GB2194205A - Towing stabiliser - Google Patents

Abstract

This invention relates to a stabilising device for a caravan, trailer or the like when being towed by a motor vehicle. A stabilising device 10 includes a friction damper device 12 which comprises a first member 14 fixed to the rear of the vehicle, and a second member 16 rotatable with respect to the first member and being rigidly connected to one end of a spring bar 24. The other end of the spring bar is in use located in a bracket 28 attached to an extension of the caravan chassis and a friction member 42 is located between the first and second members to oppose motion therebetween and thereby retard oscillation of the caravan. The damping device includes a cam mechanism 34 adjustable from a first, open position in which the resistance between the two members is low and the spring bar is easily movable, to a second, locked position in which the resistance between the two members is high and the device acts to damp oscillation of the caravan. <IMAGE>

Description

SPECIFICATION Improvements in stabilizing devices This invention relates to stabilising devices, and more particularly relates to a stabilising device for a caravan or trailer when being towed by a motor vehicle.

When a caravan is travelling along the open road it can quite easily be set in oscillation due to the effects of crosswinds or slipstreams created by large vehicles. Obviously this can cause havoc for the driver of the towing vehicle and can even result in the caravan overturning and causing a serious accident. In order to alleviate this problem caravan stabilising devices are available which tend to damp the oscillation of the caravan. An example of such a stabilising device is disclosed in UK Patent No. 1277879 (Scott). The Scott device comprises a bracket connected to the rear of the towing vehicle which has an outer cylindrical member fixed thereto. An inner cylindrical member is housed inside the outer cylindrical member and has one end of a spring bar attached to the bottom thereof.

The other end of the spring bar is able to be placed in a bracket fixed to the extended chassis of the caravan. Oscillation of the caravan causes rotation of the inner cylindrical member with respect to the outer cylindrical member, and a friction liner located between the two cylindrical members opposes this rotation and hence quells oscillation of the caravan fairly quickly. However, one problem encountered with caravan stabilising devices such as the one described above is that a substantial amount of strength is required to lift the spring bar and place it in the bracket due to the resistance offered by the friction liner. In fact the task is almost impossible for many women, old or weak people and can cause injury to even a strong and fit person.

It is intended that the present invention should overcome or reduce the above disadvantages.

According to the present invention- there is provided a stabilising device for a caravan, trailer or the like towed by a motor vehicle comprising a motion damping device connected to the rear of the motor vehicle, said damping device comprising a first member fixed to the rear of the vehicle, a second member rotatable with respect to the first member and being rigidly connected to one end of a spring bar, the other end of said spring bar in use being located in a bracket attached to an extension of the caravan chassis, a friction member located between the first and second members to oppose motion therebetween and thereby retard oscillation of the caravan, characterised in that the damping device includes a cam mechanism adjustable from a first, open position in which the resistance between the two members is low and the spring bar is easily movable, to a second, locked position in which the resistance between the two members is high and the device acts to damp oscillation of the caravan.

Preferably the cam mechanism includes a bolt which extends through the two members, and spring-loading means.

A locking nut is preferably attached to the end of the bolt underneath the first and second members and the tightness of the locking nut determines the degree of damping.

Preferably the spring-loading means comprise a plurality of disc springs located adjacent the two members, said disc springs being of a resilient material enabling the cam mechanism to change from its open to its locked position and retaining the cam in either position.

A hardened cam is preferably pivotally attached to the top of the bolt and is able to move through approximately 90" to effect locking and unlocking of the mechanism.

Preferably a hardened steel washer and a collar are on the bolt between the disc springs and the cam to act as a wear surface.

The invention will be described, by way of example, with reference to and as illustrated in the accompanying drawings, in which: Figure 1 is an exploded view of a device in accordance with the invention; and Figure 2 is a view showing the device in its locked position.

Referring to the drawings, a caravan stabillising device 10 includes a friction damper unit 12 which comprises a first member 14 and a second member 16. The first member 14 has an integral arm 18 and is thereby fixed to the rear of the towing vehicle by means of plate 20 and screw 22. The second member 16 consists of an upper and a lower plate, said upper and said lower plates being located above and below the first member 14 respectively, and being secured to a spring bar 24 by means of bolts 26. The spring bar 24 is downwardly curved and the other end thereof is, in use, located in an L-shaped bracket 28 which is fixed to the chassis of the caravan (not shown). A centre bolt 30 extends through both first and second members 14, 16 and spring bar 24 and is secured by a locking nut 32 underneath said spring bar.

The tightness of the locking nut dictates the level of damping. A hardened cam 34 is pivotally attached to the top end of the bolt 30 and is able to move from a first, open position in which the longitudinal axis of the cam is vertical to a second, locked position in which the longitudinal axis of the cam is horizontal. The cam is able to be moved from one position to the other by means of a tommy bar (not shown) inserted in the orifice 35. A plurality, in this case 3, of flexible disc springs 36 is located on top of the damper unit 12 and the bolt 30 extends through the centre of these springs. A collar 38 and harded steel washer 40 are also positioned on the bolt 30 as can be clearly seen in Fig. 1. A friction liner 42 is located between the first and second members 14, 16.When the cam 34 is in its open position, the length of bolt available for the disc springs, collar and washer is longer than when the cam is in its locked position. In the locked position the shorter available length of bolt results in compression of the flexible disc springs.

In use of the device, the cam 34 is placed in its open position. This ensures that the disc springs are not compressed and therefore no force is exerted on the friction damper unit.

Therefore the friction liner 42 will offer little frictional resistance to the motion of the second member 16 relative to the first member 14. The spring bar 24 can then be lifted and placed in the bracket 28 on the caravan chassis with ease. The cam is then rotated to its locked position thereby compressing the disc springs and exerting force on the damper unit.

Due to this applied force the friction liner 42 will tend to oppose any relative motion between the two members 14, 16. Therefore when the caravan is subjected to any oscillatory motion, the device will tend to damp these oscillations in the normal way.

A distinct advantage of the invention is that it enables a stabilising device to be attached to-a caravan with ease. The cam mechanism may also be sold as a kit so that it can be fitted to existing stabilising devices.

Claims (8)

1. A stabilising device for a caravan, trailer or the like towed by a motor vehicle comprising a motion damping device connected to the rear of the motor vehicle, said damping device comprising a first member fixed to the rear of the vehicle, a second member rotatable with respect to the first member and being rigidly connected to one end of a spring bar, the other end of said spring bar in use being located in a bracket attached to an extension of the caravan chassis, a friction member located between the first and second members to oppose motion therebetween and thereby retard oscillation of the caravan, characterised in that the damping device includes a cam mechanism adjustable from a first, open position in which the resistance between the two members is low and the spring bar is easily movable, to a second, locked position in which the resistance between the two members is high and the device acts to damp oscillation of the caravan.

2. A stabilising device as claimed in claim 1 in which the cam mechanism includes a bolt which extends through the two members, and spring loading means.

3. A stabilising device as claimed in claim 2 in which the spring loading means comprise a plurality of disc springs located adjacent the two members, said disc springs being of a resilient material enabling the cam mechanism to change from its open to its locked position and retaining the cam in either position.

4. A stabilising device as claimed in any of claims 1 to 3 wherein a locking nut is attached to the end of the bolt underneath the first and second members and the tightness of the locking nut determines the degree of damping.

5. A stabilising device according to any of the preceding claims wherein a hardened cam is pivotally attached to the top of the bolt and is able to move through approximately 90" to effect locking and unlocking of the mechanism.

6. A stabilising device according to any of the preceding claims in which a hardened steel washer and a collar are on the bolt between the disc springs and the cam to act as a wear surface.

7. A stabilising device substantially as herein described with reference to the accompanying drawings.

8. A stabilising device according to claim 1 and substantially as herein described.