Patent GB-1537507-A (GB)
Title: Mechanical disc brake
IPC: F16D65/14
Filed: 1976-02-13
Abstract: 1537507 Mechanically actuated disc brake; wear adjustment TOKICO Ltd 13 Feb 1976 [17 Feb 1975 18 Feb 1975] 05681/76 Heading F2E One pad 4 of a disc brake is fixed to a slidable calliper 1 while the other pad 8 is slidably mounted, the pad 8 being actuable by an adjusting bolt 16 abutting it; the adjusting bolt 16 threadingly extends through a nut member 12 mounted in a cavity 9 in the calliper 1 androtatable-by a brake actuating lever 15, the rotation of the nut member 12 being converted into axial movement thereof by means of a ball and ramp mechanism 10, 11, 13, 14 and this axial movement of the nut member 12 being transmitted to bolt 16 to thereby cause movement of pad 8; the bolt 16 is rotatable (manually or automatically) to adjust for wear of pads 4, 8 but a rotation control member 17 is mounted on the pad 8 and co-operates with an end portion 16b of the bolt 16 for controlling rotation of the bolt 16. In the embodiment of Figs. 1-3 the calliper 1 is slidingly supported on a fixed supporting member 2 by means of bolts 3, and a hole 7 is formed in member 2 to slidably receive the pad 8. The rotation control member 17, which is secured to backing plate 8a of pad 8 by pins, is in the form of a pinched and pressed steel plate formed with a hole through which passes the portion 16b of the bolt 16 which portion 16b if of hexagonal shape, the inner edges of the hole defining engaging portions (17a) for engagement with two opposite surfaces of the hexagonal portion 16b. The ball and ramp mechanism comprises a rotationally fixed ramp member 10 formed with three inclined grooves 11 receiving respective balls 14 also received in complementing inclined grooves 13 in the nut member 12. A wavy washer 18 urges the nut member 12 towards ramp member 10. To actuate the brake, a cable attached to brake lever 15 is pulled by a pedal or lever to rotate nut member 12 with consequent axial movement thereof to axially move bolt 16 and pad 8. The bolt 16 does not rotate at this stage. The calliper 1 thereafter moves slidingly on support 2 to apply pad 4 to disc D, and the thrust exerted on bolt 16 causes the bolt 16 and nut member 12 to rotate together, the member 17 allowing rotation of the bolt 16 for a predetermined range. When the cable is released the brake lever 15 and nut member 12 are urged to rotate in a reverse direction by a return spring and they and the bolt 16 return to their original positions. To adjust for wear of pads 4, 8 a rubber plug 23 is removed to allow access to the bolt 16 which may then be turned with a tool. In modifications of this embodiment the portion 16b is octagonal and the pad 8 is supported on the calliper 1 rather than supporting member 2. In the embodiment of Figs. 4-6 the rotation control member 17<1> is formed with pawls 171a for engagement with the portion 16<1>b which is formed as a ratchet to give automatic wear adjustment. Figure 7 (not illustrated) shows a modified rotation control member (17<11>) having the form of flat plate with two pawl portions (17<11>a). In the embodiments of Figs. 4-6, 7 it is possible to form the ratchet teeth on a member attached to the pad 8 and the pawl on the bolt 16. Also the pad 8 may be slidably supported on the calliper 1.