GB389959A - Improvements in or relating to electrical indicators - Google Patents

Abstract

389,959. Electromagnetic relays. ERICSSON TELEPHONES, Ltd., 67, Kingsway, London, and NEWELL, G. R., Ericsson Telephone Works, Beeston, Notting- ham. Feb. 2, 1932, No. 3065. [Class 38 (v).] Indicators.-In a combined electromagnetic indicator and relay of the type used in telephone exchanges, the armature is maintained in the operated position upon de-energization of the magnet by a locking member which has no retarding effect upon the operation of the armature. Fig. 1 shows an indicator similar to that described in Specification 167,522, [Class 40 (i), Electric signalling systems &c.], wherein the armature and indicator flap assembly comprises a channelshaped member D which pivotally supports the armature A and indicator B interconnected by a stiff wire C. The armature is operated by a coil wound on a core and contained within an iron shell S, the armature being normally maintained in its retracted position by a helical spring contained within the end of the core and adapted to co-operate with disc DS on the armature. The armature assembly is fixed to the shell S which is supported on a front plate FP in such a manner that a protecting cover, Fig. 3, may be slipped through a hole in the front plate and over the end of the shell. The cover is provided with a label LB covered by a window W and arranged to form an O-shaped aperture for revealing the indicator flap B. The armature is adapted to be locked in the operated position by a pivoted two-armed lever LM the upper arm of which in the retracted position of the armature, rests against the armature. When the armature is attracted the lever LM turns about its pivot under the action of gravity into a position such that the ,upper arm is substantially at right angles to the armature and holds the latter looked. During this movement the lower arm moves freely in a slot T2 in a member N operable by a push button PB which when depressed restores the lever and allows the armature to move to its normal position. The lower arm of the lever may be insulated in order that restoration may be effected by the insertion of a plug in a jack. The armature operates contacts mounted in the front face of the coil, the insulated boss I being provided for that purpose. The inertia of the locking member produces a. time lag between the operation of the armature and locking thereof, thus preventing permanent operation in response to short pulses of exciting current.