Patent GB-191010826-A (GB)
Title: Improvements in Air Brakes.
IPC: B60T15/18
Filed: 1910-05-02
Granted: 1910-11-17
Abstract: 10,826. Marks, E. C. R., [California Valve and Air Brake Co.]. May 2. Fluid-pressure.-In an automatic air-brake system, the triple valve is constructed so that the reductions of train-pipe pressure produce applications of the brakes by means of air from the train-pipe only until the brake - cylinder pressure becomes equal to that in the train-pipe, after which the further reductions of train - pipe pressure cause the triple valve to move so as to connect the brake cylinder to the auxiliary reservoir, the arrangement being such that the amount of air admitted to the brake cylinder is proportional to that exhausted from the train-pipe. Further, the construction is such that the brake-cylinder pressure when in excess of that in the train-pipe is released into the train-pipe, but is released directly to atmosphere when less than that in the trainpipe. A special form of driver's valve, Fig. 3, is also described, and comprises a main valve 43 operated by a piston 34, which is controlled by air admitted by a pilot valve 20 operated by a handle 31. This handle engages a non-rotatable screwthreaded stem 27 connected by a spring to a diaphragm 22, which carries a second stem 25 engaging an arm 21 connected to the valve 20. The valve 43 is provided with a similar arm which engages the piston-rod 38. Each of the valves 20, 43 is formed with a supply port 46 and with a release groove 47 co-operating with a casing-port 48, and the interior of each valve communicates with the main reservoir. The chamber 36 at the left of the piston 34 communicates with the trainpipe, while the chamber 35 at the other side communicates with the underside of the diaphragm 22. When the handle 31 is rotated, the pilot valve 20 is moved to admit air until sufficient pressure has accumulated to raise the diaphragm 22 and close the valve. The air thus admitted moves the valve 43 so as to open the port 46 to the train-pipe until the pressure in the chamber 36 is sufficient to return the piston and the valve 43. The consequent increase in pressure in the chamber 35 raises the diaphragm 22 so as to open the release groove 47 of the pilot valve, thereby reducing the air pressure to that for which the handle 31 was set. The triple valve, Fig. 7, comprises a rotary valve 91 which is in operative connexion by means of an arm 92 with a piston 57, the rod 62 of which slides within the rod of a second piston 58, which is connected by a lever 72 to a diaphragm 66. The right-hand sides of the piston 57 and diaphragm 66 communicate reapectively with the train-pipe and auxiliary reservoir. The triple valve is further provided with a secondary valve 137, Fig. 11, which engages a seat 136 and is controlled by a piston 131 arranged above the valve 91. The upper side of the seat 136 communicates with the auxiliary reservoir, and the lower side with the brake cylinder. The chamber 61 to the left of piston 58 communicates by a port 123 with the valve 91, and, except when this valve is in the full or direct release position P<1>, Fig. 7, communicates with the atmosphere by a groove 119, Fig. 11, and port 121. Figs. 9 and 10 show the valve 91, when in the position P', in sections taken on lines y and x respectively of Fig. 25. In this position, the brake cylinder is open to atmosphere by ports 100, 99, 98, 105, Fig. 10, while the auxiliary reservoir is charged by ports 112, 116, Fig. 9, and a port 117, Fig. 22, which is provided with a check valve 117<a> and communicates by a groove 117<b> with the upper side of the valve seat 136, Fig. 11, air passing to the interior of the valve 91 from the train-pipe by ports 106, 97, Fig. 10. When the auxiliary reservoir is fully charged, all the chambers of the triple valve will be at full presure, say 100 lb., train-pipe air passing to the chamber 61 by ports 124, 123, Fig. 9, and to the middle chamber 60 by ports 96, 95, Fig. 10. When the train - pipe pressure is reduced, say by 10 lb., the corresponding reduction in the chamber 59 of the triple valve (auses the pistons to move to the right, thereby bringing the valve 91 to lap position P', Figs. 7 and 8, which also show sections on lines x and y respectively of Fig. 25. The central chamber 60 then vents into the brake cylinder by ports 109, 108, 111, Fig. 8, and 99, 100, Fig. 7, whereupon the pressure in the diaphragm chamber 68 moves the valve to position P<3>, Fig. 15, thereby allowing train-pipe air to pass to the brake cylinder by ports 106, 97, 96, 99, 100. Since the chamber 60 is still in communication with the brake cylinder by the grooves 108, 111, Fig. 8, the pressure in this chamber is correspondingly increased until sufficient to return the valve to lap position P<2>, the arrangement being such that the pressure obtained in the brake cylinder is equal to the reduction made in the train-pipe. The venting of the train-pipe into the brake cylinders throughout the train gives an accelerated and more uniform application of the brakes. Successive applications of this nature may be made by further venting of the train-pipe until the pressure therein becomes equal to that in the brake cylinder, namely 50 lb. The pressure in the chamber 60 is then insufficient to return the valve to lap position P<2>. If the train-pipe pressure is then further reduced, the piston 57 is moved to the position P<5>, Figs. 11 and 14, extending the pistonrod 62 as shown, whereupon air passes from the brake cylinder by ports 100, 99, 96, Fig. 14, and 112, 114, Fig. 11, to the underside of the piston 131, thereby raising the valve 137 and allowing air to pass from the auxiliary reservoir to the underside of the seat 136 and thence to the brake cylinder. When the auxiliary-reservoir pressure becomes sufficiently reduced, the triple valve is raturned to lap position P<4>, Fig. 7, by the corresponding reduction of pressure in the chamber 68. For releasing the brakes, after applications from the auxiliary reservoir, an increase of train-pipe pressure returns the triple-valve to the position P<3>, in which the train-pipe communicates directly with the brake cylinder as described above, so that the brake cylinder being now at the higher pressure, releases into the train - pipe. The chamber 60, being in communication with the brake cylinder, is correspondingly vented and returns the triple valve to lap position P<4>. When the brake - cylinder pressure becomes less than that in the trainpipe, the piston - rod 62 is moved back to the position shown in Fig. 7 so that the triple valve takes up the full-release position P<1>. Indicators, applications of.-The handle 31 of the driver's valve, Fig. 3, is formed with an index 56, which moves over an indicator dial 55, Fig. 6, the outer and inner numbers on which indicate approximately the brake-cylinder and train-pipe pressures respectively, the upper half of the dial corresponding to applications by means of train-pipe air, and the lower half to applications by air from the auxiliary reservoir.