| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of component items, to simplify the structure, to reduce the cost and the size, and to obtain a large braking force by boosting the master cylinder pressure as necessary. SOLUTION: This master cylinder 3 is provided with a primary piston 12 and a propulsion piston 13 in a housing 11, and a booster chamber 23 is formed on a rear side of the propulsion piston 13. An end part on the front side of an input shaft 14 is located within the booster chamber 23. A communication passage 13a (a discharge passage 28) is formed in the propulsion piston 13, and a control valve 26 to open/close the communication passage 13a (discharge passage 28) from the propulsion piston 13 and the end on the front side of the input shaft 14 is provided. When the input shaft 14 is advanced from the non-operational condition indicated in the figure, a pump 27 is operated, and the discharge pressure of the pump 27 is introduced in the booster chamber 23, the fluid pressure is generated in the booster chamber 23, the primary piston 12 is advanced by this fluid pressure, and the fluid pressure is generated in a fluid pressure chamber 16.
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