GB2234722A

GB2234722A - Towing assembly having limited compliance in vertical and lateral directions

Info

Publication number: GB2234722A
Application number: GB8915423A
Authority: GB
Inventors: Dennis Stanley Garrison
Original assignee: GARRISON Ltd
Current assignee: GARRISON Ltd
Priority date: 1989-07-05
Filing date: 1989-07-05
Publication date: 1991-02-13
Also published as: GB8915423D0

Abstract

A towing assembly comprises a first part adapted to be secured rigidly to the towing vehicle, and a second part adapted to be secured to the towed vehicle. The first part comprises a frame element (6) adapted to be bolted to the rear of the towing vehicle, and a towing element in the form of a ball (8), connected to the frame element (6) through the intermediary of a first mounting device (10) and a second mounting device (12). The first mounting device (10), comprising a four-bar linkage, permits the towing element (8) to move vertically relative to the frame element (6) tending to reduce vertical shock loading, whilst the second mounting device (12) permits the ball element (8) to move in a direction generally widthwise of the vehicle, tending to reduce snaking. <IMAGE>

Description

Title: "Towing Assembly" Description of Invention This invention is concerned with improvements relating to towing assemblies.

In the towing of vehicles (such as the towing of caravans by car) it is conventional practice to secure between the towing vehicle and the towed vehicle a towing assembly which may typically comprise a ball and socket joint.

Thus conventionally used is a towing assembly comprising a first part comprising a frame element adapted rigidly to be secured to the towing vehicle and a first cooperative element, a second part comprising a frame element adapted to be secured to the towed vehicle and a second cooperative element, and means to secure the two cooperative elements together in a manner in which they are free to pivot, but are constrained against relative separat.ve movement. Such an assembly is hereinafter referred to as being a towing assembly of the kind specified.

Typically the first cooperative element may comprise a ball and the second cooperative element may comprise a socket adapted to be secured over the ball, locking means being provided to prevent separative movement.

One of the problems encountered in a towing assembly of the kind specified is that undesired movement of the towed vehicle is transmitted to the towing vehicle, which can be dangerous, and it is one of the various objects of this invention to overcome or reduce this problem in a convenient manner.

For example, when the wheels of the towed vehicle encounter road surface irregularities, the vertical movement of the towed vehicle (such as bounce) may tend momentarily to lift, then depress the rear of the towing vehicle, causing a potential hazard.

According to this invention there is provided a towing assembly of the kind specified, wherein at least one of the cooperative elements is mounted in a manner whereby it may undergo limited vertical movement relative to its associated frame element.

Thus the first cooperative element (e.g. the ball) may be connected to the towing vehicle through the intermediary of the device permitting such vertical movement, e.a. through the intermediary of a four-bar linkage. In this manner in the event of vertical movement of the towed vehicle, the two cooperative elements will jointly undergo vertical movement reducing the application of vertical forces to the towed vehicle, and without disruption to the towing action.

Alternatively or in addition the second cooperative element (e.g. the socket) may be connected to the towed vehicle through the intermediary of such a device.

Preferably means is provided to urge said one cooperative element relative to its associated frame element into an optimum position, conveniently by the use of a spring-urged fluid piston/cylinder device. The effect of such a means is to "smooth" undesired vertical forces between the towing and towed vehicles.

In a conventional towing assembly of the kind specified, both the cooperative elements are secured to their respective vehicles in a relatively rigid disposition as far as movement in a widthwise direction is concerned.

Thus should (e.g.) the towed vehicle be subjected to side pressure causing it to "snake", sideways forces will be applied to the rear of the towing vehicle.

Thus according to another aspect of this invention there is provided a towing assembly of the kind specified, wherein at least one of the cooperative elements is mounted in a manner whereby it may undergo limited movmement in a direction generally widthwise of the vehicle to which it is secured.

Thus, the first cooperative element (e.g. the ball) may be connected to the towing vehicle by a pivot mechanism having a vertical axis, the first cooperative element being spaced longitudinally from the axis of the pivot, allowing the first cooperative element to move generally widthwise as it swings about said pivot axis.

In this manner, when snaking movement of the towed vehicle occurs, sideways forces on the rear of the towing vehicle will be reduced or "smoothed".

Preferably means is provided to restrain such movement of the first cooperative element about said pivot axis, such as by the use of a manually adjustable friction clutch.

According to this invention there is also provided a towing assembly in accordance with the last preceding paragraph but eight, comprising also features set out in the last preceding paragraph but three.

According to a further aspect of this invention there is provided a towing assembly of the kind specified, wherein either the first cooperative element or the second cooperative element is capable, when its associated part is secured to a vehicle, of limited movement relative to the vehicle either in a vertical direction or in a horizontal direction extending generally widthwise of the vehicle, such as arcuate movement about a generally vertical axis.

There will now be given a detail description, to be read with reference to the accompanying drawings, of a towing assembly which is a preferred embodiment of this invention, having been selected for the purposes of illustrating the invention by way of example.

In the accompanying drawings: FIGURE 1 is a vertical sectional view of the preferred embodiment; FIGURE 2 is a plan view of a first mounting device of the embodiment; FIGURE 3 is a plan view of a second mounting device of the embodiment; FIGURE 4 is a vertical sectional view of the second mounting device; and FIGURE 5 is a view showing a modified construction of first mounting device.

The towing assembly which is the preferred embodiment of this invention is specifically for the towing of caravans, comprising a first part (Figure 1) adapted to be secured rigidly to the towing vehicle, and a second part (not shown) adapted to be secured to the towed vehicle. In the preferred embodiment the invention has been shown as being applied to the first part of the towing assembly, this being intended for use with a second part, which is in itself of conventional construction. It is however to be appreciated that the principles incorporated in the first part may, either individually or in combination, be in additional or alternatively utilised in the second part of the towing assembly.

Thus the first part of the towing assembly comprises a frame element 6 adapted to be bolted to the rear of a towing vehicle in a conventional manner, and a towing element in the form of a ball 8, connected to the frame element 6 through the intermediary of a first mounting device 10 (seel also Figure 2) and a second mounting device 12 (see also Figure 3).

The first mounting device comprises a rear plate 14 mounted for movement parallel to the front plate 6 through the intermediary of a four-bar linkage mechanism 16, the movement of the rear plate 14 being illustrated in chain dotted lines in Figure 1. Mounted between the four-bar linkage mechanism is pressure means 18, comprising a fluid-operated piston/cylinder device 19, and a spring 20, adapted to urge the rear plate 14 into its centralised position against the action of forces applied thereto during the use of the assembly.

The second mounting device 12 comprises a housing 22 adapted to be secured to the rear mounting plate 14 by bolts 24, the housing being provided with a cylinderical bore 26 through which a vertical shaft 28 extends.

Secured to the underside of the housing 28, over the shaft 26, is an end cap 30 carrying a friction plate assembly 32, the pressure exerted by which being adjustable by the use of a lock nut 34.

When secured to the first mounting device 10, the bore 26 of the second mounting device extends vertically, and extending from the shaft 28 is a transverse bar 36, which carries at its outer end portion the ball element 8.

Thus the ball element 8 is permitted to move in a direction generally widthwise of the vehicle, by virture of the freedom of the shaft 28 to rotate within the bore 26 about the vertical pivot axis constituted thereby. The freedom with which the ball element 8 is permitted to move in such an arcuate manner may be restrained to a desired amount by selective tightening of the lock nut 34, and increasing the pressure on the friction plates 32.

In the use of the device which is the preferred embodiment of the invention, the socket of a conventional towing hitch is mounted over the ball element 8, and secured thereto in a conventional manner, in which the two elements are free to partake of relative rotational movement, but are restrained against relative separative movement.

In the operation of the device, in the event that the towed vehicle is subjected to bounce, the vertical loading applied to the element 8 will be absorbed in part by the damping assembly 18, and will tend to reduce the vertical shock loading which otherwise would have been applied to the rear of the towing vehicle.

In addition, should the towing vehicle be subjected to "snake" motion, the capability of the towing element 8 to move in a direction generally widthwise of the line of travel reduces the shock widthwise loading which otherwise would have been applied to the rear of the towing vehicle.

As is apparent from Figure 3, the degree of movement of the towing element 8 in the widthwise direction is limited by the engagement of the arm 36 with shoulders 42 provided in the housing 22. Thus, the degree of permissible movement in the widthwise direction may be selcted as is desirable, by the positioning of the shoulders 42, and the length of the arm 36.

On a termination of any snaking movement of the towed vehicle, the arm 36 will re-adopt a centralised position by virtue of the normal towing action: if desired, means may be provided to restrain pivotal movement of the towing element about the axis of the shaft 28, as may be advantageous when reversing the towed vehicle. A convenient manner of effecting this would be the provision of two vertical bores on either side of the shaft 36 when in its central position, together with the use of an inverted U-shaped element which may be inserted into said bores, to hold the arm in a central position.

In the modified construction of the first mounting device, shown in Figure 4, the same principle is utilised as is described and shown in Figures 1 and 2, other than the piston/cylinder device 18a has been extended beyond the lower pivot mounting of the front plate 6a, in order to reduce the effective height of the front mounting plate.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

I. A towing assembly of the kind specified, wherein at least one of the cooperative elements is mounted in a manner whereby it may undergo limited vertical movement relative to its associated frame element.
2. A towing assembly according to Claim I wherein the first cooperative element is connected to the towing vehicle through the intermediary of a device permitting such vertical movement.
3. A towing assembly according to Claim 2 wherein the device comprises a four-bar linkage.
4. A towing assembly according to any one of the preceding claims wherein the second cooperative element is connected to the towed vehicle through the intermediary of a device permitting such vertical movement.
5. A towing assembly according to Claim 4 wherein said device comprises a four-bar linkage.
6. A device according to any one of the preceding claims comprising means to urge said one cooperative element relative to its associated frame element into an optimum position.
7. A towing assembly according to Claim 6 wherein said means comprises a spring-urged fluid piston/cylinder device.
8. A towing assembly of the kind specified, wherein at least one of the cooperative elements is mounted in a manner whereby it may undergo limited movement in a direction generally widthwise of the vehicle to which it is secured.
9. A towing assembly according to Claim 8 wherein the first cooperative element is connected to the towing vehicle by a pivot mechanism having a vertical axis, the first cooperative element being spaced longitudinally from the axis of the pivot, allowing the first cooperative element to move generally widthwise as it swings about said pivot axis.
10. A towing assembly according to one of Claims 8 and 9 comprising means to restrain such movement of the first cooperative element about said pivot axis.
I I. A towing assembly according to Claim 10 wherein said means comprises a friction clutch.
12. A towing assembly in accordance with any one of Claims I to 8, comprising features according to any one of Claims 8 to 11.
13. A towing assembly of the kind specified, wherein either the first cooperative element or the second cooperative element is capable, when its associated part is secured to a vehicle, of limited movement relative to the vehicle either in a vertical direction or in a horizontal direction extending generally widthwise of the vehicle.
14. A towing assembly according to Claim 13 wherein said movement in a horizontal direction extending generally widthwise of the vehicle is arcuate movement about a generally vertical axis.
IS. A towing assembly constructed and arranged substantially as hereinbefore described, (a) with reference to Figures I to 4, or (b) as modified by Figure 5 of the accompanying drawings.
16. Any novel feature or novel combination of features as hereinbefore described and/or as shown in the accompanying drawings.