Abstract: A relative translation of a first cam with respect to an electrical switch is established between first and second relative positions, whereby the electrical switch is established in a selected one of first and second states. A second cam has first and second detent positions respectively corresponding to the first and second relative positions. A pivot pivotally mounts the second cam, and a pneumatic impulse is generated for establishing the relative translation of the first cam with respect to the electrical switch. A fixed cam follower engages the second cam, whereby, in response to the impulses, the relative translation is established, a relative movement is established between the second cam and the fixed cam follower, the second cam effects a pivotal movement about the pivot, and the second cam is detained by the cam follower in one of the detent positions. Thus successive ones of the impulses control movement of the electrical switch alternately between the first and second states.