GB306269A - Improvements in or relating to vehicle brakes - Google Patents

Abstract

306,269. White, A. E., (Midland Steel Products Co.). Feb. 6, 1928. Band; blocks and shoes acting on drums; compensating for wear.-In a brake wherein the friction member which engages the interior of the drum comprises a relatively rigid portion and a flexible band portion as described in Specification 263,950, the rigid portion is formed of channel section. Devices for adjusting the friction member to compensate for wear and for preventing rattling thereof are described. The friction member comprises a shoe 12 of channel section to which is secured a flexible band 9. The end of the shoe 12 and also that of a member 30 adjustably secured to the band 9 are shaped to normally engage a fixed stop pin P under the influence of a spring 61 extending between the shoe 12 and member 30 and of a second spring 62 connected to the part 12 and a fixed point 63. The expanding means comprise upper and lower pairs of toggle links T<1>, T<2> connected to vertical pins passing through horizontal pins 20, 23 pivotally mounted in the ends of the shoe 12 and the member 30 thus providing a universal connection between the links and the friction member. The joint pin 25 of the toggle is connected by a yoke to a cable which may pass through a flexible conduit as described in Specification 263,950. To permit of adjustment of the effective length of the friction member to compensate for wear, the member 30 has a part 35, Fig. 4, slidably disposed between a pair of angle members 40, 41, secured to the band 9. A guide bolt 38 passes through the members 40, 41 and a slot in the part 35 and adjustment is effected by a wedge piece 50 carried by a screw 51 and engaging corresponding surfaces formed on the members 40, 41 and the part 35. An adjustable stop for the shoe 12 comprises a member 70 having a surface eccentric to the bolt 71 by which it can be turned. The inner flange of the shoe 12 is urged by the spring 62 against an indented part of the anchor plate to prevent rattle and its axial movement is limited by the engagement of the stop 70 with the other side of the flange. Rattling of the band 9 is prevented by the engagement of a spring urged plate 81 with a bent part 80 of the band, the band being thus forced against an indented part 88 of the anchor plate. When the friction member is expanded by the toggle, the end of the band 9 is first engaged with the drum by reason of the resistance of the spring 62 and assuming the rotation of the drum to be clockwise the end of the shoe 12 remains in contact with the anchor pin P. If the rotation of the drum is in the reverse direction the end of the band is carried back to the pin P and the end of the shoe 12 leaves the pin.