GB2200875A

GB2200875A - Dual wheel assembly

Info

Publication number: GB2200875A
Application number: GB08703235A
Authority: GB
Inventors: Sir Neville Bowman-Shaw
Original assignee: Lancer Boss Ltd
Current assignee: Lancer Boss Ltd
Priority date: 1987-02-12
Filing date: 1987-02-12
Publication date: 1988-08-17
Also published as: GB8703235D0

Abstract

The wheel assembly comprises an inner wheel 1 and an outer wheel 2 mounted on a wheel hub 3 of a vehicle, the outer wheel 2 frictionally engaging a mounting ring 6 fixed to the hub to enable slip in rotation relative thereto under excessive loads during tight turning of the vehicle. An annular bearing block 7 is welded to the inside of the outer wheel and has a frustoconical surface 8 which frictionally engages a frustoconical surface 9 on the ring 6. The slipping of the outer wheel reduces tyre scrub during turning. <IMAGE>

Description

WHEEL ASSEMBLY The invention relates to a wheel assembly and in particular to an assembly of two driven wheels which are adapted to be mounted together on one side of a steered vehicle.

In heavy vehicles and vehicles designed to carry heavy loads it is normal practice for single wheels to be replaced by multiple wheel assemblies, such as two wheels mounted coaxially and rigidly fixed to one another.

Such assemblies are provided at either end of the drive axle of trucks which are steered by their non-driven wheels. The advantage of replacing one wheel by two coaxial wheels is that wheels of reduced size can be used to carry the same loads.

When a vehicle of this type is being turned, the centre of the vehicles turning circle will generally lie in line with the driven axle, but spaced outboard of the vehicle. In vehicles having a very tight turning circle, such as load handling vehicles, the centre of the turning circle on full lock will lie relatively close to the vehicle, and where coaxial wheels are employed in pairs, the difference between the turning circles of the inner and outer wheels of the pair of wheels nearer to the centre of turning can be significant. This results in tyre scrub which causes excessive wear of tyres especially where heavy loads and tight turning circles are combined. The problem of tyre scrub is naturally not so serious on the opposite pair of wheels where the difference in their turning circles is proportionally far less significant.

The 'inner wheel' and 'outer wheel' as used herein refer to the relative positions of the wheels on the vehicle.

The present invention provides a wheel assembly in which the problem of scrub is reduced by virtue of the outer wheel of a pair being able to slip in rotation relative to the inner wheel.

According to the invention there is provided a wheel assembly comprising an inner wheel adapted to be rigidly mounted on a wheel hub of a vehicle, an outer wheel adapted to be mounted on the hub coaxially with the inner wheel, and mounting means for mounting the outer wheel on the hub such that the outer wheel is normally driven in rotation with the hub and the inner wheel but can slip in rotation relative thereto under excessive loads.

Embodiments of the invention are described below with reference to the accompanying drawings in which: FIGURE 1 shows a diagrammatic section, through part of a wheel assembly; and FIGURE 2 shows a similar view through an alternative embodiment.

The tyres of the assembly are partially shown in phantom. The assembly comprises an inner wheel 1 and an outer wheel 2 mounted on a wheel hub 3 of a vehicle (not shown).

The inner wheel is mounted as usual by means of its flange 4 directly onto the hub by means of studs 5. A mounting ring 6 for the outer wheel is also mounted on the studs 5.

An annular bearing block 7 is welded to the inside of the outer weel-and has a frusto-conical surface 8 which frictionally engages with a frusto-conical surface 9 on the ring 6 over a frusto-conical interface.

The surfaces 8 and 9 are urged into engagement by clamping ring 10 which fits loosely onto corresponding studs 11 extending axially from a radial flange 12 of the mounting ring 6. The clamping ring 10 is tightened against the bearing block 7 by means of nuts 13 and Belleville washers 14 and thereby urge the surfaces 8 and 9 axially into engagement. A bead 15 is formed on the flange 12 such that the clamping ring may rock to maintain pressure on the block 7. The single ring 10 shown in the drawings could be replaced by a plurality of separate rings corresponding to the -number of studs 11.

The pressure acting between the surfaces 8 and 9 can be adjusted by means of the nuts 13 such that the outer wheel can be set up to slip relative to the inner wheel when the torsional load therebetween exceeds a predetermined level. In this way the assembly can be set up in a manner such that drive is transmitted through both wheels under normal conditions but which allows the outer wheel to slip during very tight turning where the outer wheel is nearer to the centre of the turning circle of the vehicle.

In the alternative embodiment shown in Figure 2, the outer wheel is carried on a mounting ring 16 which is supported on the hub by means of studs 5 and a spacing ring 17. A friction ring 18 disposed between the inner cylindrical surface of the wheel 2 and the outer cylindrical surface of the mounting ring transmits drive between the two under normal conditions but allows slippage under heavy loads during tight turns.

In this embodiment, the web of the outer wheel is reinforced by the provision of a ring 19, which may not be continuous, welded thereto and the wheel is held axially in position on the mounting ring 16 by a clamping ring 10 thightened against the end face of the mounting ring 16 by nuts 13 and lock washers 14. Shims (not shown) are provided between the clamping ring 10 and the end face of the mounting ring to adjust the axial clamping force applied to the outer wheel 2.

Claims

1. A wheel assembly comprising an inner wheel adapted to be rigidly mounted on a wheel hub of a vehicle, an outer wheel adapted to be mounted on the hub coaxially with the inner wheel, and mounting means for mounting the outer wheel on the hub such that the outer wheel is normally driven in rotation with the hub and the inner wheel but can slip in rotation relative thereto under excessive loads.

2. A wheel. assembly as claimed in claim 1 wherein the mounting means comprises a mounting ring adapted to be mounted on the wheel hub and wherein the outer wheel is mounted on the mounting ring by fixing means which urge the outer wheel axially into frictional engagement with the mounting ring.

3. A wheel assembly as claimed in claim 2 wherein the outer wheel and the mounting ring engage over a frusto-conical interface.

4. A wheel assembly as claimed in claim 1 wherein the mounting means comprises a mounting ring adapted to be mounted on the wheel hub and having an outer cylindrical surface; wherein the mounting means further comprises a friction ring disposed between the inner cylindrical surface of the outer wheel and the outer cylindrical surface of the mounting ring.

5. A wheel assembly substantially as described herein with reference to the accompanying drawings.