IES970615A2 - Tram lining device - Google Patents

Abstract

A tram lining device comprises a telescopic tow bar (21) having at one end a hitch (30) for connecting the front end of the tow bar to the rear of a towing vehicle (10) and at the other end a plate (28) for connecting the rear end of the tow bar to a trailer (14). Stablilising arms (36), one on either side of the tow bar (21), constrain the tow bar to pivot substantially only in a vertical plane relative to the vehicle, and a hinge (29) between the plate (28) and the tow bar allows the trailer (14) to pivot side-to-side relative the tow bar.<Fig.1>

Description

This invention relates to a device, referred to herein as a tram lining device, which can be incorporated in or retrofitted to the chassis of a wheeled trailer to be towed by a vehicle, typically a tractor, to allow the wheels of the trailer to follow the path of the wheels of the vehicle when the tractor is on a linear or non-linear pathway.

According to the invention there is provided a tram lining device comprising a tow bar preferably of adjustable length, first means for connecting one end of the tow bar to a towing vehicle such that the tow bar can pivot substantially only in a vertical plane relative to the vehicle, and second means for connecting the other end of the tow bar to the front of a trailer so that the trailer can pivot side-to-side relative the tow bar.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic plan view of a trailer coupled to a tractor using a tram lining device according to the invention, Figure 2 is a side view of the tram lining device of Figure 1, Figure 3 is a perspective view of the tram lining device of Figure 1, and Figure 4 shows the stabilising arms and collar of the tram lining device of Figure 1. 8970615 Figure 1 is a schematic plan view a tractor 10 having a pair of front wheels 11 and a pair of rear wheels 12.

The rear wheels 12 are joined by a transverse axle 13 and have an axis of rotation A. A trailer 14 has a body 15 which rests on a chassis 16. A pair of wheels 17, which support the chassis 16, are mounted on a transverse axle 18 for rotation about an axis B.

Conventionally, a trailer is hitched to a hitch point at the rear of the tractor via a hitch which projects forwardly from the chassis. In such a case, the wheels of the trailer will not follow the path of the rear wheels of the tractor when the tractor traverses a non-linear pathway. Therefore, to allow the wheels of the trailer 14 to follow the path of the wheels of the tractor 10 when the tractor is going around a corner or curve, the tractor 10 is in the present case coupled to the trailer 14 by a tram lining device generally indicated at 20.

The device 20 includes a tow bar 21 having front and rear parts 22 and 23 respectively of square cross-section, the front part 22 being telescoped within the rear part 23 to allow the overall length of the tow bar 21 to be adjusted. The front part 22 of the tow bar has a series of apertures 24 along each vertical sidewall, each aligned with a corresponding aperture 24 in the opposite sidewall, and the rear part 23 of the tow bar has a single pair of aligned apertures 25, one in each vertical sidewall. A particular overall length of tow bar is selected by inserting a bolt 26 through the apertures 25 and a selected pair of the apertures 24 .

An adaptor plate 28 is pivotally connected by a hinge 29 to the rear end of the tow bar 21. In use of the device 20 the plate 28 is bolted to the front of the trailer 8*70015 chassis 16 with the axis of the hinge 29 substantially vertical to permit the trailer to pivot from side to side relative to the tow bar. A conventional hitch 30 projects from the front end of the tow bar 21 for connection to the hitch point 32 on the tractor.

A rectangular collar 34 is slidably mounted on the front part 22 of the tow bar, and a pair of upper and lower flanges 35 project from each opposite vertical sidewall of the collar 34. A pair of stabilising arms 36 are provided one on each side of the collar 34, each arm 36 having its rear end connected to a respective ball joint 37 mounted between the flanges 31 on its side of the collar 34.

In use, the front ends 38 of the stabilising arms 36 are connected to the rear end of the tractor 10, at locations laterally spaced one on either side of the hitch point 32, to confine the tow bar 21 to pivot substantially only in a vertical plane relative to the tractor 10. The slidable collar 34 allows some choice as to the precise locations on the rear of the tractor to which the ends 38 of the arms 36 are attached, by permitting the ends 38 to be connected at locations closer or wider apart as desired.

Furthermore, to accommodate for undulating ground, it is vital that the collar 34 be slidable relative to the front part 22. In the very unlikely event where the ground is substantially level or at least not subject to significant undulations, the collar 34 may, if desired, be fixed fast to the front part 22. Also, if the hitch 30 is positioned a distance higher than shown (for example, if an additional more elevated tow hitch was provided on the tractor 10), the collar 34 would not need to be slidable relative to the front part 22 and may be fixed thereto It will be seen that the overall length of the tow bar 21 can be adjusted so that the distance between the axis of the hinge 29 and the axis A is substantially the same as the distance between the axis of the hinge 29 and the axis B. Thus, when the tractor 10 turns while towing the trailer 14, the wheels 17 of the trailer will follow the tracks of the rear wheels 12 of the tractor. If desired, the collar 34 may be omitted and instead, the ball joint 37, or other suitable connection of each arm 36 may be in slidable inter-engagement with a respective u-shaped projection (not shown) mounted on each side of the front part 22.

A significant advantage of the invention is that the hitch 30 may be connected to the conventional draw hitch on the tractor 10 and is not dependent on the lifting arms of the tractor 10. By providing a telescopically adjustable tow bar 21, variations in the location, either forwardly or rearwardly, of the tow hitch of the tractor 10 may be easily accommodated.

The invention is not limited by or to the embodiment described herein which may be modified or varied without departing from the scope of the invention.

Claims (5)

1. A tram lining device comprising a tow bar preferably of adjustable length, first means for connecting one end 5 of the tow bar to a towing vehicle such that the tow bar can pivot substantially only in a vertical plane relative to the vehicle, and second means for connecting the other end of the tow bar to the front of a trailer so that the trailer can pivot side-to-side relative the 10 tow bar.

2. A tram lining device as claimed in claim 1, wherein the first means comprises a hitch at the said one end of the tow bar for attachment to a tractor hitch point and 15 two stabilising arms each having one end connectable to the tow bar and the other end connectable to a point on the tractor laterally spaced from the hitch point.

3. A tram lining device as claimed in claim 2, wherein 20 a collar is slidably mounted on the tow bar, and wherein the said one ends of the stabilising arms are pivotally connected to respective opposite sides of the collar.

4. A tram lining device as claimed in any of claims 25 1-3, wherein the tow bar comprises a plurality of parts telescoped together.

5. A tram lining device substantially as hereinbefore as described with reference to and as illustrated in the 30 accompanying drawings.