Patent GB-421759-A (GB)
Title: Improvements in or relating to automatic slack adjusters for brakes
IPC: B61H15/00
Filed: 1933-12-04
Abstract: 421,759. Transmitting-mechanism for brakes. SVENSKA AKTIEBOLAGET BROMSREGULATOR, Malm÷, Sweden. Dec. 4, 1933, No. 34013. Convention date, Dec. 22, 1932. [Class 103 (i)] Relates to automatic slack-adjusters for brake mechanism which are adapted both to reduce excessive slack and to increase insufficient slack such increase being effected by the stress arising in the mechanism when the brakes are applied and being limited by a locking device operated on the completion of a predetermined stroke. In order to prevent failure of the operation of the locking device in dependance upon the stroke from causing an excessive reduction of slack the locking device is adapted to be operated by the stress in the adjuster when the brakes are applied in the event of such failure. Fig. 1 shows the adjusting device shown in Fig. 2 of Specification 353,897 with the addition of a cylinder 11<a> connected to the chamber 4<1> on one side of the piston 6 and containing a piston connected to the cock 11 whereby the cock is closed as soon as the pressure in the chamber 41 increases upon an application of the brakes, in the event of failure of the connections 11<1> by which the cock is normally closed when the brake-operating piston has completed a predetermined stroke. The adjuster shown in Fig. 3 of Specification 353,897 is also shown and in this case the housing 19 has frictional engagement with the ring 28 which actuates the locking device so that in the event of failure of the operation of the ring in dependance upon the piston stroke, it will be operated by the rotation of the housing under the stress in the adjuster. Fig. 3, shows the application of the invention to a further known construction of the kind in which the adjuster comprises members 41, 48 having quick-pitch screw-threaded engagement so that lengthening of the adjuster is effected by the tension therein when the brakes are applied. A rotatable housing 45 has screw-threaded engagement 47 with the non-rotary part 43, 44. In applying the brake the stress is at first transmitted from the member 48 to the member 43 through the members 41, spring 50, members 51, 45 and screw-thread 47. Rotation of the housing 45, at the completion of a predetermined stroke by linkage connected at 30 moves the housing to the left and engages the ring 40 on the member 41 with the non-rotary member 44 to lock the member 41 against rotation and thus limits the lengthening of the adjuster. Shortening of the adjuster to take up excessive slack is effected by the return rotation of the housing 45 which turns the member 41 through a one-way clutch spring 52, clutch rings 51 and 42. According to the invention in this case the screw-thread 47 is made non-self-locking or nearly so, so that in the event of failure of the connections at 30 by which the housing 45 is normally rotated to lock the member 41, the housing will be rotated by the tension which arises in the adjuster when the brakes are applied assisted by the rotation of the member 41 transmitted frictionally through the rings 42, 51. and clutch spring 52 and also by the direct engagement of the ring 51 with the housing as shown.