Patent GB-503481-A (GB)
Title: Improvements relating to slack adjusters for brakes
IPC: B61H15/00
Filed: 1937-10-04
Abstract: 503,481. Compensating for wear in brakes. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., KERSHAW, A. G., and LEECH, K. H. Oct. 4, 1937, No. 26814. [Class 103 (i)] In an automatic slack adjuster for brakes comprising a link in the transmission the affective length of which is adjusted by screwing one part of the link into another part, rotation of one part to effect the adjustment is effected by a quick-pitch screw-and-nut device which travels with the link during the application of the brake but of which the nut part is held by a stop if the travel is excessive and effects the rotation of the other part. In Figs. 1 and 2a the link or pull-rod comprises a rod 6 screwed into a tubular part 4 which transmits the pull to a rod 1 by the engagement of the reduced end 8 with the end 1<1> of the rod 1. A sleeve 17 splined to the rod 1 by projections 18 engaging slots in the rod has a quick-pitch thread at 16 engaging a corresponding thread on a sleeve 12 rotatable on the rod 1 and having ratchet teeth on its end face at 11 engaging teeth on the part 8 of the rod 4, reverse rotation of the rod 4 being prevented by the engagement with the part 8 of teeth on an inner sleeve 20 coupled by a pin-and-slot 22 to the rod 1. The sleeves 12, 20 are urged to engagement with the part 8 by springs 14, 23. In an application of the brake, the link with the sleeve 17 moves to the right and if the movement is excessive a lug 24 on the sleeve engages the stop 27<1> on a stationary rod 25 thus effecting rotation of the sleeve 12, the teeth on which slip over those on the part 8 while during the return movement the reverse rotation of the sleeve 12 turns the part 8 and the rod 4 relatively to the rod 6. To permit, re-setting of the device, the rod 6 is held against rotation with respect to the forked attachment member 28 by a Collar 29 splined on the rod and normally engaged by dogs at 31 with the member 28, but which can be slid back against the spring 32 to enable the rod to be turned by handles 33. In Fig. 3, the link comprises a non- rotatable sleeve 38, an intermediate rod 37 screwed into the sleeve and an end part 34 which transmits the pull to the rod 37 by a part 35 engaging a nut 36 on the rod 37. An outer sleeve 48 has secured thereto an inner sleeve 51 which has a quick-pitch thread at 47 engaging a similar thread on a sleeve 45 rotatable on the rod 37. Ratchet teeth on the end face 43 of the sleeve 45 engage similar teeth on a collar 42 fixed to the rod 37. Reverse rotation of the rod 37 is prevented by engagement of teeth on the collar 42 at 44 with teeth on a collar 56 rotation of which is prevented by splines 58 engaging slots 52 in the sleeve 51, rotation of which and the outer sleeve. 48 is prevented by splines 59 on the part 35 with the slots 52. Excessive movement of the link brings the lug 60 on the sleeve 48 against the stop 661 thus rotating the sleeve 45 while re-engagement with the lug 66 during the release movement turns the sleeve 45 reversely and thus also the rod 37 in the sleeve 38. A pre-loaded spring 64 disposed between the rod 61 and a sleeve 62 anchored at 63 permits movement of the rod to allow application of the brake should there initially be an extraordinary amount of slack. The other end of the rod of which the sleeve 38 is at one end is provided with a hand-wheel for re-setting and which is normally locked against rotation by engagement with a trunnion by which the link is attached to an operating lever of the mechanism; the hand wheel can be disengaged by a pull thereon.