| 摘要 |
<p>Pneumatic brake servo comprising within a shell-shaped casing (10), a piston (22) delimiting, in conjunction with a rolling diaphragm (18), a front chamber (26) permanently connected to a low pressure source and a rear chamber (28) selectively connected to the front chamber (26) or to a high pressure source by at least one valve means (62, 58a, 70a). Said valve means is actuated by a control rod (38) disposed in the brake booster's axis of symmetry (X, X') and is capable of engaging, through the front face (36) of a plunger, the first surface of a reaction disk (37) integral with the second face of a thrust rod (35). Said valve means (62, 58a, 70a) is controlled by a transfer key (44) integral with the plunger (36) and includes a valve element (62) co-operating with a first valve seat (58a) formed on the piston (22) and a second valve seat (70a) formed on a valve piston (98) integral with the transfer key (44). According to the invention, the valve means (62, 58a, 70a) is entirely disposed in an enclosure (54) formed on the piston (22).</p> |
