The Model 191 is a push‑button start, motor driven timer with cycle progress pointer, double make‑double break snap action switch and is used to energize a load for a preset time period. The pushbutton is in the center of the time set pointer knob on the panel mounted dial. When depressed momentarily, a mechanical latch and switch is engaged, starting the motor and timing period. After completion of timing, switch 3 and 4 open, 1 and 2 close, motor stops, and timer resets to setpoint. Timer is now ready for another timing operation.