GB702218A - Improvements in and relating to electromagnetic switches - Google Patents

Abstract

702,218. Automatic exchange switches. TELEPHONE MANUFACTURING CO., Ltd. Nov. 30, 1951 [Dec. 1, 1950], No. 29487/50. Class 40 (4) An electric connector switch comprises a member adapted to be stepped by the pulsing of a polarized electric motor and arranged in each position to close or open a set of contacts associated with that position. The motor 24 which is of the type described in Specification 672,140, [Group XXXV], has a rotor having two stable states of equilibrium which it is prevented from reaching as described' below. On being alternately impulsed with currents of opposite polarity the rotor reciprocates to produce a corresponding motion in the lever 33 which is fixed to the rotor spindle. The lever 33 carries a pin 34 slidable in a groove 31b of the pawl arm 31 which is pivoted at 32. The pins 31a of the pawl 31 are arranged to step the ratchet wheel 30 whose teeth are separated by a space having an elongated channel 30a in which the pawl pin resides at the end of the stroke to hold the ratchet firmly in position. The throw of the pawl and therefore also of the rotor is limited by the engagement of the pawl pins with the bottoms of the channels 30a. The distance of the pin 34 from the spindle of the rotor is readily adjustable so that the throw of the rotor may be adjusted to suit different impulsing speeds. The ratchet wheel 30 drives a splined shaft 10 carrying cams 10a ... 10g. Cams 10b ... 10g are staggered and operate contact sets 12 ... 17 successively during one half-revolution and sets 18 ... 23 during the other half-revolution. The contact sets 12 ... 21, 23 are made at every other movement of the pawl and at the intervening movements the interrupter contacts 11 are closed. The normally-made contacts. 22, broken by operation of the cam 10f, which is arranged to occur slightly early, i.e. so that the contacts are opened by the same pawl stroke which opened the preceding contact set. This may be arranged by a slight angular rotation of the cam 10f or preferably by a slight forward displacement of the spring set.