This invention relates to bearing assemblies and, more particularly, though not exclusively, to a bearing assembly for a brake actuating shaft for a vehicle axle.

An axle, for example for a trailer vehicle, comprises an axle beam having a hub at each end. The hubs are rotatably mounted on bearings and, adjacent to each hub, there is a brake assembly. Each brake assembly comprises a brake anchor bracket secured to the axle beam, as by welding or bolting, and carrying two opposed brake shoes which are pivotally mounted at one end on anchor pins and at the other end bear on a ' brake actuating mechanism. The brake actuating mechanism comprises a shaft (the camshaft) having a cam on its outboard end and which is spaced from and lies parallel to the axle beam, rotatably mounted in an outboard bearing assembly at the anchor bracket and in an inboard bearing assembly adjacent to the inboard end of the camshaft. The inboard bearing assembly is mounted on the axle beam. One end of a lever is fitted to the camshaft at its inboard end and the other end of the lever is connected to a brake actuator, operated, for example, by compressed air, to rotate the camshaft to cause the brake shoes to be expanded to engage a brake drum' carried by the hub. Expansion of the brake shoes is effected by the cam, for example an S-cam, on the outboard end of the camshaft which acts on the other ends of the brake shoes via rollers mounted thereon.

This invention provides a novel bearing assembly which, inter alia, may be used as the outboard bearing for the camshaft on an axle such as has been described.

According to a first aspect of the present invention a bearing assembly comprises in combination a bush having a cylindrical bore and a part-spherical outer periphery, and opposed housing members secured, or adapted to be secured, together having inner surfaces shaped to co-operate with the outer periphery of the bush so as to hold and locate the bush whilst allowing tilting of the bush within the assembled housing members, at least one of the housing members being formed to provide for axial and radial location of the assembly on or in a mounting therefor and the bore of the bush having an annulus adapted to receive a locating member such that a shaft having a peripheral annulus and entered into the bush may be located axially in the bearing assembly by a locating member engaged between the two annuli.

The locating member may be a snap ring or spring clip to facilitate assembly of the shaft in the bearing assembly and removal therefrom.

In applications in which the bearing assembly is required to react a radial force applied to the shaft (such as is the case when the shaft is an S-cam brake shaft) it may be beneficial to provide for the radial location of the bearing assembly by one or more, preferably three egui-spaced, protrusions on one of the housing members adapted to locate radially against a surface or surfaces of the mounting for the assembly radially spaced from the central axis of the cylindrical bore, such that a proportion of the radial force is transmitted to the mounting through the protrusion, or one of the protrusions.

According to a second aspect of the present invention there is provided in combination a bearing

assembly in accordance with the first aspect of the invention as herein set forth and a shaft having a peripheral annulus and entered into the cylindrical bore of the bush, said shaft being located axially in the bearing assembly by a locating member engaged between the annulus of the bush and the annulus of the shaft.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a front elevation of a bearing assembly and a shaft, the latter being shown in section,

Figure 2 is a side elevation of the bearing assembly and shaft of Figure 1 , showing the bearing assembly in section,

Figure 3 is a front elevation of a snap ring,

Figure 4 is a plan view of the snap ring of Figure 3, and

Figure 5 is a scrap view in enlarged detail of part of Figure 2 showing a bearing surface of a housing member which co-operates with a bush of the bearing assembly.

Referring to Figures 1 and 2 of the drawings, a bearing assembly 1 includes two housing members which are shown as similar- steel pressings 2, 3. The pressings each have an outer flange portion 4 with registering holes 5 whereby the assembly 1 can be secured, for example by bolts or like fastenings, to a

mounting which is here shown (in part only) in Figure 2 as a brake anchor bracket 6. Inboard from the flange portions 4 the pressings 2, 3 have an axially extending portion which includes three equi-spaced protrusions 7 joined by and alternating with three part-spherical portions 8. The protrusions 7 and portions 8 merge to extend axially a short distance and then radially inwardly to provide housings for O-ring seals 9.

A bearing bush 11 has a cylindrical bore 11* and a part-spherical outer periphery 12 which co-operates with the complemerntary part-εpherical portions 8 of the pressings 2, 3 which provide axial and radial location, and support, for the bush. The bush 11 has centrally located radial lubrication passages 14, provided as drillings, extending from its outer periphery 12 into a central annulus 15, which is in the form of a groove as seen in Figure 2. A shaft 16 is received in the bush 11.

The pressings 2, 3 each incorporate a small platform 17. The platform 17 of pressing 2 is drilled and tapped to receive a grease nipple 18 for injection of grease to lubricate the co-operating surfaces of the part-spherical portions 8 of the pressings and the outer periphery 12 of the bush 11 and, via the lubrication passages 14 and annulus 15, the co-operating surfaces of the bush 11 and shaft 16.

T e shaft 16 also has an annulus 19 in the form of a groove (shown as being of U-shaped cross-section but it may for example be of V-shaped cross-section) and a snap ring 21 is engaged ^' in the annuli 15, 19 to locate the shaft 16 in the bearing assembly 1. As seen in Figures 3 and 4 the snap ring 21 is generally oval in shape and, Figure 2, of circular cross-section, and

provides a satisfactory location for the shaft 16. The application of a blow with a hammer to the end of the shaft is sufficient to release the snap ring 21 from the annulus 19 and allow removal of the shaft 16.

In an S-cam brake, rotation of the shaft 16 to expand the brake shoes against the brake drum gives rise to a bending force on the shaft, applied at the cam. Preferably the bearing assembly and its mounting are arranged so that a proportion of this bending force is reacted by the mounting through one of the protrusions 7. An axle such as has been described will have an S-cam brake at each end, one having a left hand cam and the other a right hand cam. Considering the bearing assembly as shown in Figures 1 and 2, the three equi-spaced protrusions 7 of the pressing 3 adjacent to the anchor bracket 6 locate in and abut radially against the peripheral wall surface 6 * of an opening in the anchor bracket through which the shaft 16 extends. When a bending force is exerted on the shaft at the cams a proportion of the bending force for the right hand camshaft will be reacted at the relevant bearing assembly by one of the three protrusions 7 of the one pressing 3 at the appropriate location bearing radially on the respective anchor bracket at the peripheral wall surface 6' of the opening, and a proportion of the bending force for the left hand camshaft will be reacted at the relevant bearing assembly by a protrusion 7 of its one pressing bearing radially at another of the locations on the anchor bracket with which that bearing assembly is associated.

The protrusions 7 centralise and radially locate the bearing assembly in the anchor bracket 6. Also, the flanges 4 locate the bearing assembly axially with respect to the anchor bracket 6.

For transport purposes the bearing assembly may be made by staking the pressings 2, 3, and the assembly is secured for use by bolting to a mounting.

The bush 11 may conveniently be made of sintered metal or of a plastics material. The housing members have been described as metal pressings. However, these also could be of sintered metal or of a plastics material. In the latter case the part-spherical housing for the bush, whether of sintered metal or of plastics material, may be continuous instead of the interrupted design provided by the spaced part-spherical portions 8 of the pressed members which have been described. Similarly, the protrusions 7 may be continuous instead of being interrupted.

Figure 5 is a scrap view on an enlarged scale showing a part-spherical bearing surface of the pressing 3 which co-operates with the outer periphery 12 of the bush 11, as seen at the top right of Figure 2.