Wire spring relay

[citation needed] They were used extensively in markers, which were special purpose computers used to route calls in crossbar switch central offices.

Wire spring relays were primarily manufactured by the Western Electric Company for use in electromechanical telephone exchanges in the Bell System.

Manufacturing of wire spring relays greatly declined in the late 20th century due to the introduction of digital electronic switching systems that used them in very small numbers.

The contact points are made from small blocks of precious metals, such as palladium, which are spot-welded to the wire springs.

A moving contact consists of two wires projecting out of the base of the relay, bent slightly inwards in order to exert pressure against the armature.

For the stored program control exchanges of the early 1970s, many relays were made with steel cores that remained magnetized after current ceased to flow in the winding.

When output wires are fed back as inputs, the result is a feedback loop or sequential circuit that has the potential to consider its own history.

They were used in conjunction with wire spring relays, for example to store digits for sending to other crossbar switching offices.