Rotary dial Strowger also filed the first patent for a rotary dial in 1891. The first dials worked by direct, forward action. The pulses were sent as the user rotated the dial to the finger stop starting at a different position for each digit transmitted. Operating the dial error-free required smooth rotary motion of the finger wheel by the user, but was found as too unreliable. This mechanism was soon refined to include a recoil spring and a centrifugal governor to control the recoil speed. The user selected a digit to be dialed by inserting a finger into the corresponding hole and rotated the dial to the finger stop. When released from this position, the dial pulsing contacts were opened and closed repeatedly, thus interrupting the loop current in a pattern on the return to the home position. The exchange switch decoded the pattern for each digit thus transmitted by stepping relays or by accumulation in digit registers.
rotary dial strowger also filed the first patent for a rotary dial in 1891 the first dials worked by direct forward action the pulses were sent as the user rotated the dial to the finger stop starting at a different position for each digit transmitted operating the dial error-free required smooth rotary motion of the finger wheel by the user but was found as too unreliable this mechanism was soon refined to include a recoil spring and a centrifugal governor to control the recoil speed the user selected a digit to be dialed by inserting a finger into the corresponding hole and rotated the dial to the finger stop when released from this position the dial pulsing contacts were opened and closed repeatedly thus interrupting the loop current in a pattern on the return to the home position the exchange switch decoded the pattern for each digit thus transmitted by stepping relays or by accumulation in digit registers