| 摘要 |
PCT No. PCT/FR94/00023 Sec. 371 Date Jul. 31, 1995 Sec. 102(e) Date Jul. 31, 1995 PCT Filed Jan. 7, 1994 PCT Pub. No. WO94/18042 PCT Pub. Date Aug. 18, 1994A pneumatic booster having a casing (16) formed from a cylinder (32) and a cover (34). The casing (16) is divided into two chambers (18,20) by a movable wall (10). The movable wall. (20) has a plate (12) and a flexible membrane (14). A bead (30) on the outer peripheral edge of flexible membrane (14) is fixed to the casing (16). The flexible membrane (14) forms a fold in a space located between the peripheral edge of the plate (12) and the casing (16). The plate (12) is secured to a hub structure which houses a valve member for operating the pneumatic booster. The plate (12) which is substantially parallel to the end cover has an extension (40) that extends in a forward direction substantially concentric to the cylinder (32). The extension (40) has front part (46) and a rear part (44) with a radial shoulder (42) on the front part. The radial distance (D) between the rear part (44) and the cover (34) is substantially equal to the radial distance between the front cover part (46) and the cylinder (20) minus the thickness of the membrane (14). Thus the movable wall (10) defines a maximum active surface for the development of an operational force in response to the development of a pressure differential upon actuation of the valve member.
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