GB296553A - Improvements in pneumatically operated door control systems and apparatus - Google Patents

Abstract

296,553. Peters & Co., Ltd., G. D., Jones, T. G., and Hockley, H. R. Sept. 1, 1927. Operating doors electrically and pneumatically. and by treadles and the like.-In a pneumaticallyoperated door control of the kind in which safety is ensured by an interlocking of the system with the brakes and comprising a switch that is actuated automatically to close an electric circuit when the brakes are applied, each door is provided with a magnetic switch that controls the door operating mechanism and the solenoid coil of which is energized by the closing of an electric circuit controlled by the switch when the brakes are applied, the construction of the switch being such that the handle thereof is held normally by a spring in the inoperative position and when the handle is moved into an operative position it will be maintained in this position if the solenoid is energized until the brakes are released, the handle of the switch being then returned to its inoperative position by its spring, further applications of the brake being possible without influencing the door control mechanism unless the switch handle be again moved into its operative position when the brakes are applied. A doublepole switch for this purpose is shown in Figs. 1 and 5, the lay-out of the wiring and piping being represented in Fig. 7 as applied to an omnibus having door engines 20, 21 for the front entrance and rear exit doors. The switch comprises a solenoid 1, the movable plunger 2 of which carries a flanged extension 3 engaging the end of a spindle 5 carrying an insulated drum 6 with contact strips 7 adapted to engage spring contact fingers 8. The upper end of the spindle 5 is shape-d to receive an operating handle, a helical torsion spring 10 being provided to tend to maintain the spindle 5 in its mid and inoperative position. A pin-and slot connection 12, 13 allows the plunger 2 to move longitudinally under the action of the spring 4 in one direction, and by the energization of the coil 1 in the other direction. When the brakes are applied and the coil 1 is energized, rotation of the spindle 5 by its handle against either of the stops 11 brings a slot in the flange 3a over a fixed pin 15, and, the handle being then released, the switch is maintained in position, with a contact strip 7 making contact with a pair of contacts 8, by the action of the solenoid drawing the plunger 2 so that a recess in the flange 3<a> engages one or other of the pins 15. The switch may be released manually by raising a pin 16, when the spindle 5 returns to its mid-position by the action of the spring 10. In the diagram, Fig. 7, the battery 30 is connected through a wire 31 to a passenger emergency switch 32 and to the electro-pneumatic valve 23 of the front entrance door, and to a fixed contact of the driver's pneumatic switch 1; also by a wire 34 to the coil 23 of the electropneumatic valve 23 of the rear exit door, @ one of the fixed contacts of the conductor's magnetic switch, and through a treadle switch 22 to the other fixed contact of the conductor's double-pole switch. The positive pole of the battery is also connected through the air-operated switch 26 to one end of the coil of both the driver's and conductor's magnetic switches by wires 35, and to the moving contacts of said switches. The piping system includes the door engines 20, 21, their valves 23, an air-operated switch 26 and a threeway brake-interlocking valve 27. When the driver applies the air brakes' the switch 26 is operated to close the contacts thereof so that the solenoids 1 of both magnetic switches are energized If the handles of these magnetic switches are now moved into appropriate positions, the contacts 7. 8 will be closed to complete the circuits of the valves 23 of the door controlling mechanism and the handles will be held in the set positions until the driver releases the air brakes, whereupon the switch 26 will open the circuit of the magnetic switch solenoids and the handles will at once be returned by the springs 10 to their inoperative positions; further applications of the brake can then be made, as previously stated. A diagram is also given of an arrangement in which the driver or conductor may control both doors.