GB243478A - Improvements in or relating to automatic locks for doors, particularly the doors of lifts and like shafts - Google Patents

Abstract

243,478. Elliston, E. R. Sept. 24, 1924. Catches yielding to pull and pressure.-A pin 2 on the hinged or sliding door of a lift well, escalator, train, &c. co-operates when the door is closing with two spring-controlled forked or notched levers 10, 11 on the door frame A which form a yielding catch to close and secure the door and to control an electric circuit such as the main circuit in the case of a lift. The levers may be locked by the movement of a lift cage. The levers, latch and switch are mounted as a unit on a base 1 as shown in plan in Fig. 3 and in elevation in Fig. 2. As the door closes, Fig. 4, the pin 2 engages the forked ends of the levers 10, 11 which are pivoted at 5 and are urged towards either extreme position by springs 12, 13 so as to snap over when past their dead centres. The lever 11, loose upon the spindle 5, forces the door home and holds it closed, whilst the lever 10, fast on the spindle 5, closes the switch 7, 8. When the lift cage is moved, a cam C disengages an arm 19 on a shaft 17, allowing the shaft to turn under the action of a spring 17<a>, bringing a latch arm 16 on the shaft into position to lock the levers 10, 11, as shown in Fig. 2, but with sufficient play to allow for warping or springing of the door. The parts are arranged so that when the switch is closed the levers are in position to be locked by the latch, and so that the play between the levers and the latch does not break contact at the switch.