GB514558A - Improvements in switch operating mechanism for electric signalling circuits - Google Patents

Abstract

514,558. Snap-action switches. SPRAY, P. C. J. May 10, 1938, No. 13897. [Class 38 (v)] The handle A of a switch for mine signalling drives an anxle B on which is fixed a locking disc E, Fig. 3. Mounted on a spindle M is a lever L which carries loosely a locking roller G. The lever L carries a weight P just insufficient to counterbalance the lever L so that when handle A is turned clockwise, so that arm O releases lever L, the lever slowly turns to cause roller O to jam between disc E and surface H to lock the parts against further movement. This is to insure that handle A is moved quickly to the completion of its stroke. Also after one operation it is impossible to move the handle to the on position again until it has been moved back to the off position when arm O lifts the locking lever A second arm Q also lifts the lever L at the end of the operative stroke. Instead of the roller G a pawl may be used to engage teeth on disc E, and the delayed engagement of the locking means may be provided by a dashpot. The axle B carries a contact roller R, Fig. 4, which has a pin R<1> connected by springs S, S<1> to pivoted levers T, T<1>. Movement of handle A towards the on or off positions causes a cam U to move the corresponding lever T or T' to strain the appropriate spring S, or S' to move the roller to the on or off position. During the straining of the springs, the roller R is restrained by the engagement of one or other of pins R<2>, R', Fig. 5, with catches V, V' which are tripped on completion of the respective movements either by an arm W on an axle B or by a cam W<3> engaging an arm W<2>.