Chapter 11 – Switch mechanisms

Publisher Summary This chapter focuses on the operating mechanism of manually operated switches. Manual operation of a switch can vary from gentle pressure to violent prodding of a push button or fast flicking of a toggle lever. The actuating mechanism must be strong enough to withstand the extremes of treatment that are likely, but must not, as far as possible, allow such treatment to affect the contacts. Modern switches for supply use do not rely entirely on the movement of the operator to determine opening or closing speeds. These switches consists of two parts, the contact part and the actuating part. The contact part consists of a spring-loaded toggle, which has two stable positions. In any other position of the toggle, apart from a precariously balanced central position, the spring action ensures that the moving contact is in one stable position or the other. This spring also determines the force with which the contacts are held together. The actuating portion of the switch, in its motion, displace part of the spring toggle until the spring action flips over the switch.