Disc brake with parking brake mechanism

Abstract

A parking brake mechanism in a disc brake includes a bottomed tubular adjusting nut slidably fitted in a bore defined in a cylinder bottom coaxially with a piston with a seal ring interposed and having a closed end projecting into the cylinder and coupled to piston, an adjusting bolt axially movably threaded in the adjusting nut and having a head projecting out of the cylinder, a first spring interposed between the head and the cylinder bottom for normally urging the adjusting bolt in a direction out of the cylinder, a thrust bearing interposed between the head and the first spring for ensuring smooth rotation of the adjusting bolt, a pusher disposed coaxially with the adjusting bolt and having in one end a slot substantially perpendicular to an axis of the adjusting bolt, the pusher serving as a clutch for selective engagement with the head, a second spring for normally urging the pusher in a direction out of the cylinder, a plate having an intermediate portion extending through the slot and interposed between the pusher and the head, the plate serving as a second thrust bearing selectively engageable with a central top surface of the head, a cam shaft rotatably supported by a caliper and having a cam slot opening toward an opposite end of the pusher, the cam shaft having a parking lever secured thereto, and a toggle interposed between the cam slot and the opposite end of the pusher for axially moving the pusher in response to angular displacement of the cam slot.