| 摘要 |
PROBLEM TO BE SOLVED: To provide a master cylinder capable of improving supply performance of a brake fluid.SOLUTION: A piston seal 45 disposed in a peripheral groove 32 comprises: an annular base part 101; an inner peripheral lip part 102 projecting from an inner peripheral side of the base part 101; an outer peripheral lip part 103 projecting from an outer peripheral side of the base part 101; and an intermediate projecting part 104 projecting from a space between the inner peripheral lip part 102 and the outer peripheral lip part 103 of the base part 101. On a wall face 89A on a supply path 48 side of the peripheral groove 32, a step part 93 which becomes hollow with respect to a face part 89a on a bottom face 88A side is formed on an opening side of the peripheral groove 32. The step part 93 extends into a range of thickness in a radial direction of the intermediate projecting part 104 of the piston seal 45, and is formed into an annular shape. |
