| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate concentrated deformation in a lip part and to prolong the life of a cup seal by providing a plurality of liquid returning passage openings positioned away from one another in the peripheral direction of a cylinder hole. SOLUTION: A plurality of liquid returning passages 16 for communicating a slave pressure chamber with a hydraulic liquid reservoir are composed of an annular recessed part 40 formed in a cylinder main body 3 and a cylindrical member 15 fitted in the recessed part 40. A plurality of liquid returning grooves 50 are provided in each of the flange parts 46 and 47 of the cylindrical member 15 and each liquid returning groove 50 has a prescribed interval from another in the peripheral direction of a cylinder hole 4 and penetrates each of the flange parts 46 and 47 so as to cross a liquid returning space 48 in the axial direction of a slave piston 8. Thus, although liquid pressure deforms the lip parts 9A and 18A of cup seals 9 and 18 so as to push these into respective liquid throttling holes 60, the pressure is dispersed in the peripheral direction and deforms the lip parts.</p> |
