Abstract: A hydraulic pressure cylinder with an integrated reservoir which includes a cylinder body of strengthened resin, a reservoir tank of strengthened resin molded with the cylinder body as one body and having a wall portion and an opening formed in the wall portion of the reservoir tank and having a frame portion defined by the opening, and a window plate formed of resin material soluble in said strengthened resin and having a high transparency characteristic, the window plate including a flange which is welded to an inner surface of a wall portion of a reservoir tank and a projecting part which projects from the flange toward an outer surface of the wall portion of the reservoir tank along the frame portion.

Abstract: A piston for a cylinder device which is formed of fiber glass strengthened resinous material and includes a concave portion, where a plug may remain, formed on an end thereof. The piston is engageable with a push rod and in particular an end surface of the push rod. The concave portion may be formed on approximately the center portion of the end concave surface of the piston and may be of circular configuration. Correspondingly, the concave portion may be formed on a flat surface of the end surface of the piston.

Abstract: A master cylinder of resin material includes a cylinder having a receiving portion within which a piston is sealingly slidable, a cylindrical portion having a diameter which is larger than that of an outer periphery of the cylinder and coaxially rearwardly extending from the fore part of the receiving portion, and mounting flanges radially extending from a rearward end of the cylindrical portion. Each of the cylinder, the cylindrical portion and the mounting flanges are integrally formed.

Abstract: A master cylinder reservoir includes a reservoir cap fixed in an open portion of the reservoir. The master cylinder reservoir comprises a cam portion formed on the periphery of the reservoir in the direction meeting at right angles with the axial center of the reservoir, a nail means formed on the reservoir cap and having tip end bended inside, a guide means formed on the upper end of the cam portion, and a gloove-hole formed between the cam means, and the stop means to thereby receive the tip end of the nail means therein, whereby the movement of the reservoir cap in the circumferential direction and the upper and lower directions will be prevented.

Abstract: In a sealing or piston cup for maintaining lubricating oil on a sealing surface, the sealing surface thereof is formed with a circumferentially extending angular recess or groove which functions to retain lubricating oil. The sealing cup with the recess can ensure a smooth and stable operation of the device.

Abstract: A sealing cup to be used for a hydraulic piston-cylinder device the cup having an outer lip with a leading edge adapted to slide along a wall when fitted in the device. The angle .alpha. of the leading edge with respect to the cylinder axis is made smaller than the angle of a portion other than the leading edge with respect thereto, and is made as 1.degree..ltoreq..alpha..ltoreq.15.degree. in the free condition of the cup. When the sealing cup is installed to be slid in the cylinder, a wedge-shaped clearance is formed between the leading edge and the cylinder wall due to provision of the angle .alpha., thereby admitting the fluid therein to decrease the slide resistance of the sealing cup.