Abstract: An improvement of the inner periphery of a power piston which is connected to a valve body of a booster is disclosed. The inner periphery of the power piston comprises a radial portion which is disposed in abutment against an end face of a step formed on the valve body, an annular groove located radially outward of the radial portion, and a step formed at the boundary between the radial portion and the annular groove. The provision of the annular groove and the step assures sufficient strength around the inner periphery of the power piston without requiring an increased wall thickness of the power piston.

Abstract: A disk brake of a floating caliper type having a disk rotating with a vehicle wheel, a caliper having a hydraulic cylinder mechanism, a support member secured to a stationary portion of a vehicle and a pair of friction pads mounted on the support member. The friction pads supported by the support member through wedge contact and resiliently urged by spring portions of pad clip members so that the friction pads are kept in surface contact with the support member at the time of non-braking. A sufficient area for transmitting the braking forces applied by the friction pads are stably maintained at the time of start of the braking, and the rotation moment on the pads are reduced and the braking forces are dispersedly transmitted to the disk run-in and run-out sides of the support member during the braking.

Abstract: A disc brake has a disc rotor, a pair of confronting friction pad assemblies arranged on both sides of the disc rotor, a pad assembly support member fixed to an automotive vehicle body, and a caliper driving piston for moving one of the friction pad assemblies relative to the other in an axial direction of the disc rotor. The pad assemblies are each provided with a pair of lower two engaging steps for transmitting the brake torques to the support member, and also with upper corner shoulders for transmitting the brake torques. The support member is provided with step portions corresponding to the engaging steps and the upper corner shoulders of the brake assemblies. Thus, it is possible to reduce or suppress a deformation of the brake assemblies when the disc rotor rotates upon the brake application.

Abstract: Construction of a seal arrangement for a sliding part of a pin slide type disc brake having a boot attached to the edge of an open end of a cylindrical portion of a caliper to slidably engage the outer circumferential face of a slide pin in an airtight manner. The boot is arranged to have the inner circumference of one end part thereof elastically expandable. The slide pin is provided with a tapered flange part at one end thereof in such a way as to expand and enlarge the end part of the boot. When the slide pin is inserted to a full extent into the cylindrical portion of the caliper, the tapered flange part causes the end of the boot to enlarge to allow an increased portion of air pressure which is increased within the cylindrical portion of the caliper by the insertion of the slide pin to escape to the inside of the boot through an air flow passage provided in the tapered flange part of the slide pin.