Master cylinder

A master cylinder comprising:

• a cylinder body;
• a piston which is slidably provided in a cylinder hole formed in the cylinder body;
• a pressure generating chamber defined between said piston and said cylinder body;
• a fluid passage which connects said pressure generating chamber to a reservoir for supplementing hydraulic fluid to said pressure generating chamber;
• a cylindrical connecting portion that is integrally formed with said reservoir and is fitted within a connecting receiving portion of the cylinder body, with said cylindrical connecting portion including an end face that defines a valve seat, wherein said fluid passage extends at least through said cylindrical connecting portion;
• an output port through which the hydraulic fluid is pumped from said pressure generating chamber when said piston operates;
• a throttle passage formed in said fluid passage for throttling flow of the hydraulic fluid to the reservoir from said pressure generating chamber when said piston operates;
• and
• a throttle valve mechanism provided in said fluid passage for allowing hydraulic fluid to bypass said throttle passage and flow to said pressure generating chamber from said reservoir by opening a valve when a fluid pressure in said pressure generating chamber becomes lower than a pressure in said reservoir, said valve of said throttle valve mechanism including said valve seat and an at least generally plate-shaped, floating valve body, wherein said valve body moves into engagement with said valve seat in response to a flow of the hydraulic fluid that is caused by operation of said piston, and said valve body moves away from said valve seat in response to a flow of the hydraulic fluid that is caused by the fluid pressure in said pressure generating chamber becoming lower than the pressure in said reservoir.