GB1200262A - Improvements in or relating to timer for operating electric switches - Google Patents

Abstract

1,200,262. Time switches; mechanical interrupters. MAGNETIC DEVICES Ltd. 28 March, 1969 [29 March, 1968], No. 15272/68. Heading H1N. A rotary interrupter or cycle timer comprising a motor 10 driving a cam-shaft 13 via reduction gearing and clutch 12 is provided with means for returning the cams (not shown) to a datum position at the end of a cycle, or when required, or upon failure of the power supply. A housing 15 mounted on an arbor 16 freely rotatable on shaft 13 surrounds a ratchet wheel 14 secured to shaft 13 and carries a pawl 18 pivoted at 17 to engage the wheel 14 under action of a spring 19. A flat coil spring 20 is attached at its inner end to arbor 16 and at its outer end to a support pillar 21 and tends to rotate the housing, and hence wheel 14 and shaft 13, in the direction opposite to the drive from motor 10. When a lever 30 is urged to the position shown in Fig. 1 (against the action of a spring 33) the clutch 12 is engaged and the motor 10 drives shaft 13 and cams (not shown) which operate a number of electric switches in sequence. The wheel 14 drives housing 15 (via pawl 18) and spring 20 is wound up until after almost a complete revolution of housing 15 a recess 29 is aligned with a projection 27 on a lever 25, whereupon a spring 28 urges the projection 27 into the recess 29 to disengage the pawl 18 from wheel 14 and hold the housing 15 against the return force of spring 20. The cam-shaft 13 continues to be driven without further action on housing 15. When lever 30 is released the clutch 12 is disengaged and lever 30 abuts lever 25 to remove the projection 27 from recess 29-the spring 33 being stronger than spring 28. This releases the housing 15, and lets pawl 18 re-engage wheel 14; spring 20 then rotates the housing 15, wheel 14 and cam-shaft 13 back to a datum position determined by engagement of a pin 40 on wheel 14 with the end of a pivoted arm (41, Fig. 2, not shown) which is spring-loaded to allow forward rotation of pin 40 past it but to block its return. The lever 30 may be operated (against spring 33) by a solenoid (34, Fig. 4, not shown) in which ease failure of supply de-energizes the solenoid and automatically resets the camshaft 13. The solenoid may be energized over a switch actuated by one of the cams on shaft 13 so that resetting occurs on completion of a sequence cycle.