Reaction transmitting mechanism of brake booster

A reaction transmitting mechanism for brake booster which comprises a valve mechanism responsive to a back-and-forth movement of a valve plunger mechanically coupled to an input shaft to exercise a controlling action upon opening or closing a flow path of a pressure fluid, an output shaft having its one end slidably fitted in a valve body in which the valve mechanism is received, a reaction disc interposed between the said one end of the output shaft and the valve plunger, and an annular reaction transmitting member reciprocably mounted on the valve body and interposed between the reaction disc and the valve plunger, the annular reaction transmitting member being arranged such that upon actuating a brake, the inner periphery of the reaction transmitting member engages the valve plunger to transmit a reaction from the reaction disc to the valve plunger while upon releasing the brake, the outer periphery of the reaction transmitting member engages the valve body to transmit a reaction from the reaction disc to the valve body;

• the reaction transmitting mechanism being characterized in that the reaction transmitting member includes a tubular portion engageable with the valve plunger, and a flange-like portion extending radially outward from the end of the tubular portion opposite from the reaction disc and engageable with the valve body, an annular member being disposed over the valve body and including a covering which is interposed between the reaction disc and the flange-like portion of the reaction transmitting member so as to cover the flange-like portion, and a through-opening in which the tubular portion of the reaction transmitting member is slidably fitted.