Patent GB-1199995-A (GB)
Title: Railway Braking Apparatus
Inventor: MOORE IVAN GEOFFREY
IPC: B60T17/20
Filed: 1967-10-21
Abstract: 1,199,995. Railway braking apparatus. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. 15 Nov., 1968 [21 Dec., 1967], No. 58056/67. Heading F2F. In railway braking apparatus having deadman's means and "shut-down" means interconnected therewith so that, in a certain condition of the "shut-down" means, manual release of the deadman's means does not apply the brakes, further means interconnected with the "shut-down" means is provided so that in the stated condition of the "shut-down" means, whilst the vehicle is still in motion, the further means automatically applies the brakes. As shown in Fig. 1, an electromagnetic valve and a cut-off valve are provided in series in an additional conduit leading from the pipe A connecting the control region of the conventional emergency application valve to the conventional deadman's pilot valve in the train controller (leading to exhaust). The purpose of the invention is to ensure that the brakes are applied even if the train controller should be set to neutral while the train is in motion. (The setting to neutral of the train controller renders the deadman protection useless because, at this setting, release of the deadman's handle does not apply the brakes.) The cut-off valve is controlled by an axle-driven standstill detector so as to be open when the train is in motion. The electromagnetic valve is controlled by the train wires so that if, while the train is in motion, the train controller is set to neutral, and in consequence no current flows in either of the train wires, this valve also opens. Thereby the control region of the emergency application valve is exhausted and the brakes are consequently applied. Alternatives.-Instead of the valve having, as shown, two coils each connected to one of the two train wires, the valve may have only one coil arranged for energization from either of the train wires, diodes being included to prevent feedback between the train wires. Again, two valves may be provided in series, each controlled by one of the train wires. Again, the cut-off valve may be upstream of the other valve or valves, instead of downstream, as shown. For the embodiment of Fig. 4, a valve shown in Fig. 2 is used. The valve has a valve closure member 2 which is biased by a spring 3, acting on a piston 1 connected to the member, to permit communication between a port A and exhaust. The valve may be urged to closed position in opposition to the spring pressure by fluid pressure applied at port C. The valve may be latched in closed position, as shown, by fluid pressure applied at port B in opposition to a spring 5. In Fig. 4 the deaman's valve is connected on one side by a shut-down pipe to a pilot valve in the traction controller (this pilot valve being connectable to exhaust), and on the other side to the control region of the emergency application valve. Both ports A and B of the control valve are connected to the shut-down pipe, while port C is connected to an axle-driven stop detector. In operation, the pilot valve communicates with the exhaust in both the forward and reverse positions of the traction controller, so that in these cases, on actuation of the deadman's valve, the control region of the emergency application valve is exhausted and the brakes are consequently applied. In these cases there is no fluid pressure at B, so the latch 4 is withdrawn. Also there is no pressure at C whilst the train is moving, so the valve is open. If now the traction controller is set to neutral, and if the deadman's valve is actuated, the control region of the emergency application valve is exhausted through the deadman's valve, the shut-down pipe, and connections A and "exhaust" of the control valve; consequently the brakes are applied. Emergency application of the brakes may be prevented, when the train is stationary and the cab is vacated, as follows. When the train is at rest, fluid pressure is applied at C from the stop detector. Also, the deadman's valve is not actuated and the pilot valve communicates with exhaust, so there is no pressure at A and no pressure to open the latch at B. The valve therefore closes. The traction controller may now be set to neutral, closing the pilot valve. If now the deadman's valve is actuated (on vacating the cab) the shut-down pipe is pressurized from the emergency application valve, but the pressure cannot be exhausted at A, so the brakes are not applied. Furthermore, the pressure now operative at B causes the latch 4 to engage and hold the valve closed. The train may now be driven from another cab. In Fig. 3 (not shown), a brake controller including the deadman's valve is separate from the traction controller and is connected thereto by a shut-down pipe, which also communicates with port C of the control valve. The stop detector communicates with the latch part B. A pipe connecting the traction controller with the control region of the emergency application valve communicates with port A of the valve.