GB2324073A

GB2324073A - Liner for articulated vehicle couplings

Info

Publication number: GB2324073A
Application number: GB9801557A
Authority: GB
Inventors: John Smith
Original assignee: OMEGA HOLDINGS Ltd
Current assignee: OMEGA HOLDINGS Ltd
Priority date: 1997-01-25
Filing date: 1998-01-26
Publication date: 1998-10-14
Also published as: GB9801557D0

Abstract

A low friction liner 1 is provided for the rotational coupling between the tractor unit and trailer of an articulated vehicle. The liner 1 comprises a self-lubricating plastics material, preferably a polyurethane elastomer loaded with graphite, bonded by adhesive to the coupling plate 2 of the tractor unit (or to the coupling plate 5 of the trailer).

Description

LINER FOR ARTICULATED VEHICLE COUPLINGS This invention relates to an anti-friction liner for use in the rotational coupling between the tractor and trailer of an articulated vehicle.

The rotational coupling of an articulated vehicle is commonly referred to as the "Fifth Wheel". The coupling part on the tractor unit is pivoted to allow vertical and horizontal movement, thus allowing the vehicle combination to corner and turn. It usually consists of a roughly circular plate (fifth wheel plate) with a 'V' shaped notch in its rearward side and some kind of bolt or claw lock arrangement at its centre. The coupling part of the trailer comprises a pin which engages with the lock to couple the trailer to the tractor unit: the trailer's weight is carried on the surface of the fifth wheel plate.

The fifth wheel plate is usually made from pressed steel or a casting and carries heavy loads. As a result friction and wear can be significant if these parts are not correctly lubricated. Normal practice is to smear grease on the coupling plate so that tractor and trailer can rotate or articulate freely relative to one another. A dry coupling will result in high friction forces sufficient to seriously affect the handling of the vehicle. Unfortunately in dry, dirty, dusty or gritty conditions the grease collects substantial quantities of foreign matter and may be reduced to an abrasive paste which, if left, may damage the coupling beyond repair.

Regular maintenance involving thorough cleaning and replacement grease is difficult to enforce and in any event results in the use of substantial quantities of expensive grease: furthermore, its effectiveness may be limited by connection of the tractor unit to a contaminated trailer.

In accordance with the present invention, there is provided a low friction liner for the rotational coupling between the tractor unit and trailer of an articulated vehicle, the liner comprising a self-lubricating plastics material.

Preferably the liner comprises a polyurethane elastomer which is loaded with graphite, to provide the self-lubrication.

Preferably the liner is, in use, bonded by adhesive to the coupling plate of the tractor unit, or to the corresponding plate of the trailer.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIGURE 1 is a schematic plan view of a tractor unit with a liner in accordance with the present invention fitted to the fifth wheel coupling plate; and FIGURE 2 is a side elevation of the tractor unit having a trailer coupled to it.

Referring to the drawings, a liner 1 is bonded onto the coupling plate 2 of the tractor unit. The liner 1 has a Vshaped notch to match the coupling plate 2. In the example shown, the trailing legs of the liner (either side of its notch) terminate at a point 3 at or slightly beyond the top of the ramp section 4 of the coupling plate 2, to avoid damage as the tractor unit is reversed under the trailer (at which time the tractor coupling plate may not be aligned ideally).

Instead, however, the trailing legs of the liner may extend down the ramp section 4 of the coupling plate 2.

The liner 1 comprises a flat piece of polyurethane elastomer loaded with graphite and therefore self-lubricating.

The liner 1 is bonded to the coupling plate 2 but it may also be riveted to the coupling plate, particularly at its leading and/or trailing edges. Instead, the liner may be bonded to the coupling plate 5 of the trailer unit.

We have found that the liner 1, being made of a polyurethane elastomer, has good tear resistance, exceptionally good resistance to wear and (being elastomeric) good shapememory. Further, polyurethane elastomer has a low coefficient of friction and the graphite with which it is loaded provides self-lubrication.

The polyurethane elastomer is produced by casting onto a flat bed, such that the top surface (whilst very flat) is not as flat and does not have such a shiny finish as the bottom surface. In fitting the liner, the fifth wheel coupling plate is cleaned, preferably steam cleaned) to remove all traces of dirt and grease and the liner is chemically cleaned on the shiny flat side, before the application of adhesive for bonding the liner to the coupling plate. By bonding the liner in position, the likelihood is reduced that the edge of the liner will be caught as the coupling plates of the tractor unit and trailer interengage.

Claims

1) A low friction liner for the rotational coupling between the tractor unit and trailer of an articulated vehicle, the liner comprising a self-lubricating plastics material.

2) A liner as claimed in claim 1, in which said plastics material comprises a polyurethane elastomer loaded with a lubricating material.

3) A liner as claimed in claim 2, in which said lubricating material comprises graphite.

4) A liner as claimed in any preceding claim when fitted to the rotational coupling between the tractor unit and trailer of an articulated vehicle, the liner being bonded by adhesive to the coupling plate of the tractor unit or of the trailer.

5) A low friction liner substantially as herein described with reference to the accompanying drawings.