GB1442834A - Spring-applied brake actuator - Google Patents

Abstract

1442834 Spring-applied actuators; transmitting mechanisms WESTINGHOUSE BREMSEN UND APPARATEBAU GmbH 18 Oct 1973 [19 Oct 1972] 48709/73 Headings F2E and F2F A piston 4 of a vehicle brake actuator is movable under the action of a spring 7 to pull the core 14 of a Bowden cable and cause application of a brake; release of the brake may be effected by the manual release of a locking device arranged between the piston 7 and the core 14. In the embodiment of Fig. 1, a threaded pin 17 at the end of the cable core 14 is retained by a nut 18 in a threaded hole 19 of a locking sleeve 21 which is arranged to be locked in a tube 22 firmly connected with the piton 4. To this end an internal groove 23 running round tube 22 holds locking balls 24 in radial holes 25 in the sleeve 21 on a tubular shoulder 26 of a shoulder locking pin 27, the shaft 30 of which leads outside the actuator. The guide tube 22 is movable in a guide 29 fitted in an end wall 31 of the actuator housing 3. In the event of a desired or undesired fall of pressure in a pressure chamber 2, the spring 7 moves the piston 4 to the right, taking the tube 22 and the locked locking sleeve 21 with it and pulling the core 14 which is fixed to a brake lever. To release the brake manually without the application of fluid pressure to chamber 2 the operator strikes the shaft 30 and when the tubular shoulder 26 passes the drillings 25 the locking balls 25 are released and the locking sleeve 21 is pulled toward the left by the tension in cable core 14, and the brake is thus released. When pressure acts once again on the piston 4 the device is automatically locked. In the embodiment of Figs. 2, 3 the tube 122 connected to piston 104 carries a profile ring 133 equipped with internal grooves 134, 135 adjacent one of which is a stop 136. A reduced diameter part 138 of a locking bar 142 provided with guide cams 139, 141 extends into the ring 133 and the threaded pin 117 of the Bowden cable core 114 is attached inside the reduced part 138. To release the brake manually a rotary movement is applied to the bar 142 until the guide cams 139, 141 are over the grooves 134, 135, whereupon the cable core 114 pulls the bar 142 through the ring 133. To relock the device the piston 104 is acted upon by pressure and the tube 122 and ring 133 are thereby moved leftwards. When the cams 139, 141 are free from grooves 134, 135 a torsion spring moves the bar 142 to a locked position.