GB700925A - Improvements in and relating to timing devices and to clutches therefor - Google Patents

Abstract

700,925. Induction relays; retarding action of switches. ENGLISH ELECTRIC CO., Ltd. April 4, 1952 [April 5, 1951], No. 7935/51. Class 38(5) [Also in Group XXIV] A timing device (e.g. an inverse time lag relay of the induction disc or cup type) comprises primary and secondary members which may be connected by a positive clutch (see Group XXIV), the primary member being driven by a motor on the initiation of a timing cycle and the secondary member driving a timing element. In the embodiment shown a toothed clutch member 4 is driven through a pin-and-slot connection 1a, 2a from an induction disc shaft 1 and is lifted against gravity into engagement with a member 6 by magnetic means. A dnum 7 driven by the member 6, carries a contact 8 and a stop pin 9, and is initially held, by means of a weight 10 on a cord 12 attached to the drum 7, with the pin 9 in contact with a pillar 13 which is mounted on a setting knob 21. An arm 14, carried by the pillar 13, engages a toothed member 3 to position the clutch member 4 correctly for engagement with the member 6 in all positions of the knob 21. In operation the clutch is engaged and the motor driving the shaft 1 is energized simultaneously, the drum 7 being driven until the contact 8 abuts a fixed contact (not shown) whereupon the motor stops, the clutch disengages and the drum 7 is returned to its initial position by the weight 10. The clutch engaging means comprises a magnet coil 17 energized preferably by alternating current, the magnetic circuit including pieces 18, 19 embracing, but spaced from, shafts 2, 5 of magnetic material. The shaft ends 2b, 5a are enlarged and may carry shading rings 15, 16.