| 摘要 |
PURPOSE: To prevent the degradation such as corrosion of a switching means caused by being exposed to the air by installing the switching means, connected to a power source and fitted to a power piston, in a constant pressure chamber normally communicated with a vacuum source. CONSTITUTION: In a vacuum type booster, a power piston 10 is axially moved in a housing 2, partitioned into constant pressure chambers 6, 8 and transforming chambers 7, 9, to generate braking force. A plunger member 20 moved through an input member 12 axially moved by brake operation is fittingly mounted in the power piston 10, and a solenoid 17 for actuating the plunger member 20 upon receiving power supply from a power source is also provided in the power piston 10. In this case, a limit switch serving as a switching means put in action by a brake return detecting means 26 including a switching rod when the input member 12 is moved by the specified quantity relatively to the power piston 10 is provided in the constant pressure chamber 8 so as to be protected from corrosion or the like. |
