Abstract: A master cylinder includes a hydraulic pressure control valve having a valve member mounted in a valve body and normally held apart from a valve seat by a valve spring. The valve member is seated on the valve seat when a pressure in a pressure chamber of a housing of the master cylinder reaches a predetermined level. A control device includes a body received in the bore and having one end portion of a convex shape. The body of the control device is urged by a spring in such a manner that the one end portion projects through a port of the housing into the pressure chamber.

Abstract: A master cylinder reservoir includes a cylindrical body having an open upper end. A cap is fitted on and removably secured to the body, the cap engaging the open end of the body at a lower end portion thereof. The cap has a mounting portion formed adjacent to the lower end portion thereof. The mounting portion defines together with the upper surface of the open end of the body a circumferential space. The mounting portion has a first surface disposed in opposed spaced relation to the upper surface of the open end of the body. The mounting portion has a second surface disposed in opposed relation to the outer surface of the upper end of the body. The outer surface of the upper end is spaced from the second surface adjacent to the upper surface of the body to form a circumferential recess. A diaphragm received in the cap and having a peripheral portion received in the circumferential space and held between the first surface of the mounting portion and the upper surface of the open end of the body.