| 摘要 |
A master cylinder includes a housing defining a reservoir and a bore for movably receiving a pair of pistons. A primary piston cooperates with a secondary piston to define a primary chamber therebetween and cooperates with the housing to substantially define an auxiliary chamber. The primary chamber and auxiliary chamber are disposed within a substantially uniform diameter section of the housing bore. The primary piston is movable within the bore to communicate fluid pressure from the auxiliary chamber to the primary chamber until a predetermined pressure level is reached in the primary chamber whereupon the auxiliary chamber is vented to the reservoir. A sealing member disposed within a recess on the bore cooperates with the piston to define the auxiliary chamber. Upon initial movement of the piston relative to the sealing member, a small portion of the fluid within the auxiliary chamber is communicated to the reservoir so as to bleed the auxiliary chamber. Further movement of the piston relative to the sealing member closes the auxiliary chamber to the reservoir and communicates pressurized fluid from the auxiliary chamber to the primary chamber. The sealing member is disposed within a recess on the wall of the housing bore and the recess leads to an opening communicating with the reservoir.
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