GB478662A - A time-controlled electrical switch - Google Patents

Abstract

478,662. Time switches. I. G. FARBENINDUSTRIE AKT.-GES. July 22, 1936, No. 20301. Convention date, Aug. 14, 1935. [Class 38 (v)] A switch specially adapted to close the circuit to a photographic printing device for a predetermined time comprises contacts in an evacuated container 1, a tilting operating rod 2 for the contacts and a weight-controlled timing device for actuating the rod 2. To operate the device a weight 4 on a rack 3 is first raised to the position shown. During this movement a ratchet wheel 10 driven by the rack 3 slips idly past a pawl 9. The weight is then allowed to fall' and the rack drives through the ratchet and pawl device 9, 10, a wheel 6 in gear with escapement mechanism 7, 8. so that the weight and rack fall at a predetermined rate. At the beginning of this movement a pin 11 on the rack 3 moves away from a lever 12 which moves to the left about its pivot 12b and withdraws a pin 12a from the rod 2 allowing the contacts of the vacuum switch 1 to close. The rack now falls an adjustable distance determined by the setting of a cam 13 provided with a dial plate. At the end of this distance a pin 16b on a lever 16 pivoted at 16a on the rack strikes the cam. The lever 16 is rotated and presses a lever 19, pivoted at 19b, to the right so as to release a pawl 22 which falls so as to engage a ratchet wheel 23 and stop the clockwork. The end 22a of the pawl 22 also engages the pin 12a and rotates the lever 12 so that it presses on the rod 2 and opens the vacuum switch. In resetting a pin 24 on the rack lifts the pawl 22 into the original position..