Patent ID: 8286427

Claim:
A master cylinder, comprising: a cylinder body including a pressure chamber, into which an operating liquid is introduced from a reservoir; a supply passage for supplying the operating liquid from the reservoir to the pressure chamber; a piston slidably fitted in the cylinder body to define the pressure chamber, the piston adapted to open or close the supply passage according to a sliding position thereof; a bypass passage for bypassing the supply passage to connect the reservoir and the pressure chamber, the bypass passage including a check valve adapted to open to allow a flow of the operating liquid from the reservoir to the pressure chamber when a pressure in the pressure chamber is lower than that in the reservoir, the check valve comprising a lift valve in which a valve body is seated on or moves away from a valve seat, the valve body of the lift valve being disposed in a valve case including the valve seat and a guide portion for slidably guiding the valve body which are formed as a single member; and wherein the valve body includes a sliding portion which slides relative to the guide portion, and a valve portion which is disposed at one side of the sliding portion in a sliding direction and is seated on or moves away from the valve seat; the valve body is urged toward the valve seat by an urging means; the sliding portion of the valve body has a circular outer circumference, and a length of the sliding portion in the sliding direction is set to be longer than a diameter of the sliding portion; and a length of the guide portion in the sliding direction is set to be longer than the length, in the sliding direction, of the sliding portion of the valve body which is guided by the guide portion.