As a part of its experimental program for development of electric locomotives the PRR Motive Department built eight 2-B-2 (4-4-4) electric locomotives and designated them as O-1. They were built in the PRR's Altoona, PA shops in 1930 and 1931.
These eight locomotives were built to experiment with various manufacturers components and to try different ratings of traction motors and various gear ratios. Three of the O-1s were built with General Electric equipment, three had Westinghouse equipment and two had Brown-Boveri components. The locomotive drivers were driven by twin motors through geared quill.
Two of O-1s (road numbers 7850 & 7851) were designated as Class O-1 and were built with four 500 HP traction motors and a gear ratio of 31:91 which allowed a continuous speed of 56 mph and a continuous tractive effort of 13,200 lbs; two (road numbers 7852 & 7853) were designated as Class O-1a and were built with four 625 HP traction motors and a gear ratio of 36:103 which allowed a continuous speed of 63 mph and a continuous tractive effort of 14,900 lbs; two (road numbers 7854 & 7855) were designated as Class O-1b and were built with four 550 HP traction motors and a gear ratio of 49:114 which allowed a coninuous speed of 46 mph and a continuous tractive effort of 17,800 lbs and two (road numbers 7856 & 7857) were designated as Class O-1c and were built with four 625 HP traction motors and a gear ratio of 31:91 which allowed a continuous speed of 63 mph and a continuous tractive effort of 14,900 lbs.
All of the O-1s were equipped with roller bearings and top speeds of 90 mph could be reached. The O-1s always ran in pairs, but sub-classes were never mixed. The O-1s proved to be too light for general use and the 4-4-4 wheel arrangement was slippery while starting trains. They were used in passenger service and except for hauling the "Susquehannock" between Philadelphia and Harrisburg during the World War II they were used on relatively light Lehigh Valley passenger trains between Penn Station and Hunter Tower in Newark. They spent the last few years of their existing around Sunnyside Yard and New York area as Utility locomotives mostly hauling empty passenger cars. All of the O-1s were scrapped by the mid 1960s.
|Class||Road numbers||Traction Motors||Total HP||Gear Ratio||Tractive Effort|
|O-1||7850-7851||4 @ 500 HP||2000 HP||31:91||13,200 lbs @ 56 mph|
|O-1a||7852-7853||4 @ 625 HP||2500 HP||36:103||14,900 lbs @ 63 mph|
|O-1b||7854-7855||4 @ 550 HP||2200 HP||49:114||17,800 lbs @ 46 mph|
|O-1c||7856-7857||4 @ 625 HP||2500 HP||31:91||14,900 lbs @ 63 mph|
|Wheel Arrangement:||2-B-2 (4-4-4)|
|Heigth:||15'-0" with pantographs down|
|Truck Wheels:||36" dia.|
|Weight on Drivers:||150,000 lbs*|
|Locomotive Weight:||300,000 lbs*|
|Line Voltage:||11,000 Volts, 25 Cycles (HZ) AC|
|Traction Motors:||see chart|
|Total HP:||see chart|
|Gear Ratio:||see chart|
|Tractive Effort:||see chart|