Improvements in or relating to snap action electric switches

Abstract

Abstract 726,902. Press-button retractive switches. CRAIG & DERRICOTT, Ltd., and HULBERT, C. LACY-. Dec. 11, 1952 [Dec. 15, 1951], No. 29412/51. Class 38 (5) A snap switch intended to serve as a limit switch comprises a spring strip 23 loaded by a pair of tension springs 29 connected between cross-bars 28 fixed to the strip ends, the springs 29 lying one to each side of the strip (Fig. 2, not shown). The strip 23 is located by a pin 20 passing freely through a central aperture therein, one end of the pin being received in a switch operating plunger 25 and the other end being connected to a switch restoring plunger 19. The plunger 25 is slidable within a sleeve 36 itself slidable in a bush 15 and having a case-hardened head 39. A spring 42 within the sleeve 36 and acting on the plunger 25 is stronger than a spring 26 acting on the plunger 19 whereby on depression of the head 39 the sleeve 36 and plunger 25 move together and the plunger head 24 moves the strip 23 over-centre so that contacts 31 on the strip ends disengage the lower fixed contacts 33 and engage the upper contacts 33. On release of the operating force the spring 26 restores the switch. Should the head 39 be depressed sufficiently for head 21 of the plunger 19 to engage the plunger guide sleeve 17 the spring 42 permits relative movement between the parts 25, 36. To prevent vibration of the springs 29 lengths of plastic material, e.g. P.V.C. may be placed therein or therearound.

Inventors

No inventors recorded.

Bibliographic Details