摘要 |
An automatic brake booster includes a solenoid and a solenoid plunger which allow a flow path in a valve mechanism to be switched without depression of a brake pedal. The solenoid plunger comprises a rear member on which an atmosphere valve seat is formed, a front member which is disposed to be displaceable with respect to the rear member, and a first spring disposed between the both members. When a current fed to the solenoid is less than a given value, the first spring remains inactive while when the current exceeds the given value, the first spring becomes flexed to reduce a clearance between the rear member and a holder which forms part of a magnetic path of the solenoid together with the rear member. When the booster operates as an automatic brake, a gentle brake operation which allows a precise control with a reduced brake output and a quick brake operation with an increased brake output can be simultaneously achieved in a preferred manner.
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