Patent GB-182890-A (GB)
Title: Improvements in and relating to brake systems and apparatus for railway and like vehicles
IPC: B61H9/00
Filed: 1921-04-07
Abstract: 182,890. Cross, J. W., and British Air Brake Co., Ltd. April 7, 1921. Fluid-pressure.-A brake system in which a compressed-air brake on a locomotive is arranged to be controlled by the pressure in the train-pipe of the vacuum brakes with which the train is provided has the following features :-the pressure established in the locomotive brake cylinder is dependent upon the increase effected in the trainpipe pressure; a valve is provided adapted to delay the application of the locomotive brake until the train-pipe pressure has been increased a predetermined amount; this delay valve is rendered operative when the electric regenerative brake on the locomotive is operative; the delay valve may also be arranged to break the circuit of the electric power supply and of the regenerative brake of the locomotive when the predetermined increase in train-pipe pressure has been effected. The distributing valve on the locomotive may be manually operable. The distributing valve R for the locomotive comprises a diaphragm 4 subject on the one side to the pressure of a spring 27 and to that in the vacuum train-pipe 1 connected at 10 and on the other side to atmospheric pressure in the chamber 5. The diaphragm is attached to a rod 13 to which is also connected a piston 15 subject in the chamber 6 to the pressure in the locomotive brake cylinder connected at 7. The rod 13 actuates the brake cylinder exhaust valve 21 by a cam surface 24 and also the pressure supply valve 17. The delay valve D is similar to the valve R except that the spring 27<d> thereof is weaker than the spring 27 and that there is no piston 15. There is associated with the valve D a cylinder 35 the piston 38 of which actuates a switch 39 in the locomotive power circuit and it may be also in the regenerative brake circuit. The compressed air supply for the locomotive brake is connected to the valve D by the pipes 2, 34. The valve D can be by-passed by a valve B comprising a loosely fitting piston 46 past which the pressure air from the pipe 43 can equalise into a lower chamber 47 when a valve 53 is closed so that the spring 48 then holds open the valve 45. The valve 53 is controlled by a magnet 52 in the regenerative brake circuit and is closed when this brake is not operative. If in these circumstances air is admitted to the vacuum train-pipe 1, the diaphragm 4 will be moved to the right to close the exhaust valve 21 and open the valve 17 so that air will be admitted to the locomotive brake cylinder by pipes 2, 43, 44, 9, 7 until the pressure in the cylinder acting on the piston 15 is sufficient partly to return this piston and the diaphragm 4 and permit the valve 17 to close. If however the regenerative brake is in operation the valve 53 and chamber 47 of the valve B will be open and the pressure in the pipe 43 acting on the greater area of the piston 46 as compared with that of the valve 45 will close this valve. In these circumstances air can be supplied to the locomotive brake cylinder only by way of the 'delay valve D which is not actuated by an increase of the train-pipe pressure corresponding to a moderate application of the vacuum brakes on the train. If however the train-pipe pressure is increased beyond this value the valve 17d is opened by the spindle 13d and air is supplied by way of the pipes 34; 33, 9 the valve 17 and pipe 7 to the brake cylinder. By the opening of the valve 17d, air is also supplied beneath the piston 38 thereby breaking the propulsion circuit by opening the contacts 39. If the piston 38 is also arranged to break the regenerative brake circuit the valve B will be opened by the de-energization of the valve 53 and air will thus be supplied to the brake cylinder past this valve as well as to the valve 17d. When the train-pipe pressure is restored the valves B and D return to the position shown and the brake cylinder and switch cylinder 35 exhaust by the valves 21 and 21d respectively. A manually operated valve may be disposed in a pipe connecting the pipes 33, 34, to cut out the delay valve D. The rods 13, 13d of the valves R, D may each be fitted with a knob or lever to permit operation of these valves by hand.