Vacuum pump for vehicle brakes - has variable speed drive to maintain constant vacuum at all engine speeds

摘要

The vacuum pump (1) is driven by a shaft (3) with an eccentric (2) on it. The shaft is attached to a disc with a hollow conical surface (5). The disc is driven by friction from a ball (4) in the cone, and the ball is driven by a similar disc on its other side which is driven by a shaft (8) from the engine. The two discs are off centre to each other and the drive ratio depends on the position of the ball between them. The ball is moved by a plunger (7) which is operated by a pneumatic positioner (11) which receives the output vacuum of the pump (1).