| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize a cost reduction by improving a constitution of a cap and a body in a brake master cylinder. SOLUTION: In the brake master cylinder, a first pressure chamber R1 is communicated with a reservoir connection port 11b at a retreat position of a first piston 31 through a piston port 31a, a first communication passage (communication groove 26a1) and a second communication passage (annular groove 12d, communication hole 12e) provided on a cap 12. An annular seal member (seal cup) 15 is assembled to the cap 12 and sealingly seals a space between the cap 12 and the piston 31 at a rear side of a guide 26. A flange portion 12g extending to an inner diameter direction rather than an outer diameter direction of the seal member 15 and restricting a retreat movement of the guide 26 by an abutment to a rear end of the guide 26 is provided on the cap 12 between the annular seal member 15 and the guide 26.</p> |
