Patent GB-161946-A (GB)
Title: Automatic compressed air brake for tramways and secondary railways
IPC: B60T15/04
Filed: 1921-04-12
Abstract: 161,946. Seguin, E. April 15. 1920, [Convention date]. Void [Published under Sect. 91 of the Act]. Fluid-pressure.-Compressed air brakes particularly for tramway vehicles and short trains are provided with operating valves, distributor valves and feed valves having double-seated lift valves. Fig. 3 shows one form of operating valve. Air from the main reservoir connected at A is supplied past the valve h<2> to the chamber H<1> up to the pressure determined by the spring h<4>, To charge the train-pipe the rod e<2> is raised by the handle e<1> to unseat the valve h<1> so that pressure air flows through the, chamber H to the trainpipe connected at D. At the same time air admitted by the passage k<1> to the space above the piston j opens the valve j<1> the space below this piston being opened to exhaust port k<5> by the piston h<3>. Air from the reservoir is thus also supplied to the train-pipe by the valve j<1> through the passages k, k<1>. If the handle e<1> is lowered to seat the valve h<1> the valve j<1> remains open and the slow supply continues. By raising the handle e<1> sufficiently, the valve h<2> can be unseated by the stem of the valve h<1> to supply the train-pipe directly. This communication ceases when the handle is released. To reduce the train-pipe pressure the handle is lowered to unseat the valve h thereby connecting the chamber H to the exhaust passage g; at the same time the piston h<3> uncovers the passage k<2> to the chamber H so that the valve j<1> is closed by the equalization of the pressures on the piston j. The valve j<1> can be re-opened to effect the slow charging of the train-pipe by raising the rod e<2> until it contacts with the valve h<1>, the piston h<3> then uncovering the passage k<2> to the exhaust port k<3>. The supply can be stopped by lowering the rod until the passage k<2> is connected to the chamber H, the valve h being slightly unseated. Figs. 7, 8 show modifications of the valve j which are closed by a sudden reduction in train-pipe pressure. In a simpler form of valve these are only the two valves corresponding to the valves h, h<1>, the main reservoir connection being direct to the chamber H<1>. The valve may be used either for straight air or automatic brakes. The feed valve shown in Fig. 6 comprises the valve N connected to a diaphragm N<1> under the pressure of air through passage n<1> and of a spring N<2> adjustable by the nut N<3>. The valve is connected to the main reservoir at A and to the operating valve at n<2>. The air supplied through the passage n<2> can be brought above the lift valve h<2>, Fig. 3, or this valve may be suppressed. Fig. 4 shows one form of distributor valve in the release position. Air from the train-pipe connected at D feeds into the auxiliary reservoir at F by the passages m. The piston J presses the valve J<1> on to its seat and raises the valve J<2> so as to connect the brake cylinder at G with the atmosphere by the passages m<1>, m<2>. When the train-pipe pressure is reduced, the piston J first moves the rod k<1> to permit closure of the exhaust valve J<2> by the spring l<1> and then unseats the supply valve J<1> so that air flows into the brake cylinder by the passage m<1>. For a graduated application the reduction in train-pipe pressure is stopped and when the auxiliary reservoir pressure has equalized therewith the spring l<1> which has been compressed returns the piston J sufficiently to permit the supply valve J<1> to close. The distributor shown in Fig. 5 is provided with a double piston J, J<4>, the part J moving within the part J<4>. When the train-pipe pressure is reduced, the piston J descends alone at first to permit the exhaust valve J<2> to close and then by contacting with the washer J<5> carries the larger piston J<4> until the heads of the pistons are seated upon the washer J<3> and the spring l<1> is compressed. The piston J<4> opens the supply valve j<1>. When the pressure in the auxiliary reservoir is equal to that in the train-pipe the spring l<1> raises the piston J; as soon as it has begun to move a larger surface is offered to the thrust of air and the piston J<4> rises to close the valve j<1>. The upward movement of the piston J is arrested by the engagement of the rod k<1> with the stem of the valve J<2>.