Patent GB-254347-A (GB)
Title: Improvements in or relating to apparatus for operating and controlling doors by fluid pressure
IPC: B61D19/00
Filed: 1924-12-23
Abstract: 254,347. Peters & Co., Ltd., G. D., Hockley, H. R., Palmer, B. W., Hewitt, L. B., and Metropolitan Electric Tramways, Ltd. Dec. 23, 1924. Operating doors electrically and pneumatically.-For operating and controlling the doors of electric tramway cars and other vehicles the valves controlling the supply of compressed air to the door motors are controlled by electromagnetic devices comprising high-voltage and low-voltage magnets which are energized respectively by the traction current and by regenerative current from the motors when the car is coasting and traction power is cut off, the arrangement being such that the doors are maintained closed so long as the car is travelling above a predetermined low speed (e.g., three miles per hour), at which the low-voltage magnet ceases to be energized. The system is shown diagrammaticallv in Fig. 1, embodying the electromagnetic valve device shown in Fig. 2 for maintaining the doors closed until the car speed is reduced sufficiently, all the pipes under air pressure from the reservoirs 2 and 3 being shown with a centre line. A slide valve 50 is movable with a piston 52 by a spring 67 on one side and when subjected on the other to compressed air supplied through a pipe connection 79. A casing 56 contains coils 54 of which 54<c> is the high voltage coil and 54<D> the coil supplied with regenerative current when the car is coasting. Normally when the car is travelling, one of the cores 55 is attracted and the rod 63 connected with the cross-piece 62 keeps the valves 66, 65 lifted to close the exhaust through 77 and open the valve 76, compressed air passing through the inlet 75 to move the piston 52 and valve 50 to the left-hand side. When the regenerative current is not sufficient to keep the core in the raised position, the piston is put to exhaust and the slide valve 50 moved to the right by the spring 67 into a position to permit of the doors being opened. The system is supplied with compressed air from a compresor 1 a reservoir 2 and a main supply pipe 5 communicating with the driver's control valves 7 located at opposite ends of the vehicle. Branch pipes 9 connect the pipe 5 with ports 10 of the treadle valves 11, a pipe 12 leads to a port 13 of the slide valve 50, and pipes 9, 15 lead to the motors 16 for operating the entrance doors B and exit doors A. The ends of the pipe 5 are connected with ports 17 of the dead man's valve devices 18 at each end of the vehicle. The valve device 14 has a port 19 connected by pipes 20 to ports 21 of the driver's control valves 7 and a port 22 connected by a pipe 23 to a port 24 of an emergency valve device 25 of the switch 26. The port 22 is also connected by a pipe 23 to a port 27 of the dead man's valve 18 at one end of the vehicle, which valve is opened to exhaust through the port 29, pipe 30 and ports 31, 32. The brake cylinder 33 is connected through a pipe 34 with the emergency valve device 25, a port 43 of which leads through a branch 42 to the train pipe line 40. In order to provide for the desired rapidity of action of the door control apparatus there is provided an automatic accelerating valve 81, so that when the valve chamber pipe 23 is charged with air from the reservoir 2 as the driver grips the dead man's handle the pipe 23 is at the same time placed in communication with a pipe 80 leading from an emergency reservoir 3. The emergency valve device 25 for controlling the air-operated switch device 26 is similar to the emergency valves employed in compressed-air brake-operating apparatus used on tramcars. The door motors each comprise two pistons connected by a rack 126, Fig. 14, that gears with a quadrant 127 on a shaft 128 with levers fixed to its ends, one of the levers being connected by a link mechanism to the door. The supply of compressed air to and from the cylinder 130 is controlled by a disc valve 131, on the stem of which is an operating arm 133 articulated to a valvepuller 134. The treadle valves 11 are similar in construction to the slide valve 50, piston 52 and control valves 65, 66 of the electromagnetic valve device 14, Figs. 1 and 2. The control system operates as follows :-Before starting, the driver sets the manual control valves 7 as shown in Fig. 1, the brakes are released, the handle of the front dead man's valve 18 is grasped, and current is supplied to the car motors. Compressed air is then supplied to the valve-pullers 134 of all the door motors 16 to maintain the doors closed as the car starts, the high-voltage coil 54<c> of the valve device 14 having been energized to move the slide valve 50 into this operative position. When the driver shuts off power and the car commences to coast, the coil is de-energized by the breaking of its contact with the controller drum and contact is made so that a regenerative current flows through the low-voltage coil 54<D>; this maintains the doors closed until the speed has been reduced to two or three miles per hour as the car is gradually brought to rest by the driver applying his brakes. The coil 54<D> is then deenergized, the controlling pin 63 is lowered, and the main air supply to the device 14 through the port 13 is cut off, the pipe 23 being directly connected to the pipe 20. At this stage, if passengers congregate on the appropriate treadle plate of a valve 11 and the driver releases his grip of the dead-man's handle, the air supply port 17 will be closed and the pipe 23 through the pipe 30 and rear dead man's valve put to exhaust. These conditions provide that the valve pullers 134 and feed pipe 141a of the near side entrance and exit doors are exhausted and these doors then open. The exit doors close when the pasengers have left the car and allowed the treadle plate to rise, and the entrance doors close when the driver again grips the dead-man's valve and re-charges the pipe 23. During a block in the traffic, the doors are maintained closed so long as the driver grips the dead-man's handle. At the end of the journey, the driver moves the control valves 7 for a reverse direction to set the system for operating the doors at the other side of the car. In order to avoid passengers being trapped in a closed car in the case of a collision, the feed pipe 150 to the supply pipe 5 is placed in an exposed position so as to be fractured.