| 摘要 |
In a two-stage reaction device for vacuum brake boosters, the clearance at the piston rod will be reduced by the piston rod acting directly on the valve piston which comprises a head portion connected via a neck portion at its end close to the vacuum chamber. The head portion and the rear end surface of the valve piston contain abutment surfaces which cooperate with levers. The levers, in turn, are moved by the push rod coupled to the master cylinder via a fork-like shaped pressure member with prong-shaped attachments. In this arrangement, one end of each lever is held resiliently between a supporting ring and a spring plate, with the supporting ring including edges about which the levers are tiltable when the pressure member acts on the other ends of the levers. The tilting movement of the lever takes place abruptly and only in the area between the two abutment surfaces at the valve piston and at the valve piston's head portion, respectively, while the two facing ends of the levers are in constant abutment on one of the two abutment surfaces and the two radially outwardly disposed ends of the levers abut on the supporting ring.
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