Patent GB-170814-A (GB)
IPC: B60T7/12
Filed: 1921-03-21
Abstract: 170,814. National Safety Appliance Co., (Assignees of Folker, H. S.). Oct. 27, 1920, [Convention date]. Fluid-pressure.-The brake pipe on a train is vented through a pneumatic stopvalve controlled by a duplex valve carried below the locomotive or tender and normally maintained closed against fluid-pressure by the action of permanent magnets, the effective field of which is weakened on passing over an active permanent magnet fixed on the track. Two valves controlled by permanent magnets, the poles of which are reversely situated, are used on the train in order that one of these valves mav always be released by the weakening of the magnetic force on the armature independently of the polarity of the track magnet. Each track magnet has associated with it an electromagnet, controlled automatically by track-circuits, which neutralize the track permanent magnet under line-clear condi. tions. Fig. 7 shows the duplex-valve F, the train stop valve D, and the driver's valve C, and the release valve E as arranged on the locomotive. Fig. 12 shows a section of the train-stop valve D, which is connected directly to the driver's valve C by a conduit 721 and to the brake-pipe by conduit 150. The double-heading release valve E is fitted on the locomotive, preferably away from the driver's cab, for the purpose of releasing the brakes after automatic operation or for putting the automatic apparatus out of action on the rear locomotive when two are used on a train. The apparatus on the track comprises a polarized permanent magnet and an electromagnet controlled by suitable track circuits and line-relays so as to be energized to neutralize the permanent magnet while a train-apparatus passes over it under danger conditions. The duplex control valve F on the train comprises two valves formed by flexible discs having a port which is closed by the plungers 46 which are attached to the armatures of permanent magnets M, M'. The valves are interposed between channels 732 in the valve cap 70, which is secured to the casing 22, and the atmosphere by way of the interior of the valve casing 22 and ports in its base. The valve cap 70 has a central hollow boss which encloses a. filter 74 which is held between the nipple 77 and a plug 76. The attraction of the armature by the pole pieces maintains the valve closed against the fluid pressure below the flexible discs. Magnetic extensions secured to the pole-pieces of the magnets M, M<1> carry inductor plates which pass over the poles of the track magnets. The inductor plates are hollow and the chambers so formed are connected to the pipe 730 co that damage to these plates causes an application of the brakes, in the same way as the opening of a valve 46 due to passage of the apparatus over an active trackmagnet. The venting of the pipe 730 releases pressure from below the piston 300 of the trainstopping valve D. This piston is normally subject to reservoir pressure below by way of pipe 728 and a restricted inlet and to brake-pipe pressure above, by way of the brake pipe 150 and parts 230<1>, assisted by a spring 320. The piston is normally raised and closes the port 310 by seating against the valve 240 on the spindle of the valve 200, which is raised as shown in Fig. 7. When the pipe 730 is vented, the piston 300 falls and the spring 320 closes the valve 200 and cuts out the driver's valve while the brake pipe is opened to atmosphere by way of the axial channel 420 and ports 430 and 330. The piston can be reset by operation of the double-heading valve 600, which consists of two plug valves operated by one lever. The valve 608, when operated, exhausts the valve chambers 733 of the control valve to atmosphere and allows the valves 46 to close. At the same time the valve 607 opens pipe 714 connected to the brake pipe to atmosphere, thus necessitating the resetting of the valves 607, 608 before the brakes can be released. In case of failure or breakage of apparatus the piston 300 may be raised mechanically by rotation of a normally sealed threaded plug 305 which serves to raise the plunger 308 and to seal the inlet passage below the piston by means of the valve 309.