GB1280725A - Brake actuating devices - Google Patents

Abstract

1280725 Compressed air braking systems KNORR-BREMSE GmbH 1 Oct 1969 [2 Oct 1968] 48306/69 Headings F2E and F2F In a train braking system compressed air is supplied to a brake cylinder 2 from a reservoir 46 by way of a control valve 48 and a locking mechanism is provided to hold the piston 4 in the brake-applied position when the air pressure in a train pipe 50 falls below a minimum level. The brake actuating piston 4 carries a barrel 5 through which passes a piston rod 6, the barrel having a threaded portion 7 engaging a non- locking nut 8 provided with teeth 11 engageable by a pawl 12 of a lever 13. Lever 13 is pivoted at 14 to an arm 19 having a section 22 which engages a stop 28 on an arm 26 of a latching lever 23. Lever 13 passes through an orifice 35 of a piston rod 34 having a piston 31 biased downwardly in a chamber 29 by a spring 33, so that on loss of pressure to chamber 29 applied through port 44 piston 31 moves downwardly to pivot lever 13 and cause pawl 12 to engage teeth 9, rotation of nut 8 and movement of piston 4 and barrel 5 into the brake release position thus being prevented. To release the brakes manually lever 19 is swung against the force of a tension spring 21 to engage an abutment 18 carried by lever 13, the section 22 of the lever 19 engaging a stop 28 to free the latching lever 23 which swings under the action of a spring 27 with stop 28 behind lever arm 22 of the hand lever 19 which is thus held released. The locking mechanism may also be released by a vacuum through a port 52 of a second chamber 30 to move a piston 32 against a spring 38, a pin 39 carried by the piston which normally engages the first piston 37 through a port 40 disengaging the piston 37 which moves upwardly under the action of spring 36 and engages a collar 56 of the piston rod 34 causing piston 31 to pivot lever arm 13 and disengage pawl 12 and teeth 11.