Patent ID: 7779971

Claim:
A vehicular disc brake comprising a caliper body supporting a brake piston so as to be slidable in an axial direction of the brake piston, the caliper body comprising: an electric motor having a motor shaft; a speed reducer that reduces output from the electric motor and has a case; a motion converting mechanism that converts a rotation output from the speed reducer into axial operation force of the brake piston, is interposed between the brake piston and the speed reducer and has an input member disposed so as to be coaxial with the motor shaft, wherein the speed reducer comprises: an eccentric rotating member which has an outer circumference being eccentric with an axis line of the motor shaft and rotates together with the motor shaft; an outer gear which is coaxial with the eccentric rotating member and is rotatably supported by the outer circumference of the eccentric rotating member, and provided with outer teeth on an outer circumference thereof; an inner gear that is provided with inner teeth, of which number is larger than that of the outer teeth, on an inner circumference thereof so as to engage with the outer teeth and is fixedly disposed to the case of the speed reducer so as to be coaxial with the motor shaft so as not to rotate relative to the speed reducer; an output member which is connected to the input member of the motion converting mechanism so as to be not relatively rotatable about the input member; and an Oldham mechanism which is disposed between the outer gear and the output member so as to transmit only a rotational component of the outer gear.