All contact surfaces and switching mechanisms are located inside the rotary switch where they are protected from outside elements. This enclosure also makes the rotary switch explosion proof.
A circuit is completed by a shorting member that bridges a separate input contact and output contact at each switch position. This allows circuit versatility and forces the current to make and break at two points simultaneously, dividing the load, heat, and wear.
As rotation to the next position is begun, a spring in the advance mechanism is compressed, storing energy that is released all at once as rotation continues. This rapid advance produces a quick-break, quick-make that is virtually independent of the speed of the actuator.