| 摘要 |
A servo-assisted master cylinder assembly for a vehicle hydraulic braking system has a tandem master cylinder with primary and secondary pistons operative to pressurise primary and secondary pressure spaces for primary and secondary brake circuits. A servo chamber is defined behind the primary piston, and pressurisation of the servo chamber from a source of pressure fluid is controlled by a valve in response to an input force applied to the primary piston. The valve comprises a spool operated solely by pressure in the primary space and a bias force from servo pressure in a bias chamber and a spring. The secondary piston has a smaller effective area than the primary piston, so that the pistons are in abutment in their retracted positions. To reduce pedal travel, one of the brakes of the primary circuit can be supplied from the servo chamber instead of the primary pressure space. |
