GB2220394A - Vehicle trailer for a heavy goods towing vehicle - Google Patents

Abstract

A vehicle trailer for a towing vehicle has sets of wheels (7, 9) mounted on respective axles (8, 10), which are moveable towards and away from one another in the longitudinal direction of the trailer, the axles being mounted on longitudinally- slidable sub-frames (11, 12). The construction is such as to facilitate handling of the trailer when it is being propelled backwards, this being achieved by arranging for the sets of wheels to be closer to one another than when the trailer is being hauled on a highway. Means are provided selectively to lock the sub-frames in position and selectively to brake the wheels of individual axles. <IMAGE>

Description

VESICLE TRAILER FOR A HEAVY GOODS TOWING VEHICLE This invention relates to a vehicle trailer for a heavy goods towing vehicle (truck).

According to the present invention, there is provided a vehicle trailer for a towing vehicle, the trailer having sets of wheels and at least one of the sets being movable towards and away from the other in the longitudinal direction of the trailer.

Preferably, there are two sets of wheels and both are movable towards and away from one another in the longitudinal direction of the trailer.

The construction is such as to facilitate handling of the trailer when it is being propelled backwards, this being achieved by arranging for the sets of wheels to be closer to one another than when the trailer is being hauled on a highway.

Each set of wheels may comprise at least two wheels mounted on a common, transverse axle of the trailer. The trailer may be a two-axle trailer.

Each set of wheels may be mounted on a sub-frame which is slidably mounted longitudinally of a main frame of the trailer.

Each set of wheels can be seLectively locked in position at a forward or rearward location of the trailer, respectively, or at respective locations which are towards the centre of the trailer and the wheelsets can be unlocked from these locations. In addition, each set of wheels can be individually braked so that one set of wheels can be moved longitudinally of the trailer towards or away from the centre of the trailer independently of the other set of wheels.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a side view of a vehicle trailer for a towing vehicle, and Figure 2 is a plan view of the vehicle trailer shown in Figure 1.

Referring to the drawings, the trailer illustrated is a two-axle, turntable-steering, drawbar trailer for a towing vehicle and includes a drawbar 1 with an eye 1A and may be a traditional "" frame drawbar. The drawbar 1 is pivoted to a subframe 4 which supports a turntable 2 which is mounted on ball bearings on a main frame 3 of the trailer. By means of the a pivot 1B and turntable 2, the drawbar 1 is able to swing in a substantially horizontal plane to facilitate tractor unit coupling when the towing vehicle and the trailer are not aligned with the towing jaw of the towing vehicle before connection. Once connected to the towing vehicle, the drawbar 1 will swing to a straight-ahead position and lock automatically by a lock 1C during the first manoeuvring operation.The drawbar 1 can also be arranged to be extensible in a longitudinal direction to allow greater clearance between the towing vehicle and the trailer if found necessary.

Provision is made for locking the turntable 2 in position and this is depicted as a central swing stop 5 which is operated from the towing vehicle. Other means could be provided for locking the turntable, for example upright pins. The subframe 4 also provides bracket support for hydraulic rams 6 which are so connected and arranged to be able to lock the drawbar 1 in position, for example, rigidly in a horizontal attitude, also to raise and lower the drawbar or to allow it freely to pivot during normal road operation.

The trailer shown in-the drawings has two sets of wheels, viz. a front set of wheels 7 mounted on a front axle 8 and a rear set of wheels 9 mounted on a rear axle 10.

Each set of wheels is arranged to be longitudinally slidable with respect to the main frame 3 of the trailer and this is achieved by mounting each axle on a sliding subfrae. The axle 8 is mounted on a subframe 11 beneath the turntable 2 and the axle 10 is mounted under a subframe 12. Each subframe 11, 12 is slidable longitudinally of the trailer from a respective outer end thereof to respective locations towards the centre of the trailer. In this way, it will be seen that the wheelbase can be adjusted, the innermost locations, i.e. the narrowest wheelbase being indicated by the sets of wheels, etc. shown in dotted lines in the drawings.

To lock the subframe 11 in its forwardmost position, two horizontal spigots 13 are provided at the forward end of the subframe 11 and transverse locking pins 14 at the rear end of the subframe 11. The locking pins can be actuated by air or hydraulically so as releasably to engage or disengage the subframe 11 with the main structure of the trailer. To facilitate sliding of the subframe 11, rollers 15 are incorporated in the assembly.

The subframe 11 is able to slide in a slide 16 which is continued to the rear of the main frame 3 of the trailer.

The sliding subframe 12 is substantially identical to the front assembly, it being located in its rearmost position by transverse locking pins 17, corresponding to the transverse locking pins 14, and spigots 18 at the rear of the subframe 12.

Towards the centre of the trailer is a spigot assembly 19 with a pair of forwardly-pointing spigots 20 and a pair of rearwardly-pointing spigots 21. The spigot assembly 19 serves to locate both the front and rear subframes 11, 12 when they are moved to their closed-together position as indicated in dotted lines in the drawings.

The intention of the trailer construction described above is that, when the sets of wheels are farthest apart from one another, the longitudinal stability and roll stability of a convention drawbar trailer is retained for on-road operation. When, however, the wheelsets are closed together, reverse handling of the trailer is eased, in particular when reversing the trailer along a narrow track with relatively tight turns to a load/off-load area off the highway.

It is the intention that the construction be operated by a system comprising electrical circuits, hydraulics and air or any desired combination of motive force and the towing vehicle and trailer will be provided with a system of sequentially-operated locks and releases to allow the axles to be closed or opened from controls in the towing vehicle, so eliminating the need for the driver to leave the towing vehicle cab during the operation other than to uncouple the towing vehicle from the trailer. The locking pins employed in the system described are spring-loaded and rest in matched bush housings to prevent racking and are designed to fail in a safe condition to prevent the trailer from being put out of action before repair can be effected. In addition, each set of wheels is able to be individually braked so as to allow one subframe 11 or 12 to slide longitudinally of the trailer towards or away from the other set of wheels, the set of wheels of the sliding subframe therefore being braked whilst the other set of wheels is unbraked. In practice, it is the trailer main frame 3 which slides relatively to the subframes.

A possible operating sequence would be as follows.

With remote controls in the towing vehicle cab controlling valves and solenoids at the trailer, an actuating button can first be used to lock the turntable 2 to prevent it from turning from a straight-ahead position and maybe also to illuminate a safety light which could be arranged that, until it is illuminated, other procedures cannot be activated. Three other switch positions in the cab could be coded "Front axle", "Rear axle" and "Drawbar".

To close the axles 8 and 10 from their normal, wide wheelbase running condition, the trailer would be drawn forward to align the trailer turntable 2 into the straight-ahead position and then the actuating button is pressed to cause the safety light to illuminate. The turntable 2 is locked by the central swing stop 5.

The "Front axle" switch is pressed, which applies the brakes to prevent the set of wheels 7 from moving, leaving the set of wheels 9 free to move. At the same time, the transverse locking pins 14 are withdrawn to release the coupling between the subframe 11 and the subframe 4.

The trailer is then drawn forwards which causes the trailer frame 3 to slide over the front axle subframe 11 until it fully engages with the spigots 20 towards the centre of the trailer The locking pins 14 are located in such a position that, being spring-loaded and automatically tripped, they subsequently engage with holes 19 in the front of the front subframe 11, thereby to lock the subframe 11 in position near the centre of the trailer.

The "Rear axle" switch is then pressed and this applies the brakes to prevent the rear set of wheels 9 fror.

moving and the transverse locking pins 17 are withdrawn.

The "Front axle" switch is then switched off, which will release the brakes to allow the front set of wheels 7 to move.

The trailer is then reversed to cause the frame 3 to slide over the rear axle subframe 12 to bring the subframe 12 towards the centre of the trailer to engage with the spigots 21 and the locking pins 17, which are also located to engage in the other end of the subframe 12.

Once this has been achieved, the "Rear axle" switch is switched off, the "Drawbar" switch is switched on the this causes all the brakes to be released and the drawbar to be locked into a rigid, horizontal condition.

The trailer is now ready to be reversed into the required area for loading or unloading, with the two sets of wheels forming a comparatively narrow wheelbase for the trailer. The spigot assembly 19 is designed to resist tyre scrub stresses when the trailer is being reversed around corners.

To return the axles to the normal running position, the sequence is as follows.

Firstly, the "Drawbar" switch is switched off, the "Front axle" switch is switched on and then the trailer is reversed until the front axle subframe 11 is fully engaged in its forwardmost position, the wheels 7 having been prevented from moving whilst the wheels 9 are abc to move.

Then the "Rear axle" switch is switched on and the "Front axle" switch is switched off and the trailer is drawn forwards with the wheels 9 being prevented from moving and the wheels 7 being free to move. Thus, the action of drawing the trailer forwards causes the trailer to ride over the stationary rear subframe 12 until the subframe 12 is engaged in its rearmost position. The "Rear axle" switch is then switched off and the primary actuating button is cancelled, which releases the turntable lock and extinguishes the safety light.

In this condition, the trailer is ready to be driven away with the wheelsets at their wide wheelbase spacing for normal operational activity on the highway.

Claims (9)

CLAIMS:

1. A vehicle trailer for a towing vehicle, the trailer having sets of wheels and at least one of the sets being moveable towards and away from the other in the longitudinal direction of the trailer.

2. A vehicle trailer according to claim 1, wherein there are two sets of wheels and both are moveable towards and away from one another in the longitudinal direction of the trailer.

3. A vehicle trailer according to claim 1 or 2, wherein each set of wheels comprises at least two wheels mounted on a common, transverse axle of the trailer.

4. A vehicle trailer according to claim 1, 2 or 3, wherein the or each set of wheels is mounted on a subframe which is slidably mounted longitudinally of a main frame of the trailer.

5. A vehicle trailer according to any one of the preceding claims, wherein each set of wheels is selectively lockable in position at a forward or rearward location of the trailer, respectively, or at respective locations which are towards the centre of the trailer and the wheel sets can be unlocked from these locations.

6. A vehicle trailer according to any one of the preceding claims, wherein each set of wheels is individually braked.

7. A vehicle trailer according to any one of the preceding claims and including apparatus to control and actuate movement of said at least one set of wheels towards and away from the other in the longitudinal direction of the trailer.

8. A vehicle trailer according to any one of the preceding claims and being such that, when it is being propelled in a backwards direction, the sets of wheels are closer to one another than when the trailer is being hauled in a forwards direction.

9. A vehicle trailer for a towing vehicle, substantially as hereinbefore described with reference to the accompanying drawings.