Fluid pressure control device

A fluid pressure control device comprising a housing having an input port connected to a fluid pressure supply source, an output port leading to a fluid pressure operated device and a release port connected to a reservoir;

• a sliding member slidably fitted in said housing between a retracted position, at which position said sliding member connects said output port with said release port, and an advanced position at which position said sliding member connects said output port with said input port;
• a reaction chamber in said housing and facing a front surface of said sliding member for generating a fluid pressure urging said sliding member in a retracting direction, said reaction chamber being connected to said output port;
• an urging piston slidably fitted in said housing and operatively connected to a rear end of said sliding member;
• an input piston slidably fitted in said housing and operatively connected to an operation member;
• and a pressure chamber formed between a back surface of said urging piston and a front surface of said input piston;
• wherein a pressure receiving area A1 of said sliding member, exposed to said reaction chamber, is set smaller than a pressure receiving area A2 of said urging piston, exposed to said pressure chamber, and said pressure receiving area A2 of said urging piston is set smaller than a pressure receiving area A3 of said input piston exposed to said pressure chamber, and wherein said pressure receiving areas A1, A2 and A3 are in such a relationship that A2/A1>A3/A2.