| 摘要 |
A cylinder portion (13) formed in a caliper (12) supports a pressure receiving portion (16a) and a pressing portion (16b) of a piston (16) so as to allow the pressure receiving portion (16a) and the pressing section (16b) to advance and retreat. The piston (16) is provided with a retraction mechanism (20). The retraction mechanism (20) includes a reversing member (21) for generating a reversing force when compressed by the pressure receiving portion (16a) and the pressing portion (16b). The mechanism (20) further includes a movable element (22) moved in a retreating stroke due to the reversing force, and a first elastic member (23) for generating a restoring force and imparting the restoring force, the first elastic member (23) generating the restoring force when compressed by the movable element (22) and the pressure receiving portion (16a) which is moved in an advancing stroke. The mechanism (20) further includes a second elastic member (24) for generating a frictional force for maintaining the compression and deformation of the first elastic member. The reversing member (21) generates the reversing force along with the advance of the pressure receiving portion (16a), the movable element (22) relatively retreats due to the reversing force and compresses the first elastic member (23), and the generated restoring force returns the pressure receiving portion (16a) and the pressing portion (16b) along with a decrease in pressure of a brake fluid. |
