To provide a miniature and inexpensive decompressing means variable in decompression quantity.
The spring 28 of a relief valve 26 is installed between a valve element 27 and a control piston 31, for making the decompression quantity of the relief valve 26 variable. The control piston 31 is pushed in a direction for closing the valve element 27 via a spring 28, by the pressure difference between a control fluid pressure chamber 32 and wheel brakes 17 and 18. The pressure difference action area for the control piston 31 is set slightly larger than that of the valve element 27. A control fluid pressure lead in path 33 for leading control fluid pressure into a control fluid pressure chamber 32 from a master cylinder 22, and an opening/closing solenoid valve 34 for increasing control fluid pressure, normally opened, for opening/closing the control fluid pressure lead in path 33, are installed.
SAKAI TOSHIYUKI
ANDO MASAKI
