Color Position B&O and Position Pennsy Signals
In the 1920’s, the Pennsylvania Railroad replaced their semaphore signals with a position light type supplied by Union Switch and Signal Co. Although there were several variations in the basic signal employed seven amber lamps, the center one being “on” for each on the three indications. In the mid 1930’s, the B&O decided to replace their semaphore signals with a color position type from General Railway Signal Company. The basic head employed six lamps – two each of red, yellow and green. The B&O system also employed lunar white marker lights for speed indication.

Pennsy and N&W Signals
ISS manufactures the basic seven lamp PRR signal head exactly to HO scale using light yellow 3 mm diameter LEDs. The head can be mast mounted or used on signal bridges. In both cases it was mounted in front of the mast. The ISS signal controller SC-2 will operate these signals using lower value current limiting resistors. The Pennsy also used lower quadrant (or lower head) signals to indicate various speed and track conditions. ISS has three types of lower quadrant signals available: