Hydraulic braking pressure control apparatus

摘要

Hydraulic braking pressure device which includes a casing divided into a first cylinder portion and a second cylinder portion by a partition. A first piston is slidably fitted in the first cylinder portion and defines an input chamber between one end face thereof and the partition which is connectible to an output port of a master cylinder. The opposite end face of the first piston and the end of the first cylinder portion define a control chamber connectible with an anti-lock control mechanism. A second piston is slidable fitted in the second cylindrical portion and defines an output chamber between one end face thereof and the partition which is connectible to a wheel brake. The opposite end face of the second piston and the end of the second cylinder portion define a spring chamber in which a spring is housed biasing the second piston towards the partition. The first and second piston are fitted to both ends of a piston rod which penetrates movably and sealingly through the partition. A valve mechanism is provided in the partition and closes in response to movement of the second piston away from the partition cutting off communication between the input and output chambers. The sectional area of the first piston is smaller than that of the second piston.