GB2245235A

GB2245235A - A trailer having a steerable wheel with adjustable castor angle to aid reversing

Info

Publication number: GB2245235A
Application number: GB9109863A
Authority: GB
Inventors: Thomas Walter Hill
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-06-21
Filing date: 1991-05-08
Publication date: 1992-01-02
Anticipated expiration: 2011-05-08
Also published as: GB2245235B; GB9109863D0; GB9013897D0

Abstract

A trailer has a frame (1) which is pivoted to the lowing vehicle about a horizontal axis. To the rear it has a single road wheel (10) mounted on a leg (9) pivotally carried at the base of a member (5). This member can be rotated about a vertical axis by wires (7) linked to the towing vehicle, thus steering the trailer. The leg (9) can be swung between a forward mode position, where it inclines down and rearwardly, and a reverse mode position, where it inclines down and forwardly. Spring (12) and lever operated means (13, 14) or power operated means (14, 15, 16) may be provided to effect the changeover. <IMAGE>

Description

Improvements relatinq to Trailers" This invention relates to trailers for road vehicles.

Conventionally, such trailers are connected by a single hitch point and normally they have two wheels on a common axle. However, when reversing, for example to dump a load, they are difficult to steer.

It is the aim of this invention to provide a vehicle trailer which is much more controllable when reversing.

According to the present invention there is provided a trailer for road vehicles comprising a frame adapted for hinged connection about a generally horizontal first axis transverse and to the rear of a towing vehicle, an element pivoted to the rear of the frame about a second axis parallel to the first axis, a single road wheel carried by said element, and means for adjusting said element between a forward and a reverse mode when the wheel axis is respectively to the rear of and forward of said second axis.

Conveniently, this wheel is steerable and a member carried by the frame and to which said element is pivoted may be rotatable about a generally vertical axis, the steering being effected through control of this member.

There may be means for connecting the wheel to the steering mechanism of the towing vehicle so that the wheel can be turned in synchronism.

Said element may be spring biased to said forward mode and the adjusting means may include a lever-operated Bowden cable by which the element can be changed over against the spring bias to said rearward mode.

Alternatively, the adjusting means may include a power operated jack.

For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawing in which the single figure is a side elevation of a vehicle trailer. The load carrying platform or bucket is omitted for simplicity.

The trailer has a main frame 1 which may be of generally iscoceles triangular form, apex to the rear. At its forward end, at the corners of the triangle, there are eyes 2 for pivotal connection to the rear of a vehicle, which will allow the frame 1 to swing up and down, but not from side to side.

Towards the rear of the frame 1 there is an upright tubular housing 3 which receives a shaft 4 which forms the stem of an inverted T-shape member 5. The arms 6 of this member have wires 7 attached to their ends which lead forwards below the towing vehicle, where they may be coupled to the latter's steering mechanism. Underneath the arms 6 the member 5 is briefly extended and has a lateral stud 8 with a horizontal axis which carries a leg 9. A road wheel 10 is mounted at the free end of the leg, which can be swung from the full line position about the stud 8 to the dotted line position. It is in the full line position for forward motion and is transferred to the dotted line position for rearward motion.

The changeover can be achieved in various ways. In one arrangement, the leg 9 has a crossbar 11 transverse to the axis of the wheel 10 secured near its upper end and a tension spring 12 acts between one end of this bar 11 and the rear end of the frame 1 to urge the wheel to the forward mode position. The other end of the bar is coupled via a wire 13 of a Bowden cable 14 to a lever in the towing vehicle. This lever can be pulled to switch over the wheel position and then locked to keep it in the reverse mode.

When released the spring will help the wheel 10 return to the forward mode. The spring 12 and wire 13 will not materially interfere with the steering of the wheel, which is effected by the wires 7.

In an alternative arrangement, shown in broken lines, a power unit 14 mounted on the frame 1 operates a screw 15 through a universal joint 16. The screw engages in a nut secured to the rear end of the bar 11. As the power unit is energised so the screw 15 is turned to swing the wheel 10 between the reverse and forward modes. Steering can still be carried out, this being allowed by the universal joint 16.

Claims

1. A trailer for road vehicles comprising a frame adapted for hinged connection about a generally horizontal first axis transverse and to the rear of a towing vehicle, an element pivoted to the rear of the frame about a second axis parallel to the first axis, a single road wheel carried by said element, and means for adjusting said element between a forward and reverse mode when the wheel axis is respectively to the rear of and forward of said second axis.

2. A trailer as claimed in Claim 1, wherein the wheel is steerable.

3. A trailer as claimed in Claim 2, wherein the member to which said element is pivoted is rotatable about a generally vertical axis and the steering of the wheel is effected through control of this member.

4. A trailer as claimed in Claim 2 or 3, wherein there are means for linking the wheel to the steering mechanism of the towing vehicle, whereby the wheel is turned in synchronism.

5. A trailer as claimed in any preceding Claim, wherein the sub-frame is spring biased to said forward mode.

6. A trailer as claimed in Claim 5, wherein said adjusting means includes a lever-operated Bowden cable by which the sub-frame can be changed over against the spring bias to said rearward mode.

7. A trailer as claimed in any one of Claims 1 to 4, wherein said adjusting means include a power-operated jack.

8. A trailer for road vehicles substantially as hereinbefore described with reference to the accompanying drawing.