Patent ID: 8419552

Claim:
A torque limiter comprising: a cylindrical member; and a shaft member which is fitted rotatably in the cylindrical member, the cylindrical member having a main body portion having in an interior thereof an oil pressure expansion chamber for pressing an inner circumferential surface of the cylindrical member against an outer circumferential surface of the shaft member and an oil release passage which is opened to the oil pressure expansion chamber at one end portion while being closed tightly at the other end portion and which is positioned further radially outwards than an outer circumferential surface of the main body portion, wherein the oil release passage includes a tube extending radially from the shaft member and an oil release bore communicating between the tube and the oil pressure expansion chamber, the shaft member having a circumferentially extended flange portion extending radially outward from the outer circumferential surface of the shaft member and having an axially extending portion which is extended circumferentially a predetermined dimension around the outer circumferential surface of the main body portion of the cylindrical member, the circumferentially extended flange portion having a circumferentially extended groove formed in an inner circumferential surface of the axially extending portion and which is extended in the circumferential direction, a threaded hole which is opened radially outwards and to the circumferentially extended groove and which is extended radially through the axially extending portion and a cap member which is screwed in the threaded hole, wherein: in such a state that the cap member is screwed in the threaded hole and the tube is received within the cap, when the cylindrical member stays still relative to the shaft member, the oil release passage is closed to the outside, whereas when the cylindrical member rotates relative to the shall member, the tube is broken by the cap member, whereby the oil release passage is opened to the outside; and in such a state that the cap member is not screwed in the threaded hole and in such a state that the oil release passage is not opened to the outside, when the cylindrical member is rotated relative to the shaft member, the tube moves in the circumferential direction within the circumferentially extended groove while being spaced apart from the circumferentially extended groove.