GB783401A - Improvements in and relating to an electric snap-action switch - Google Patents

Abstract

783,401. Snap-action switches; momentarycontact switches. LAURE, M. H. H. Feb. 20, 1956 [Feb. 28, 1955], No. 5240/56. Class 38 (5). A switch comprises a dead-centre spring which gives a contact lever a stable position on each side of the dead centre, a reciprocable actuator and an intermediate member so arranged that during a first part of the travel of the actuator the member acts on one end of the contact lever to move it in one direction across dead-centre, and during the second part of the travel the member acts on the other end of the contact lever to pivot it in the other direction across dead-centre, the spring when released causing the actuator and the intermediate member to return to their initial positions whilst leaving the contact lever in the position reached at the end of its second movement. In one form (Figs. 1, 4 and 5), the contact lever 19 is pivoted at 20 and is pivotally connected at 22 to the intermediate member 23 which is acted upon by the dead-centre tension spring 25 having a fixed point n. The member 23 has a shaped end 33 co-operating with a recess 30 in a push-button 24, depression of which to the Fig. 4 position causes counter clockwise movement of lever 19 to engage contacts 21 with fixed contacts 10 with a snapaction. Further movement of the button 24 to the Fig. 5 position causes the lever 19 and member 23 to tilt clockwise to re-open the contacts with a snap-action, the spring 25 restoring the button 24 and member 23 when the button is released. The partsi, j of the button 24 may be differently-coloured so as to serve as indicators. In another form (Figs. 6, 7), the contact lever 36 is connected at 39 to a member 38 which has a slideway formed by parts 40, 41 and engaging a collar 42 on the button 43, and the member 38 is acted upon by a torsion spring 47. The actuator may comprise a pivotable member, e.g. a cam, acting on a push-button, and the spring may be a compression spring.