GB424228A - Improvements in and relating to automatic vacuum braking apparatus - Google Patents

Abstract

424,228. Vacuum brakes. BROWN, D. F., and WESTINGHOUSE BRAKE & SAXBY SIGNAL CO., Ltd., 82, York Road, King's Cross, London. Dec. 29, 1933, No. 36593. [Class 103 (i)] In automatic vacuum brake systems of the kind in which a supplementary reservoir is connected to the lower chamber of the brake cylinder to accelerate the release of the brakes, a cut-off valve is provided for preventing the reservoir from being exhausted when the vacuum in the train-pipe or lower cylinder chamber is below a relatively high value corresponding almost to complete release of the brakes. The cut-off valve device for the reservoir 1 comprises a non-return valve 13, the stem of which engages a diaphragm 17 subject on its upper side to a spring 20 and to the vacuum in the train-pipe 2 through passages 3<1>, 3 and non-return valve 4 and on its lower side to atmospheric pressure. The diaphragm 17 may instead be subject on its two sides to the vacuum in the upper and lower cylinder chambers. Thus unless the train-pipe vacuum is substantially at the normal release value the valve 13 is seated and prevents flow of air from the reservoir to the train-pipe which when the reservoir has equalized with the lower cylinder chamber would delay the further release of the brakes. The valve 13, however, permits flow of air at any time from the lower cylinder chamber to the reservoir under the control of a quick release valve device 6 such as described in Specification 424,500 and which comprises a diaphragm 8 subject in chambers 9, 10 respectively to the vacuum in the train-pipe 2 and lower cylinder chamber connected to pipe 5. The apparatus shown also includes a quickapplication device 21 comprising a diaphragm 24 subject to the vacuum conditions in chamber 25 connected to the train-pipe and in chamber 26 connected through passage 27 with a quickinshot valve device 22. The diaphragm 24 actuates a valve 23 which is normally seated to cut off the atmosphere from chamber 26. The device 22 comprises a diaphragm 31 subject on its two sides respectively to the vacuum conditions in the upper and lower cylinder chambers through passages 33, 5 and spring 35 and normally lifts a valve 30 to establish communication between chamber 26 and the lower cylinder chamber.