Strowgers

Strowger, also known as the Strowger switch or stepper switch, refers to a type of electromechanical telephone exchange switch invented by Almon Brown Strowger. This invention revolutionized automatic telephone switching, moving away from manual operators connecting calls. The Strowger system worked by using a series of rotary switches that would step through a sequence of contacts based on electrical pulses transmitted from the caller's telephone dial. Each digit dialed generated a specific number of pulses, which would move the switch to the corresponding line or connection.

The initial Strowger switch was a single-motion stepper. Later iterations, like the two-motion stepper, were developed to handle more complex connections and larger exchanges. The core principle involved a central shaft with a wiper that rotated and lifted to connect with different contacts arranged in a circular pattern. This allowed for the automatic routing of phone calls without human intervention. Strowger's motivation for developing the automatic exchange was reportedly due to a perceived bias from manual operators. The technology was widely adopted in telephone systems around the world throughout the early and mid-20th century. While eventually superseded by electronic and digital switching systems, the Strowger switch remains a significant milestone in the history of telecommunications.