GB652625A - Improvements in or relating to electric limit switches - Google Patents

Abstract

652,625. Actuation of switches. IGRANIC ELECTRIC CO., Ltd. Dec. 2, 1947, No. 31817. Convention date, Dec. 2, 1946. [Class 38(v)] A limit switch comprises two control switches 1, 2 each controlled by a pair of cam projec- tions 4a, 5a and 6a, 7a on gears 4, 5 and 6, 7 respectively, the gears being driven through further gears 8, 9, 10, 11 inter-connected in pairs by sleeves 33, freely rotatable on a shaft 16 and urged by springs 34, 35 so that normally both engage a common pinion 3 on the reversible drive shaft 14. Upon coun- ter-clockwise rotation, Fig. 2; of cams 4a, 5a, which are driven at slightly different speeds, as by giving 5 and 6 one more tooth than 4 and 7, slots b in the cam projections 4a, 5a move into alignment with each other at one limit and are engaged by a projection 29 of a slide 26 which moves downwards to the slotted position, Fig. 2, to allow switch 1 to open. Clockwise rotation similarly releases switch 1 and at the opposite limit a further slide is raised by its cam projections 6a, 7a and opens the switch 2. The gears 4, 5 and 6, 7 may be adjusted individually relatively to the pinion 3 by axially sliding the shaft 16 in the appropriate direction whereby a key 37 thereon engaging in a slot 38 or 39 in the pinion, 9 or 10, respectively, disengages the pinion 9 or 10 from the pinion 3, and then rotating the gears and resetting the shaft 16. The latter is locked in its three axial positions by a spring clip 45 adapted to engage one of three grooves 42, 43, 44. The manner in which the limit switch is set up in relation to the controlled device is described.