To eliminate the insufficient feeling of braking, caused by the variation of regenerative braking force, by a small and inexpensive means.
The spring 28 of a relief valve 26 is installed between a valve element 27 and a control piston 31, and an adding spring 32 is installed, which makes the piston 31 position on a first position (where the force of the spring 28 is made into a normal depression action value) at the time of brakeless operation. The fluid pressure of wheel brakes 17 and 18 makes the piston 31 operate so that the piston 31 can be displaced against the spring 32, to displace the piston 31 from the first position to a second position, where the force of the spring 28 can be made about zero when fluid pressure of a master cylinder 22 crosses a given value to be increased.
ENOMOTO NAOYASU
ANDO MASAKI
