| 摘要 |
PCT No. PCT/FR92/01020 Sec. 371 Date May 4, 1993 Sec. 102(e) Date May 4, 1993 PCT Filed Nov. 4, 1992 PCT Pub. No. WO93/11012 PCT Pub. Date Jun. 10, 1993.The invention relates to a pneumatic brake-booster comprising a casing (10) inside which is a piston formed by a hub (20) and by a skirt (14) and which, with the aid of an unrolling membrane (12), defines a front chamber (16) permanently connected to a partial vacuum source and a back chamber (18) connected selectively to the front chamber (16) when a first valve passage (56, 58) is opened or to the atmosphere when a second valve passage (76, 78) is opened, the first and second valve passages (56, 58; 76, 78) being formed by first valve means (58, 78) co-operating with second valve means (56, 76), and being actuated by a control rod (35) capable of bearing, through the intermediary of a plunger (32), against one of the faces of a reaction disk (42) securely attached to a push rod (44). According to the invention, the first valve means (58, 78) are formed on the hub (20) of the piston.
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