![]() ![]() Hence, one input with multiple wires could be connected to one of multiple outputs, based on the receipt of a single set of pulses. While some stepping switches have only one pole (layer of contacts), a typical switch has more in the latter case, all wipers are aligned and move together. Using traditional terminology, this is a single-pole, multi-position switch. Moving from one position to the next is called stepping, hence the name of the mechanism. Like other typical rotary switches, the single terminal connects to one of the multiple terminals by rotating a contact arm, sometimes called a wiper, to the desired position. Stepping switches were widely used in telephony and industrial control systems when electromechanical technology was paramount.Ī basic stepping switch is an electrically operated rotary switch with a single (typically input) terminal, and multiple (typically output) terminals. The horizontal shaft is driven by a gear and when the Line Finder's electromagnet is energized, a flexible disc at the base of the Line Finder's brush carriage is engaged through friction to the horizontal shaft's driving disc, causing the brush carriage to rotate. In other types, such as the Strowger switch, invented by Almon Brown Strowger in 1888, mechanical switching occurs in two directions, across a grid of contacts.Īn example of a Western Electric 7A Rotary (Bird-cage) Line Finder assembly. In a uniselector, the stepping switch steps only along or around one axis, although several sets of contacts are often operated simultaneously. Code breakers at Bletchley Park employed uniselectors driven by a continuously rotating motor rather than a series of pulses in the Colossus to cryptanalyse the German Lorenz ciphers. During World War II, Japanese cypher machines, known in the United States as CORAL, JADE, and PURPLE contained them. Later, they were often used in industrial control systems. The major use of stepping switches was in early automatic telephone exchanges to route telephone calls. In electrical control engineering, a stepping switch or stepping relay, also known as a uniselector, is an electromechanical device that switches an input signal path to one of several possible output paths, directed by a train of electrical pulses. JSTOR ( November 2016) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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