摘要 |
A vacuum servo unit includes a constant pressure chamber and a variable pressure chamber in a housing, a power piston, an output member, an input member, a plunger, a valve mechanism, and an actuator. The actuator is disposed in the power piston for moving the plunger in the forward and rearward directions. The outer periphery of the actuator is provided with a concave or recessed portion serving as a communicating passage between the constant pressure chamber and the variable pressure chamber. The concave or recessed portion is in the form of a notch defined in a yoke enclosing the solenoid coil of the actuator. The communicating passage is constituted by the notch and the inner periphery of a cylindrical portion of the power piston at the front side of the power piston.
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