Operation of the RailKing 7-light (position light) block signal #30-11013
Railroad Position light signals - prototype
Position light signals use rows of 5.375 inches (13.65 cm) diameter lamps to simulate the positions of an upper quadrant “semaphore” blade. Position lights were developed by A.H. Rudd, Superintendent of Signalling of the Pennsylvania Railroad (PRR). They were introduced in 1915 as a replacement for “semaphore” signals on the Main Line between Paoli and Philadelphia due to visibility problems caused by the new overhead electrification project. The signal uses rows of three lamps, surrounding a common center. ach position lamp unit is equipped with a 12 volt, 6 candlepower bulb mounted in front of a parabolic mirror that increases the relatively weak bulb's intensity. A light yellow tinted conical glass with frosted tip was chosen, as this color was determined to have the highest visibility under fog conditions based on empirical studies at Corning at that time.
Vertical position – Proceed
Diagonal position – Caution
Horizontal position – Stop
RailKing 7-light block (position light) signal #30-11013
Blue wire – when connected to 10 to 18 volts the lower single lamp is on.
Green wire – when connected to 10-18 volts the diagonal lamps are on (Caution) and maintained for 10 seconds. After 10 seconds the vertical lamps are on (Proceed).
Red wire – when connected to 10 to 18 volts the horizontal lamps are on (Stop).
Black wire – connected to common.
