 mounted over and extending generally along the beam 5. One end of the lever is pivoted on a bracket 9, and a lanyard 10 is attached to the other end, and this can be led to a convenient point near the drivers seat. The pin 6 is coupled to the lever 8 near the pivot point, and so there is considerable mechanical advantage when the lanyard is pulled. The spring can therefore be powerful to provide sure locking. The pin is arranged to engage in a hole 11 in a cross member 12 (which may be part of the implement itself) spanning the upper part of the frame 2. Its working end is angled to face upwardly and away from the tractor so that as the frame 1 is raised into the frame 2 that working end acts as a cam surface on the lower edge of member 12 and the pin is pressed back into the cylinder against the action of the spring. As soon as the pin registers with the hole 11, which is only when the frames are fully mated, it shoots back and the locking is complete. Alternatively, the member 12 may provide an angled surface that will force the pin, which may then be squareended, to retract before shooting back into the hole 11. In both cases, for release the lanyard is pulled while the lifting fork or three-point linkage is lowered to withdraw the frame 1 from the frame 2. WHAT WE CLAIM IS :-

1. A tractor implement coupling device comprising a first coupling A-frame for connection to the front lifting fork or the three point linkage of a tractor, a second coupling A-frame for connection to an implement, the first coupling frame being arranged to be moved upwardly into interengagement with the second coupling frame, a spring loaded plunger centrally mounted on the cross bar of the first coupling frame, the spring action urging the plunger normal to the plane of the frame and, in use, towards the second coupling frame, a horizontal lever overlying and pivoted at one end to said first frame cross bar, coupled at an intermediate point to said plunger and having a flexible pulling element connected to its other end to lead to the tractor driver for retracting the plunger with mechanical advantage against the spring action, a detent provided by the cross bar of the second coupling frame with which said plunger registers when the frames are interengaged to prevent frame disengagement, and cam means for temporarily retracting the plunger as the frames engage.

2. A tractor implement coupling device substantially as hereinbefore described with reference to the accompanying drawing.