| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve a support structure of a second piston disposed at a front side of a first piston in a brake master cylinder. SOLUTION: In the brake master cylinder, a sleeve 23 assembled to a cylinder housing 10 comprising a body 11 and a cap 12 and axially slidably supporting both pistons 31, 32 by an inner hole 23c has a communication passage (communication groove 23e, communication hole 23i) for communicating a first pressure chamber R1 formed between both pistons 31, 32 with a feed-out port 11d provided on the body 11. A seal cup 27 for sealingly sealing a space between the second piston 32 and the sleeve 23 is assembled to an annular groove 23g provided on an inner periphery of the sleeve 23. A communication hole 23j is provided on a cup retaining wall 23k for slidably guiding the second piston 32 in an axial direction and restricting a rearward movement of a seal cup 27. The annular groove 23g and the feed-out port 11d are communicated by the communication hole 23j.</p> |
