GB1097014A - Improvements in or relating to electric switches - Google Patents

Abstract

1,097,014. Cam-operated switches; retractive switches. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. March 26, 1965 [March 26, 1964], No. 12975/64. Heading H2B. A push-button switch has a hollow knob 17 provided with an opposed pair of limbs 18, each having a protruberance 25 resiliently interlocked in an indentation in a slot (23 or 24, Fig. 3) inside a hollow spring-loaded carriage 20 to removably attach knob 17 thereto, carriage 20 being slidable to actuate contact sets. A fixed escutcheon 15 is provided with spring clips 63, 64 to facilitate mounting in a panel aperture. To dismount the switch, knob 17 is first removed by a tool inserted in opposed bores 68, and then another tool is inserted in four ventilatory slots 66, 67. Carriage 20 has pivotally mounted thereon and sliding therewith an arm 53 having at its free end a pin 54 constrained to travel in a heart-shaped fixed stepped cam track 42. Two contact sets 35, 36 are provided, each set comprising two changeover sets each of which has three leaf springs 37, 38, 39. Contact 38 of each set has an arm 71 engageable by a wedge and shaped finger 21 on carriage 20. A tensioned retaining spring 57 mounted on arm 53 has its ends shaped around a third pair of wedges 21. Carriage 20 slides on a tubular fixed lampholder 27, and a lamp illuminates the knob 17 internally, said knob being translucent. A spring 31 urges carriage 20 to the left until bars 33, 34 thereon abut the part 15. In Figs. 1 and 2, knob 17 and carriage 20 are fully retracted. When knob 17 is fully depressed, this movement being limited by a shoulder 69 inside carriage 20 abutting the end of lampholder 27, arms 71 on contacts 38 ride up the slopes of wedges 21 thus causing contacts 38 to change over from contacts 39 to contacts 37. During this depression, pin 54 has travelled from base point A of track 42 to a point D, being constrained to move anticlockwise by a step at point A. As the knob 17 is released it partially retracts and pin 54 travels to point E, and the switch is latched in this position, contacts 38 still making with contacts 37. On the next full depression and immediate release of knob 17, pin 54 travels back to A via points F, G, being constrained to move in this direction by a step at E; knob 17 and carriage 20 return to their fully retracted position, and during this retraction contacts 38 change over from contacts 37 to contacts 39. In a modification, arm 53, spring 57 and track 42 are omitted, and each spring set 35, 36 accommodates a further pair of " make " contact springs on ledge 52.