GB743547A - Improvements in or relating to electromagnetic relays - Google Patents

Abstract

743,547. Electromagnetic relays. TELEFONAKTIEBOLAGET. L. M. ERICSSON. May 29, 1953 [May 30, 1952], No. 15029/53. Class 38(5) An electromagnetic relay, particularly for use in a telephone exchange, comprises a magnetic circuit formed by a frame 15, and an angle piece 2 to which a core 9 is fixed by nut 1, and with which cooperates an armature 4 mounted on pivot lugs 27 and carrying an additional member 5 that, in the attracted position of the armature, engages lug 15 projecting from the frame so as to determine the length of the air gap 26 between the armature 4 and the pole surface 10 of core 9. The additional member 5. which is optionally magnetic, rests on the armature pivot lugs 27, and, with the armature, is held in position by a spring 20 tensioned between a hook 3 fixed at the angle piece 2 and the end of a tongue 32 which projects from additional member 5 and can be bent to alter the tension and thereby the release force of the armature. A bendable tongue 16 projecting from the frame 14 forms an adjustable back stop for the additional member. At its upper end the additional member 5 is fixed to the armature 4 by a screw 7 rotation of which, by altering the distance between the armature and additional member, varies the length of air gap 26. A scale on the additional member around screw 7 may indicate the air gap length directly. Three spring assemblies, Fig. 4 (not shown), are held between the frame 14 and angle piece 2 by springs at the top of each assembly. The contacts are operated by lift strips 19 which rest on the additional member 5. To adjust the attracting current the additional member 5 may be made to move a member loaded by a spring attached to a further adjustable tongue on frame 14, Fig. 5 (not shown). The attracting and release time may be varied by changing the size of pole surface 10. The enclosing frame 14 and and angle piece 2 form a magnetic screen.