GB110740A - Improvements in and relating to Fluid Pressure Braking Apparatus. - Google Patents

Abstract

110,740. Turner, W. V. Oct. 21, 1916, [Convention date]. Fluid-pressure.-In an electro-pneumatic brake system for double-ended cars, the circuit of a release magnet is completed in the " handle-off " position of the driver's valve and switch, so as to keep the brakes on while the driver is changing ends and release is automatically effected when the valve is turned to running position at the opposite end of the car. The release may be effected by a pneumatically actuated switch interposed in the release magnet circuit. The equipment shown comprises the valve mechanism 1 having release, service, and emergency magnets 2, 3, 4, and an automatic train pipe 6 controlled by a combined switch and valve device 7 arranged at each end of the car. The release magnet 2 closes and opens the brake cylinder exhaust according as it is energized or de-energized. The penumatically controlled switch 11 is interposed at each end of the car in the release magnet circuit and comprises a piston 15 carrying contacts 16 for engagement with fixed contacts 17. A piston slide valve 20 controlling the admission of pressure air beneath the switch piston 15 is itself controlled by differences of pressure in the equalizing reservoir 26, and the train pipe 6, the reservoir being connected to chamber 19 by passages 24, 25, and the train pipe to chamber 21 by passage 23. In the normal position shown, these pressures are equal and the switch piston cylinder 13 is open to exhaust port 30 by passage 28 and valve cavity 29 so that the switch 16, 17 is closed by spring 31. Before leaving one end of the car, the driver applies the brakes and turns the handle to " off " position so that the release train wire 8 at that end is connected to the battery and the release magnet 2 is energized. In applying the brakes, the equalizing reservoir reduces equally with the train-pipe pressure and the switch 16, 17 remains closed. When the handle is turned to running position at the opposite end of the car, the trainpipe is recharged but the equalizing reservoir pressure at the non-operating end remains reduced since this reservoir is cut off from the train-pipe in the " handle off " position of the valve 7. The slide valve 20, 21 therefore moves to the right uncovering the passage 34 so as to admit air from the train-pipe beneath the switch piston 15, thereby disengaging the contacts 16, 17 and releasing the brakes. The equalizing reservoir is at the same time connected by cavity 29 and port 24<1> to exhaust port 30 to prevent possible building up of pressure in this reservoir.