| 摘要 |
A spool 10 adapted to change over a communicated state between an output port 8, input ports 6a, 6b and a release port 7 in dependence on an axial displacement thereof is slidably fitted in a housing 5. The input ports 6a, 6b lead to the hydraulic pressure supply source Sa, Sb, the output port 8 leads to the braking unit B, and the release port 7 leads to an oil tank T. The actuator 11, adapted to generate a thrust force in dependence on an amount of electricity inputted thereinto is operatively connected to one ends of the spool and a hydraulic pressure chamber 15 leading to the output port 8 is formed in the housing 5 to generate hydraulic force adapted to counteract against the thrust force since it is exposed to the other end face of the spool 10. The spool is provided with a shaft portion 20 extending in an oil tight manner through a valve housing 5. A chamber leading to the tank T is formed between a stepped spool portion, adjacent the shaft portion, and the housing 5. <IMAGE> |
