Cam timer is an electromechanical system for controlling a sequence of events automatically. An electric motor drives, through a reduction gearbox, a shaft on which is arranged a series of cams. Associated with each cam is one or more switches. The motor rotates at a fixed speed, and the camshaft follows, usually very slowly. Indentations or protrusions on the cams operate the switches at different times. By arrangement of the cams and switches, complex sequences of opening and closing switches can be made. The switches then operate different elements of the controlled system. The most common use for cam timers is in automatic washing machines, where they are used to drive the washing sequence according to a preprogrammed pattern.