Pennsylvania Railroad class O1

PRR O1
PRR official photo of #7850
Type and origin Power type electric Builder PRR Altoona Works[1] Build date 1930–1931 Total produced 8
Specifications Configuration: ​  • Whyte 4-4-4  • AAR 2-B-2  • UIC 2'B2' Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Leading dia. 36 in (914 mm) Driver dia. 72 in (1,829 mm) Trailing dia. 36 in (914 mm) Wheelbase 40 ft (12.19 m) (overall) 10 ft (3.05 m) (fixed)[1] Length 52 ft 8 in (16.05 m)[2] Width 10 ft 6 in (3.20 m)[3] Height 15 ft (4.57 m) (over locked-down pantographs)[2] Axle load O1, O1b, O1c: 75,000 lb (34,000 kg)[3] O1a: 78,000 lb (35,000 kg)[2] Adhesive weight O1, O1b, O1c: 150,000 lb (68,000 kg)[3] O1a: 156,000 lb (71,000 kg)[2] Loco weight O1, O1b, O1c: 300,000 lb (140,000 kg)[1] O1a: 309,400 lb (140,300 kg)[1] Electric system/s 11 kV 25 Hz AC Catenary[1] Current pickup(s) Pantograph Traction motors 4× (2 per axle), power output each - O1: 500 hp (370 kW); O1a, O1c: 625 hp (466 kW); O1b: 550 hp (410 kW)[1] Transmission AC current fed via transformer tap changers to paired motors driving geared quill drive[1] Train heating Steam generator Loco brake Air Train brakes Air Safety systems Cab signalling
Performance figures Maximum speed 90 mph (140 km/h)[1] Power output O1: 2,000 hp (1,500 kW); O1a, O1c: 2,500 hp (1,900 kW); O1b: 2,200 hp (1,600 kW)[1] Tractive effort O1: 28,500 lbf (127 kN); O1a, O1c: 37,500 lbf (167 kN); O1b: 35,000 lbf (160 kN)[1] Factor of adh. O1: 5.26; O1a: 4.16; O1b: 4.29; O1c: 4.00
Career Operators Pennsylvania Railroad Class 7850–7857 Retired 1948–49 (6), 1961 (2) Disposition All scrapped

The Pennsylvania Railroad's class O1 comprised eight experimental boxcab electric locomotives^[4] built in 1930 and 1931.^[1] They were built in preparation for the New York to Washington Electrification project.^[5] They had the wheel arrangement classified as 4-4-4 in the Whyte notation (UIC: 2'B2'; AAR: 2-B-2). Although successful, they were not powerful enough for the railroad's increasingly heavy trains. For production, the PRR chose to concentrate on the P5 class, effectively an enlarged and more powerful version of the O1 with an additional pair of driving wheels.

The eight locomotives were divided into four sub-classes — O1, O1a, O1b, and O1c.^[6] Each sub-class was fitted with a different combination of traction motor power output and drive gear ratio. In addition, three O1 locomotives were fitted with General Electric equipment, three with Westinghouse, and two with Brown Boveri. The O1b locomotives used a Buchli drive between the traction motors and the driving wheels. Double traction motors [de] were used, with two motors geared to each axle.

They were generally employed in pairs by sub-class, generally on short-distance passenger trains between Newark, New Jersey and New York City's Pennsylvania Station. During World War II they were used on the "Susquehannock" between Harrisburg, Pennsylvania and New York City. Later in life, they were used for transfer work around Penn Station and Sunnyside Yard, mostly hauling empty passenger stock. They were all out of service and scrapped by the mid 1960s.

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