| 摘要 |
PROBLEM TO BE SOLVED: To minimize the change to an assisting means and ensure a proper input and output characteristic even in the failure of the assisting means and even after the assisting limit. SOLUTION: An auxiliary piston 20 having a major diameter part larger than the effective sectional area of a master piston 12 and a minor diameter part smaller than the sectional area is arranged in the rear of the master piston so as to form a first pressure transmission chamber R3 between the major diameter part and the master piston and a second pressure transmission chamber R4 between the minor diameter part and the master piston, and be capable of interlocking with the operation of the assisting means. When the master piston is assisted through the auxiliary piston, the first pressure transmission chamber is sealed by a first valve means comprising a valve element 25 and the like, and the second pressure transmission chamber is also sealed by a second valve means comprising a valve element 21 and the like after the second pressure transmission chamber internally reaches a prescribed pressure. When the assisting is not performed, the first and second pressure transmission chambers are allowed to communicate with a reservoir 4. |
