| 摘要 |
PROBLEM TO BE SOLVED: To control the introduction of the atmosphere into a working chamber in compliance with the operating mode, i.e., normal braking or emergency braking, using a single valve element, and in the condition that the input member is at a standstill, a booster piston is prevented from being actuated by hindering the introduction of the atmosphere into the working chamber even in case an eventual failure energizes the solenoid and actuates the valve element. SOLUTION: A valve element 301 energized by a spring toward the reversing limit is installed on an input member 52 in such a way that the specified stroke can be shifted to the front or rear, and a solenoid 16 of an electromagnetic auxiliary controlling means and a stationary core 18 are fastened to a valve cylinder 10 coupled with booster pistons 4 and 6, and a movable core 21 confronting the stationary core 18 is coupled with the valve element 301 , and an atmosphere shut-off means 62 to block an atmosphere introducing hole when the input member 52 is positioned in the final retreat limit is installed between the input member 52 and a backward extension cylinder 12 of a booster shell. |
