GB186645A - Improvements in and relating to brake mechanism - Google Patents

Abstract

186,645. Wilson, W. G. April 29, 1921. Compensating for wear; band or coil; blocks acting on drums.-In a device for taking up wear automatically, the adjusting element and the device which actuates and locks it move together when the brakes are applied through a definite distance after which relative movement takes place to unlock the adjusting elememt, and if the relative movement exceeds a predetermined amount owing to wear of the brakes, the actuating- device moves the adjusting- element to take up the slack on the brakes being released. Fig. 1 shows the application to a brake comprising blocks 17 mounted on levers 19, 20 pivoted at 21, and actuated by a pull-rod 29 through a toggle system 21, 22. The slack-adjusting element consists of a ratchet-wheel 26 formed in one with a nut 25 which works on the threaded end of the rod 22, and a loose fitting abutment member 27 between the nut 25 and the toggle member 24. The ratchet is actuated when necessary, and locked when the brakes are off by a member 32, Fig. 2, having an actuating tooth 34 and a locking tooth 33. The hooked end 35, 37 takes over a fixed pin 36, and a light spring 38 is provided. When the brakes are applied the ratchet-wheel 26 moves downwards, and the member 32 accompanies it until stopped bv the lug 35. Further move.- ment of the ratchet-wheel disengages it from the tooth 33 as shown in Fig. 2, and if the movement is excessive owing to wear of the blocks. the tooth 34 will engage behind a different tooth of the ratchet-wheel 26, and cause it to rotate when the parts return to their normal position on release of the brakes. Fig. 3 shows the application to a band brake inwhich the hand 42 is anchored at one end 44 to a fixed member 45 and is secured at the other to a rod 48 forming part of a toggle system 48, 53, 45. The brake is applied by a push-rod 61 engaging a square washer 49 on the rod 48. The slack-adjusting ratchetwheel 51 is formed with a nut threaded on the end of the rod 48. The ratchet is actuated when necessary, and locked when the brakes are off by a plate 56 which is pivoted at 57 upon the toggle member 53. This plate 56 has spring tongues 62, 63, a tooth 60, Fig. 4, engaging the ratchet 51. and a projection adapted to contact with one of the sides of the washer 49 when the brakes are taken off. The movement o the plate is limited by a fixed bar 59 passing through a recess 58. When the brakes are applied rod 48, ratchet 51, and plate 56 are pushed to the right. The plate is stopped by bar 59 and relative movement then takes place. If this movement is excessive owing to wear, the ratchet snaps over tooth 60 and will be rotated to take up the slack when the parts return to their normal position on release of the brakes.