GB755206A - Improvements in or relating to electric switching keys - Google Patents

Abstract

755,206. Retractive switches; switches held set and freed mechanically. STAND DARD TELEPHONES & CABLES, Ltd Dec. 10, 1954, No. 35794/54. Class 38(5) A switching key comprises a framework with one closed end in which is journalled a cam-barrel and an operating knob, spring members on the framework co-operating with flats on the barrel for holding it in certain positions, spring contact pile-ups arranged for operation by the barrel, and a stop on the framework co-operating with the cam periphery so as to allow certain axial and/or rotary movements of the barrel, variations in the shape of the barrel thereby producing various combinations of turn and push actions Normally, the barrel 12 is out of engagement with plungers 24, 25 so that contact pile-ups 4, 5 are not operated. Rotation of the barrel through 90 degrees clockwise in Fig. 1 causes a flat 22 thereon to operate plunger 24, the barrel being held in each position by springs 6, 7 engaging sloping flats 19, 20 on the barrel. The barrel may be moved axially in either end engular position-to cause operation of plunger 25 by a sloping surface 23 on the barrel. Axial movement in any other angular position, and rotary movement in any other axial position, are prevented by a stop 15 (with a step 16) and recesses 26, 28 and a flange 27 of reduced diameter in the barrel The springs 6, 7 return the barrel to its normal axial position by acting on the sloping surfaces 19, 20, but in Fig. 5, the barrel is retained in the operative position by engagement of the springs 6, 7 in a groove 29. The axial action may be stopped by omitting notch 26 and/ or 28 and the rotary action stopped by omitting to cut the flange 27. A light signal may be given by a translucent member passing through the barrel in a manner similar to that of Specification 620,465.