Not 100% certain, but assume that when the trolley pole hits the = contactor on the overhead the electrical connection to the switch motor = in the pavement is completed. When the button on the dash is pushed in, = AC is sent in one direction to the switch motor and the switch changes = to the curve, or remains curved. When no action is taken by the = operator, AC is sent in the other direction and the switch returns to = the straight, or remains straight. Very similar to electric switch = motors on our own model layouts.
-- Roy