Patent GB-105324-A (GB)
IPC: B61L3/02
Abstract: 105,324. Turner, W. V. April 1, 1916, [Convention date]. Fluid-pressure.-In a track control mechanism for train brakes, the opening of a vent valve on the train by a track ramp actuates a train-pipe vent valve unless communication between the two valves is cut off by the energization of a third valve receiving current from the track ramp. Resetting is automatic. The train-pipe vent valve is returned by a .timing-reservoir after an interval, and the brakes thereby released. The cut-off valve, once closed, is retained in that position by a timing-reservoir to prevent premature reopening. The vent valve 8 is adapted to be opened by the upward movement of the track-operated shoe 5, whereby a cam 23 is caused to engage a lever 25. The cut-off valve comprises a differential piston 17, 18 adapted, in its upper position, to cut off the passage 16 from passage 28, and in the lower position shown, to connect these passages by an annular cavity 31. The piston 17, 18 is controlled by double-beat valve 20, 33 adapted to connect the passage 19, leading from beneath the piston 18, either to the pressure-fluid supply by passage 32, or, as shown, to atmosphere by port 44 in the stem of the valve. This valve is actuated by a magnet 6 connected to earth at 7 and to the track-operated shoe 5 The train-pipe control valve 11, 13. in its normal position shown, connects the main reservoir 14 to the train-pipe 15<1> by pipe 29. valve chamber 12, passages 41, 42, the usual gird-valve, and driver's valve 43. The timing-reservoir 39 is connected to exhaust port 40 in this position of the valve. When the cut-off valve is de-energized, the differential piston 17, 18 is maintained in the position shown by reason of the under face of piston 18 being open to atmosphere by port 44, and piston head 17 being subject to pressure by passage 28, cavity 31, passage 16, piston chamber 10, and port 30. Opening of the vent valve 8 by a de-energized track ramp vents the piston chamber 10 of the trainpipe valve 11, 13 by passage 16, annular valve cavity 31, and passage 28. The consequent movement to the left of the valve 11, 13 opens the train-pipe to exhaust port 40 by cavity 46 and pipe 15, and cuts off the pressure supply to the trainpipe by covering the passage 41, so that the brakes are applied. At the same time, the timing-reser. voir 39 is connected by cavity 37 and passages 47, 16 to the piston chamber 10, which thus continues to vent after closure of the valve 8 until the pressure in this reservoir equalizes through port 30 with that in the valve chamber 12, whereby the valve is returned by a spring 48 and the brakes are released. If the track ramp is energized, the magnet 6 seats the valve 33 and unseats the valve 20, so that the piston 18 is open beneath to the pressure air by passages 32, 19. The opening of valve 8 vents the space above piston head 17 at the same time. The piston therefore moves upwardly to cut off passage 16 from passage 28, and actuation of the train-pipe valve 11, 13 is prevented. A timing-reservoir 36 is open to the pressure-air supply by passage 32 in the open position of the cut-off valve. In the closed position of this valve, the reservoir is open to the under face of piston 18, and the valve is therefore maintained in this position after de-energization of the magnet 6 until the reservoir has exhausted by port 44.