GB2076343A - A tailgate mechanism for a tipping container on a vehicle, such as an agricultural tractor - Google Patents

Abstract

Pivotal transmission linkage (22, 34, 38) is interposed between the tailgate (18) and a fixed part of the vehicle, e.g. the chassis (10), to be responsive to tripping of the container (14) to cause the tailgate to open by turning thereof about a pivotal support (20) on which said tailgate is mounted to the container. The invention is characterised by an arm (22) forming part of the linkage, which arm is operatively driven by a cam (42) as the container tips. The arm is driven only during a predetermined initial tipping movement of the container, e.g. the first 11 degrees, whereafter the cam disengages the arm, which thereafter remains fixed against a stop (50). While the arm is being driven, the linkage mechanism acts to hold the tailgate locked closed, but with further tipping of the container after the predetermined initial tipping movement during which the arm (22) is stationary against the stop, the remaining parts (34, 38) of the linkage drive the tailgate open. A reverse procedure occurs when the container is restored to its rest or untipped position. <IMAGE>

Description

SPECIFICATION Improvements in tailgate mechanisms Field of the invention This invention relates to a tailgate mechanism for a tipping container on a vehicle.

Background Conventionally, an openable tailgate of a tipping container on a vehicle starts to open immediately the container starts to tip. This can be disadvantageous, especially for example in the case of an agricultural trailer, since the tractor driver is often unable clearly to see where the load is being deposited until the container has been tipped sufficiently to afford a clear sight line from the driving position on the tractor to the unloader point at the back of the trailer. It is an object of the present invention to provide a tailgate mechanism for a tipping container on a vehicle whereby the above-described disadvantage is substantially avoided.

The invention According to the invention, there is provided a tailgate mechanism for a tipping container on a vehicle, comprising a pivotal transmission' linkage interposed between a fixed part of the vehicle and the tailgate, whereby the tailgate is opened and closed in dependence on tipping of said container, wherein the transmission linkage includes an arm which is operatively driven by the tipping container only during a predetermined initial tipping movement thereof in such a manner as to maintain the tailgate end of the transmission mechanism in substantially fixed relationship to the container, thereby to hold the tailgate closed during said predetermined initial tipping movement.

With the mechanism in accordance with the invention, unloading is not commenced until after the container has been tipped to an extent sufficient to provide the driver with a clear view, beneath the partially tipped container, of the unloading point. A convenient angle of tip sufficient to afford such a sightline will usually be between 7 and 1 5 degrees, preferably between 9 and 1 3 degrees, and nominally may be substantially 11 degrees. In the case of an agricultural trailer, this will be about one quarter of the fully tipped angle of the container, which may be about 42 degrees, tipping being effected as the transmission linkage drives the tailgate about a pivot on which the tailgate is mounted on the container.Conveniently, said pivot is constituted by a pivotal connection between the container and a member fixed to a part of the transmission linkage. Such a transmission linkage may comprise the said arm, which at one end is pivotted to the fixed part of the vehicle, a push-pull rod pivotted at one end to the other end of said arm, and a strut fixed to the tailgate which is pivotally connected to the other end of said rod, while the driving means for the said arm may take the form of a cam plate moving with the tipping container, the cam drive being disengaged at the end of said predetermined initial tipping movement. A stop may be provided for the said arm to prevent further pivotal movement thereof after disengagement of the cam drive.

In the accompanying drawings: Figure 1 is a diagrammatic side view of a practical embodiment of tailgate mechanism on a tipping container on an agricultural trailer; and Figure 2 is an an end view of the mechanism on one side of the trailer, to a larger scale.

Decription of embodiment In Figs. 1 and 2, only the parts of the structure of the trailer relevant to the tailgate mechanism are illustrated. This trailer has a chassis referenced 10, with part of one wheel illustrated at 1 2 in Fig. 1. A container 14 is pivotally mounted to tip relative to the chassis 10, the container pivot being referenced 16.

The container 14 has an openable and closable tailgate 18, pivotally mounted to the container about a pivotal support 20. The present invention is concerned with a mechanism whereby the tailgate 18 is opened in dependence on the tipping movement of the container 14.

This mechanism comprises a pivotal transmission linkage which includes, on each side of the trailer, an arm 22 fixed by an end plate 24 to a torque tube 26 which can turn in a support member 28 fixed to the vehicle chassis, of which one chassis member is indicated at 30. This form of mounting provides a pivot 26 for one end of the arm 22, the other end of which is pivotally connected at 32 to one end of a cranked push/pull rod 34, the other end of which is pivotally connected at 36 to a strut 38 fixed to the tailgate 1 8. A second strut-like link to the tailgate is indicated at 40.

Conveniently, a plate member 41 fixed between the two struts constitutes the means by which the tailgate is mounted on the pivotal support 20.

The arm 22 is adapted to be driven, preferably on one side of the trailer only, by a cam plate 42 mounted on a cam plate bracket 44 fixed to an extension 46 of the body of the container 1 4. A container body member is indicated at 48 in Fig. 2. The cam plate 42 is lifted when tipping of the container 14 is commenced, about its pivot 16, by a drive (not shown) derived from a tractor (not shown) in front of the trailer, this cam plate bearing on the pivotal joint 32 connecting the arm 22 with the rod 34 to turn the arm 22 about its fixed pivot 26 from the position shown in full line to the position 22A shown in dotted line.When the container 14 has tipped a predetermined amount from its normal untipped or rest position, conveniently 11 de grees, the cam plate 42, at position 42A, disengages the pivotal joint 32, and the arm 22 comes to rest against a fixed stop member 50. The cam plate 42 continues to lift as tipping of the container 14 continues up to a maximum tipped angle of about 42 degrees, but the arm 22 is no longer driven and remains in its rest position against the stop 50.

When, with the container tipped by 11 degrees, the arm 22 moves to the position 22A, the push/pull rod 34 moves to the position 34A shown in dotted line and the pivotted strut 38 moves to the position 38A shown in dotted line. The tailgate pivot moves to the position indicated at 20A. The linkage mechanism 22, 34, 38 is designed and dimensioned so that, as the parts thereof move from the positions shown in full line to the positions 22A, 34A, 38A, the tailgate end of the strut 38, which is fixed to the tailgate 18, remains in a substantially fixed position relative to the container. Thus, the position of the tailgate, with the container tipped by 11 degrees, is indicated in dash-dot line at 18A. At this time the container 14 remains locked closed by the tailgate, so that the dash-dot line 1 8A is equally indicative of the rear end of the container body.

However, with the arm 22 effectively fixed after the initial tipping movement (11 degrees) of the container 14 has been completed, continued tipping of the container causes the linkage mechanism 22, 34, 38 to drive the tailgate 1 8 open by turning it about its pivotal support 20 on the container. At the maximum tipped angle of 42 degrees, the.

position of the rear end of the container body is indicated by dash-dot line 1 4B and the position of the tailgate is indicated by dashdot line 18B. At this time, the tailgate pivot is at the position 20B, the line of the push/pull rod 34 being indicated at 34B.

It may be considered that the movement of the arm 22, during the predetermined initial tipping movement of the container 14, substantially compensates for or counteracts the driving couple applied to the tailgate 1 8 about its pivot 20 by the pivotally connected rod 34 and strut 38.

When the container 1 4 is lowered to its untipped or rest position, the mechanism operates in reverse. Closure of the tailgate 1 8 is completed when the tipping angle is reduced to 11 degrees, and thereafter the strut 38 turns with the container 14 about the pivot 16, so that the arm 32 is caused to follow the descending cam plate 42 finally to resume the position shown in full line in Fig. 1.

The advantage of the arrangement is that the operator, from the driving position on the tractor, can gain a clear sight-line beneath the container to the unloading position at the rear of the trailer when the container has been tipped to an angle approaching 11 degrees, before unloading actually commences. The position of the trailer can be re-adjusted as necessary before tipping of the container is continued beyond 11 degrees to commence opening of the tailgate.

Various modifications of the above-described arrangement are possible within the scope of the invention. In particular, the in- vention is not restricted to tipping containers on agricultural tractors, and especially when applied to other vehicles, differing forms of pivotal transmission linkage may be employed, together with differing forms of drive from the container for the arm of said linkage which is positively driven during the predetermined initial tipping movement.

It has already been indicated above that one object of the present invention (in providing the initial tailgate opening delay) is to allow the tractor driver when reversing to an unloading position, to tip the body to an angle of up to 11" and thereby provide a clear sight line from the driving- position, below the partially tipped body and to the unloading point behind the trailer. In addition, however, this invention provides shear pin protection for the taildoor, to prevent it from being bent when the body is being lowered and when produce, such as sugar beet, remains in the way of the tailgate closing. It is in fact this which causes most automatic tailgates to become bent and no longer grain proof.

Delayed opening of the tailgate can be provided by a hydraulic ram mechanism, but this can be extremely dangerous if the driver should fail to operate it, allowing the produce to fall out of the trailer before the trailer body and load centre of gravity gets behind the pivot point of the tandem axle. Thus the present invention provides safety for the machine and the operators.

The cross shaft ensures that whatever pressure arises on one side (as a result of produce being lodged in the tail of the cart when the taildoor is closing) it does not provide a twisting action to the taildoor through the arms which control the opening and closing of it.

There are situations when the tailgate has to be operated in a conventional manner. This can be achieved by simply locking the cam to stop it working.

If the tailgate is to be locked to allow grain to be discharged through a shutter in the closed tailgate then the connecting rod can be detached from the cam end and bolted so as to lock the tailgate shut.

Claims (8)

1. A tailgate mechanism for a tipping container on a vehicle, comprising a pivotal trans mission linkage interposed between a fixed part of the vehicle and the tailgate, whereby the tailgate is opened and closed in dependence on tipping of said container, wherein the transmission linkage includes an arm which is operatively driven by the tipping container only during a predetermined initial tipping movement thereof in such a manner as to maintain the tailgate end of the transmission mechanism in substantially fixed relationship to the container, thereby to hold the tailgate closed during said predetermined initial tipping movement.

2. A mechanism according to claim 1, wherein said transmission linkage is adapted to open and close the tailgate by pivotally moving said tailgate about a pivot on which said tailgate is mounted to the container, said pivot being formed between the container and a part of the transmission linkage or part carried thereby.

3. A mechanism according to claim 1 or claim 2, including driving means for said arm in the form of a cam plate moving with the tipping container, the cam drive being disengaged at the end of said predetermined initial tipping movement.

4. A mechanism according to any of claims 1 to 3, wherein the linkage comprises the said arm, which at one end is pivotted to the fixed part of the vehicle, a push-pull rod pivotted at one end to the other end of said arm, and a strut fixed to the tailgate which is pivotally connected to the other end of said rod.

5. A mechanism according to any of claims 1 to 4, wherein said predetermined initial tipping movement is between 7 and 1 5 degrees, preferably between 9 and 1 3 degrees and is nominally 11 degrees.

6. A mechanism according to any of claims 1 to 5, including a stop for the said arm to prevent further pivotal movement thereof after disengagement of the cam drive.

7. A mechanism according to any of claims 1 to 6, wherein the vehicle is an agricultural trailer having a container mounted to tip relative to the chassis, which container is adapted to be tipped by a power drive derived from a tractor.

8. A tailgate mechanism for a tipping container substantially as hereinbefore described with reference to the accompanying drawings.