| 摘要 |
PURPOSE:To improve durability of a rolling diaphragm by making the thickness of an arc shaped outer wall of the rolling diaphragm thicker than the thickness of a straight outer wall, and avoiding the occurrence of the fracture in an arc shaped rolling part even though a tensile force is acted in the circumferential direction. CONSTITUTION:The thickness of the arc shaped outer wall 13 of an rolling diaphragm 11, which separates the inside of a booster shell 1 into a first front actuating chamber A and a second rear actuating chamber B, is made thicker the thickness of the straight outer wall 12. When a booster piston 6 is advanced, the arc shaped rolling part R2 is rolled, and the part of a point (a) is contacted with an inner surface of a booster shell 1 as shown by a point (a'). Therefore the tensile force is acted on the arc shaped rolling part R2 in the circumferential direction. Since the thickness of the arc shaped outer wall is made thick, the arc shaped rolling part R2 is not fractured. |
