Patent GB-1093616-A (GB)
Title: Disc brakes
Inventor: BUTLER HENRY JAMES
IPC: B60T13/02
Filed: 1964-03-17
Abstract: 1,093,616. Disc brakes. DUNLOP RUBBER CO. Ltd. March 4, 1965 [March 17. 1964]. No. 10325/65. Heading F2E. A disc brake comprises a rotatable disc having a caliper housing 2 surrounding a portion of a periphery of the disc and a pair of friction elements 15, 20 associated with the caliper housing one on each side of the disc and means for effecting frictional engagement of the friction elements with the disc, a lever mechanism 14 being mounted in one limb 4 of the caliper housing and arranged to operate in a plane connecting the axis of the disc and passing through the limb. The lever mechanism comprises a first lever 26 engageable at one end by a brake operating device in the form of a hand brake operated cable 24 or an hydraulic piston and cylinder mechanism 25 and movable thereby about a fulcrum formed by a pair of pins 27 at the other end of the first lever. A second lever 28 is pivotally connected at one end by a pin 29 to the first lever and mounted between its ends on a pivot 30 secured to the caliper housing, the other end of the second lever being arranged to apply pressure to a friction element 15 through a trunnion block 31 which bears against a thrust member 32 arranged to apply axial pressure to the movable friction element 15. The thrust member 32 is provided with an automatic screw threaded adjustment device having a pawl and ratchet mechanism to take up play arising from friction pad wear. The lever mechanism 14 is enclosed within a sheet metal casing 43 adapted to fit against the outer face of the limb 4 of the caliper housing to protect the lever mechanism from the ingress of dirt. The caliper housing 2 is mounted on a pin 6 supported in a non-rotatable support 3 and the housing is prevented from rotating about the axis of the disc by the engagement of a pair of lugs 10 formed on the housing with abutments 11 on the support 3. The pin 6 is provided at one end with a retraction device 12 which moves the housing after each braking operation to a position in which the shorter limb 5 of the caliper housing which carries the friction element 20 fixed thereto, is at a predetermined distance from the adjacent braking surface of the disc. The caliper housing is thus movable in a direction parallel to the axis of the disc. Alternative embodiments are disclosed in the Specification (Figs. 8, 9, 11 and 12, not shown) wherein the caliper housing is arranged to be movable about the axis of the pin 6 under the drag force exerted by the rotating disc during braking, a linkage being provided to oppose such movement of the housing and thereby generate a force which can be transmitted to the brake applying mechanism of the same brake or of another brake to cause a self-servo action to enhance the thrust applied to the friction elements. The linkage may comprise a pair of links connected to the housing one on each side of the pin 6 and connected respectively to a pair of levers fixed to a shaft rotatably mounted on a fixed support at right angles to the pin 6, the links being arranged so that one of the links turns the shaft when the housing is rotated in either direction about the axis of the pin and a cable tension transmitting device is provided to enable the rotation of the shaft to apply a force to the brake applying mechanism of the same brake or of another brake or a pair of brakes.