Abstract: Drive engagement apparatus for engaging a driven gear (18) with a shaft (14) connected to a load. Engagement is achieved by interengaging an axially movable sleeve (19) with a dog. One of the sleeve (19) or dog is drivably connected to the gear (18) and the other to the shaft (14). Compressed air acts on a piston (21) which is engaged via a fork (22) with the sleeve (19) to effect axial movement of the sleeve (19). However, axial movement is delayed by a friction drive, which prevents engagement between the sleeve (19) and dog until the rotational speeds of those elements is equalised. The friction drive is actuated by pressing together a plurality of friction plates (24) using the compressed air. The dog comprises an engagement unit (231) that is interengageable with the sleeve (19) and a base unit (232) that is axially movable under the air supply to activate and deactivate the friction drive.

Abstract: A drive arrangement (1) is disclosed where a driving gear (13) is engageable with a shaft (14) by engaging an axially movable sleeve (19) with a dog (23). One of the sleeve (19) or dog (23) is drivably connected to the gear (13) and the other to the shaft (14). A piston (21) is engaged via fork (22) with the sleeve (19); axial movement of the piston (21) causes axial movement of the sleeve (19). A delay device is included which prevent engagement between the sleeve (19) and dog (23) until the rotational speeds of those elements is equalised. The delay device include a friction plates (24) which create a friction drive between the driving force (e.g. gear (13)) and the element to be driven. The friction drive is actuated by actuator (25) under the same compressed air supply that acts on piston (21). Torque acting between the friction plates (24) and sleeve (19) prevent the sleeve (19) from moving into engagement with the dog (23) before the speeds of the sleeve (19) and dog (23) have equalised.

Abstract: A vehicle road wheel mounting arrangement including a wheel hub with a shoulder against which a wheel center can be secured by a plurality of screwthreaded studs and nuts and, so that the vehicle wheel cannot be stolen even if all the nuts are removed from the screwthreaded studs, the hub having a groove containing a retainer ring and structure for urging the retainer ring radially outwards to make captive the wheel center on the hub.