| 摘要 |
PROBLEM TO BE SOLVED: To shorten the whole length of a hydraulic brake device with an inexpensive constitution, in the device for directly driving a master piston by an auxiliary piston when a hydraulic pressure generating source fails. SOLUTION: This device is provided with the hydraulic pressure generating source 4 for generating and outputting prescribed hydraulic pressure, regardless of a brake operation for a brake pedal 2, a pressure regulating valve 6 for regulating the output hydraulic pressure according to brake operating force, a master cylinder for outputting brake hydraulic pressure from a pressure chamber by the master piston 8 operated according to the output hydraulic pressure and the auxiliary piston 600 which is arranged coaxially with the master cylinder 8 and directly drives the master piston 8 according to the brake operation when a hydraulic pressure system fails. A part of at least one of the master piston 8 and the auxiliary piston 600 is constituted to advance into the other and to form an overlapped part. For instance, when at least the master piston 8 is located at an initial position, a cylindrical rear end part of the master piston 8 is constituted to advance into an annular recessed part 615. |
