IES83702Y1 - A towing hitch assembly - Google Patents

Description

A TOWING HITCH ASSEMBLY The invention relates to towing hitches for vehicles e.g. agricultural tractors. In particular, the invention relates to pick-up hitches for agricultural prime movers such as tractors or similar prime movers for towing agricultural machinery such as a trailer in which the tow arm of the trailer is engaged by a moveable drawbar of the hitch and is lifted from an unhitched or rest position on or near the ground by the Vehicle hydraulics into a position for towing.

In the specification, the expressions, "raised", "lowered", "forward of "rearward of‘. "in front of‘ and "behind", "to the front of’ or "to the rear of‘ as used herein refer to the relative positions when the towing hitch is mounted for use on a vehicle e. g. a tractor, the front and rear of the vehicle being in respect of the forward direction of travel of the vehicle.

A known form of a towing hitch disclosed, for example, in EP 0138519 and GB 2218890 is based on a principal that the hitch assembly comprises an upper fixed part rigidly connected to the vehicle and a lower moveable part for engaging a tow arm of a trailer or an agricultural appliance. The lower movable part is pivotally mounted on the upper fixed part and is pivotable about the longitudinal axis of the pivot. The lower movable part is lifted from a lower rest position to an upper hitched position by a vehicles hydraulic system via a series of levers and linkages and is secured in position by a latch or a clevis.

In other variations, telescopic lift arms or rods operated by the vehicles hydraulic system are required in order to bring the movable part of the hitch mechanism into the upper towing position.

However, in many instances, compact size of a vehicle does not allow the use of a complex lever system for lifting the lower part of the hitch assembly into a position for engaging a tow arm of a trailer. Therefore an efficient solution is required in order to reduce the number of levers and linkages of hitch assembly without affecting the quality of its operation so that its parts do not interfere with the vehicles cab floor and walls.

Therefore it is an object of the present invention to alleviate the disadvantages of the prior art.

Accordingly, the present invention provides a towing hitch assembly for a vehicle, the assembly comprising an upper fixed part rigidly mountable on the vehicle and a lower movable part with a towing element for engaging a tow arm of a trailer, the lower movable part being pivotally connected with the upper fixed part about a first pivot axis, whereby, in use, the lower movable part is pivotable about the longitudinal axis of the first pivot such that the lower moveable part can be lifted from a lower rest position to an upper towing position, the lower movable part being securable in the upper hitched position by a latch means, characterised in that a hydraulic ram mechanism is provided in front of the lower moveable part and towards the front of the hitch assembly, the hydraulic ram mechanism being pivotably connected to the lower moveable part about a second pivot axis.

Conveniently, the second pivot axis is located transversely along the front side of the lower moveable part.

Such an arrangement has an advantage that it allows for a reduced number of levers and linkages in the hitch assembly of the invention so that the parts of the assembly do not interfere with cab floor and walls.

Conveniently, the towing element comprises a hook.

Ideally, the upper fixed part is provided with a means for securing the tow arm of the trailer in position when the tow aim is engaged by the hook of the lower movable part of the towing hitch assembly.

Conveniently, in a preferred embodiment of the invention, in use, the towing hitch assembly is mountable on a vehicle in such a manner that the front part of the assembly including the hydraulic ram mechanism is located under a floor of the vehicle’s cab.

Advantageously, the piston of the hydraulic ram has a connecting rod connected with the lower movable part of the hitch assembly via a hinge arrangement. Ideally, the hinge arrangement comprises a hinge pin and links connecting the hinge with the lower movable part. Conveniently, the links are pivotably mounted on the hinge pin. Ideally. connecting rod has its one end mounted on the hinge pin. The connecting rod, moving forwardly within the cylinder of the hydraulic ram, forces the links move upwardly in the vertical plane of the hitch mechanism. Thus, the links lift the lower movable part, pivotable about the longitudinal axis of the pivot of the upper fixed part, from the lower rest position to the upper hitched position.

Ideally, in the preferred embodiment of the invention, the hydraulic ram mechanism of the towing hitch assembly is pivotally connected to the front part of the upper fixed part of the hitch assembly at a third pivot axis.

Conveniently, the lower movable part and the hydraulic ram mechanism are positioned at an obtuse angle with regard to each other when the lower movable part is in its rest position. The hydraulic ram mechanism, simultaneously, is positioned at an angle to the ground. When the lower movable part is lifted into the upper hitched position, the hydraulic ram mechanism, being pivotable about the third pivot axis provided at the front part of the upper fixed part of the hitch assembly, aligns with the lower movable part.

Conveniently, in the preferred embodiment of the invention a latch is provided for securing the lower movable part of the hitch assembly in the upper hitched position.

The invention will now be described more particularly with reference to the accompanying drawings, which show, by way of example only, one embodiment of the towing hitch assembly of the present invention.

In the drawings: Figure l is a perspective view of a towing hitch assembly of the invention in a hitched/ towing mode, Figure 2 is perspective view of the towing hitch assembly of the invention in a rest mode; Figure 3 is a cross-sectional side View of the towing hitch assembly shown on Figure 1.

Figure 4 is a plan view of the towing hitch assembly shown on Figure 1; Figure 5 is a rear view of the towing hitch assembly of Figure 1; Figure 6 is a side view of the towing hitch assembly of Figure 2.

Referring initially to Figure 1 and Figure 2 of the drawings, the towing hitch assembly of the invention is indicated generally by reference numeral 1 and comprises an upper fixed part 2 and a lower movable part 3, the latter having a hook 31 for engaging a tow arm of a trailer (not shown). The lower movable part 3 is connected with the upper fixed part 2 by means of a pivot pin 4 positioned horizontally across the upper fixed part 2 and mounted within cylindrical sleeves 210 and 220 of the upper fixed part 2 and a cylindrical sleeve 35 of the lower movable part 3. The lower movable part 3 is rotatable about the longitudinal axis of the pivot pin 4 and can be lifted from a lower rest position (as in Figure 2) to an upper hitched position (as in Figure 1) by a hydraulic ram mechanism 5 via a hinge connection 7 (see Figure 3 and Figure 4), The hydraulic ram mechanism 5 is arranged in front of the lower movable part at the front of the hitch assembly 1. A latch mechanism 6 is provided in the towing hitch assembly 1 for retaining the lower movable part 3 in the upper hitched position. The pivot pin 4 is secured within cylindrical sleeves 21 O and 220 by pins 230 and 240 respectively.

The upper fixed part 2 comprises two side plates 21 and 22, a vertical plate 23, two side horizontal plates 24 and 25, a front horizontal plate 26 and a rear plate 27; and the lower movable part 3 comprises two side plates 32 and 33, a front plate 31, on which the hook 31 is fixed, an upper plate 36 and a bottom plate 37.

The towing hitch assembly 1 is mountable on a vehicle by the vertical plate 23 and the horizontal plates 24 and 25 in such a manner that the front part of the assembly containing the hydraulic ram mechanism 5 is located under a cab floor.

The lower movable part 3 is pivotable about the longitudinal axis of the pivot pin 4 while the upper fixed part 2 remains still.

A depression 28 is provided in the edge of the front horizontal plate 34 of the lower movable pan 3, so that a hook 31. when the lower movable part 3 is in the upper hitched position, occupies the depression 28 in order to secure the tow arm of the trailer in the towing position.

Referring now to Figure 3, Figure 4 and Figure 6, the hydraulic ram mechanism 5 comprises a cylinder 55, a ram piston 51, a connecting rod 50 of which is pivotally connected with the hinge arrangement 7 of the towing hitch assembly 1. The hinge arrangement 7 comprises a hinge pin 71 to which a cylindrical end 501 of the connecting rod 50 is secured by a pin 72. Two links 38 and 39 of the lower movable part 3 are mounted on the hinge pin 71 thereby allowing the lower movable part pivot about the longitudinal axis of the hinge pin 71. The cylindrical end 501 of the connecting rod 50 is mounted on the intermediate portion of the pin 71. The links 38 and 39 are mounted on the hinge pin 71 at either side of the cylindrical end 501.

When the ram piston 51 is in a retracted position within the cylinder 5, the lower movable part 3 of the towing hitch assembly is in the lower rest position (as in Figure 6). When a driver of the vehicle operates vehicle's hydraulic system, a hydraulic liquid is supplied into a rear chamber 54 of the hydraulic ram mechanism via an inlet manifold 53 and withdrawn from a front chamber 56 via an outlet manifold 52. Thus, the ram piston 51 and the connecting rod 50 move forwardly, as indicated by arrow 100 in Figure 6, within the cylinder 55. The connecting rod 51, moving forwardly in the cylinder 5, forces the links 38 and 39 move upwardly and backwardly, as indicated by arrow 300 in Figure 6, thereby lifting the lower movable part, rotatable about the longitudinal axis of the pivot pin 4, into the upper hitched position (as in Figure 4).

The cylinder 55 of the hydraulic ram mechanism 5 is pivotally moveable about a pivot pin 8 at the front end of the cylinder 55. The pivot pin 8 is secured in cylindrical sleeves 250 and 26() of the upper fixed part 2 of the towing hitch assembly 1 and the cylinder 5 is mounted on the intermediate portion of the pivot pin 8 by a cylindrical sleeve 57. The lower movable part 3 and the hydraulic ram mechanism 5 are positioned at an obtuse angle with regard to each other when the lower movable part 3 is in its unhitched lowered position. The hydraulic ram mechanism 5, simultaneously, is positioned at an angle to the ground. When the lower movable part 3 is being lifted into the upper hitched position, the hydraulic ram mechanism 5 being moveable about the pivot pin 8 aligns with the lower movable part 3 in the upper hitched position.

Figure 5 is a rear view showing the towing hitch mechanism 1 of the invention with its lower movable part 3 in the upper hitched position.

The towing hitch assembly can be provided with a latch mechanism 6 for retaining the lower movable part in the upper hitched position, one embodiment of which latch mechanism is illustrated in the drawings. The latch mechanism 6 comprises two hooks 61 fixed vertically on the upper plate 36 of the lower movable part 3 and a plate 62. of a rectangular shape, mounted across the front horizontal plate 26 of the upper fixed part 2.

The plate 62 is mountable at an angle to the horizontal plate 26. The plate 62 can be provided with a spring mechanism (not shown). When the lower movable part 3 is being lifted into the upper hitched position, the hooks 61 cross the front horizontal plate 26 of the upper fixed part 2 via apertures 261 provided in the front horizontal plate 26. Top portions 610 of hooks 61 tilt the plate 62 rearwards thereby compressing springs of the spring mechanism. When the top portions 610 of the hooks 61, moving upwardly, come out of contact with the plate 62, the spring mechanism is released and the plate 62 is tilted back into its initial position. The hooks 61, then, are lowered slightly so that their inner portions 611 engage an edge 64 of the plate 62 thus securing the lower movable part 3 in the upper hitched position. When it is necessary to bring the lower movable part 3 into its rest position, the lower movable part is moved slightly upwards by operating the hydraulic ram mechanism 5, as indicated by arrow 600 on Figure 4, thereby disengaging the hooks and the plate 62 and allowing the lower movable part 3 to be brought down into its lower rest position.

The hydraulic ram mechanism 5 employed in the towing hitch assembly of the invention can be of various sizes. The bigger the cylinder 55 of the hydraulic ram 5, the quicker and easier it is to operate the towing hitch assembly 1.

It will of course be understood that the invention is not limited to the specific details described above and that various modifications and alterations are possible without departing from the scope of the invention as defined in the appended claims.

A?‘ 733

Claims (2)

CLAIMS: A towing hitch for a vehicle comprising an upper fixed part rigidly mountable on the vehicle and a lower movable part with a towing element for engaging a tow arm of a trailer, the lower movable part being pivotally connected to the upper fixed part by a first pivot means to enable the lower movable part to be pivotable about the longitudinal axis of the first pivot means so that the lower movable part is liftable from a lower rest position to an upper towing position, the lower movable part being securable in the upper towing position by a latch means; and the lower movable part being pivotally connected to a hydraulic ram means by a second pivot means with the hydraulic ram means being operable to lift the lower movable part from a lower rest position to an upper towing position. A towing hitch as claimed in Claim 1, in which the longitudinal axis of the first pivot means is located substantially across both the upper fixed part and the lower movable part; the longitudinal axis of the second pivot means is located substantially across the lower movable part; optionally the hydraulic ram mechanism is operable to release the latch means, so that the lower movable part can return from the upper towing position into the lower rest position; optionally, the hydraulic ram mechanism is located proximal the front end of the towing hitch; optionally the towing element comprises a hook; and optionally, in use, the upper fixed part is mountable on a towing vehicle in such a manner that a greater part of the towing hitch including the front end and the hydraulic ram is located under a floor of the vehicle’s cab. A towing hitch as claimed in

1.Claim 1 and

2.Claim 2, in which the piston of the hydraulic ram is connected to the second pivot means by a connecting rod; optionally the second pivot means comprises a hinge arrangement, the hinge arrangement having a hinge pin and one or more links, said links connecting the hinge with the lower movable part, the links being pivotally mounted on the hinge pin at one end and fixedly mounted on the lower movable part at the other end; optionally the connecting rod has its one end mounted on the hinge pin; and optionally the connecting rod is operable by the hydraulic ram to force the lower movable part via the hinge arrangement to move upwardly from the lower rest position to the upper towing position, while the lower movable part pivots about the first pivot means. A towing hitch as claimed in any of the preceding claims, in which the hydraulic ram mechanism is pivotally connected to the upper fixed part proximal the front end of the towing hitch via a third pivot means; optionally the lower movable part and the hydraulic ram mechanism are positioned at an obtuse angle with regard to each other when the lower movable part is in the lower rest position; optionally the hydraulic ram mechanism is adapted to pivot about the longitudinal axis of the third pivot while the lower movable part is being lifted from the lower rest position into the upper towing position; and optionally the hydraulic ram mechanism is adapted to align with the lower movable part when the latter reaches the upper towing position. A towing hitch substantially in accordance with the embodiment as herein described with reference to and/or as shown in the accompanying drawings. MACLACHLAN & DONALDSON Applicants‘ Agents,