The essential parts are shown in the adjoining illustration. A push A is connected to a spring B. Underneath the push is a smaller spring contact C, and at the side opposite 13 is another contact D. B, C, and D each have terminals, not necessarily in the form sketched. By these terminals the connections required may be made. In the standing position B and D make contact, but by pressing A the circuit is made by way of B and C.

Construction of Double-contact Push.