Brake control for four-wheel drive transmission - has equalising gear drive to lock front and rear drives during braking

摘要

The brake control for a four wheel drive vehicle has the front and rear drives locked together during braking to prevent rear wheel instability. It enables the rear brakes to be increased in size, and relieves the front brakes of thermal loading. The rigid coupling is achieved by either blocking the differential between the front and rear wheel drives, or by providing the rear drive differential with a locking clutch. The differential (40) between the front and rear wheel drives is provided with a multi-plate clutch (58) operated by a hydraulic servo-cylinder (74) linked to the brake circuit. The plates are operated by a thrust sleeve (68) sliding over the drive shaft.