Patent GB-1000059-A (GB)
Title: Improvements in automatic axially-acting two-way slack adjusters for railway vehiclebrake mechanisms
Inventor: SANDER NILS BORJE LENNART
IPC: B61H15/00
Filed: 1964-01-07
Abstract: 1,000,059. Railway brake slack adjuster. SVENSKA A.B. BROMSREGULATOR. Jan. 7, 1964, No. 636/64. Heading F2E. A slack adjuster for railway brakes automatically takes up slack on application of the brake, but will pay out to increase insufficient clearance only after two consecutive brakings with insufficient slack. This avoids premature paying out owing to stiffeness due to ice, dirt &c., which stiffness would be overcome during the first braking operation. The adjuster comprises a barrel 22 resiliently mounted at 30 in the end of cylinder 5, a brake piston 6 acting on a rod 7 connected to a live brake lever, a screwed rod 21 within the barrel and connected by its eye to a dead brake lever, an adjuster nut 38 providing clutch faces c, d engageable with corresponding faces on the barrel, a leader nut 37 having a clutch face a engageable with a corresponding face on a sensing sleeve 41 having a face e axially engageable with a corresponding face on a tubular sensing member 26 attached to the piston 6. Normal operation.-On brake application, piston 6 moves leftwards and surfaces e-e engage as the brake shoes reach the wheel rims. The thrust in rod 21 now increases substantially, spring 34 compressing to move rod 21 leftwards to disengage surfaces c-c and engage surfaces d-d to transmit the force through faces d-d, sleeve 46, barrel 22, support member 31, spring 32 to cylinder 5 secured to bolster 4. Further movement of piston 6 leftwards compresses spring 34 and disengages clutch a-a, nut 37 moving leftwards along the rod 21 under the action of spring 39. On brake release the piston moves to the right, clutch e-e disengages, parts 35, 34, 41, 44, 45, 39 and 40 rotate back with the leader nut as spring 34 expands until the braking force decreases to a valve where b-b re-engage, d-d disengages and c-c engages. Take up of wear.-If clearance exists surfaces e-e abut early and leftward movement of piston carries with it sleeve 41 to compress spring 64 and disengage faces a-a to allow leader nut 37 to rotate to increase the distance between support 44 and nut 38 to a dimension S (not shown) corresponding to the excess slack. When the force on rod 21 exceeds that of spring 34, clutch faces c-c, d-d disengage and engage respectively. The remainder of the application and the initial release occur as before. When, on release, faces b-b are engaged, but the cylinder pressure is still falling, clutches d-d and c-c are both disengaged and nut 38 rotates to move a distance S axially until the nut engages the support. The rod has thus extended the required distance S and the piston continues to withdraw until surfaces e-e are again separated by the required dimension A. Paying out.-If the clearance is too small, spring 32 is overcome during application while the surfaces e-e are a distance M (not shown) apart. Clutches c-c, b-b are disengaged, clutch d-d engaged and spring 34 rotates nut 37 with parts 35, 34, 41 rightwards, split ring 45 moving rightwards through distance M until e-e engage. During the remainder of braking and the early part of release nut 37 will idle as before. The distance between parts 44, 45 will remain M and e-e will be A-M apart when the brake is released. During a second brake application the blocks engage the wheel early and c-c disengages, adjuster nut 38 rotating with its spring 39. Spring 34 is compressed and rod 21 moves a distance M axially to the left to increase its slack by that amount.