Pennsylvania Railroad class P5

PRR P5/P5a
PRR P5a #4761
Type and origin Power type Electric Builder PRR Altoona Works (13) Baldwin-Westinghouse (54) General Electric (25)[1] Build date 1931–1935 Total produced 92
Specifications Configuration: ​  • Whyte 4-6-4  • AAR 2-C-2  • UIC 2′Co2′ Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Leading dia. 36 in (914 mm)[2][3][4] Driver dia. 72 in (1,829 mm)[2][3][4] Trailing dia. 36 in (914 mm)[2][3][4] Wheelbase 49 ft 10 in (15.19 m) (total); 20 ft (6.10 m) (rigid)[2][3][4] Length 62 ft (19 m)[2][3][4] Width 10 ft 6 in (3.20 m) (P5, P5a, P5b);[2][3] 10 ft 8.25 in (3.26 m) (P5a (modified))[4] Height 15 ft (4.57 m) over locked-down pantographs[2][3][4] Axle load 74,000 lb (34,000 kg; 34 t) (P5, P5a);[2] 77,800 lb (35,300 kg; 35.3 t) (P5b);[3] 77,000 lb (35,000 kg; 35 t) (P5a (modified))[4] Adhesive weight 220,000 lb (100,000 kg; 100 t) (P5, P5a);[2] 444,700 lb (201,700 kg; 201.7 t) (P5b, all wheels driven);[3] 229,000 lb (104,000 kg; 104 t) (P5a (modified))[4] Loco weight 392,000 lb (178,000 kg; 178 t) (P5, P5a);[2] 444,700 lb (201,700 kg; 201.7 t) (P5b);[3] 394,000 lb (179,000 kg; 179 t) (P5a (modified))[4] Electric system/s 11 kV AC @ 25 Hz Catenary Current pickup(s) Pantograph Traction motors 6× 625 hp (466 kW) AC motors;[2][4] plus 4× 375 hp (280 kW) motors on the trucks on P5b[3] Transmission AC current fed via transformer tap changers to paired motors geared (25:97) to quill drives on each driving axle;[2][4] plus single motors geared to driving axles on end trucks on P5b (gear ratio: 17:50)[3]
Career Operators Pennsylvania Railroad Numbers 4700–4791 Preserved 4700 Disposition One P5 prototype preserved; rest scrapped.

The Pennsylvania Railroad's class P5 comprised 92 mixed-traffic electric locomotives constructed 1931–1935 by the PRR, Westinghouse and General Electric.^[1] Although the original intention was that they work mainly passenger trains, the success of the GG1 locomotives meant that the P5 class were mostly used on freight. A single survivor, prototype #4700, is at the National Museum of Transportation in St Louis, Missouri.

They had an AAR wheel arrangement of 2-C-2, or 2′Co2′ in the UIC classification system — three pairs of driven wheels rigidly mounted to the locomotive, with a two-axle unpowered truck at each end. This is an equivalent to a 4-6-4 in the Whyte notation.^[2][3][4] The PRR did not have any 4-6-4 steam locomotives, so the P5s were the only 4-6-4 type locomotives owned by the PRR.

The first P5s were built with box cabs. A grade crossing accident in which the crew were killed led to the substitution of a central cab to give better crash protection, a streamlined steeple type, in later production, a design which was also applied to the GG1.

When the GG1s were put in passenger service, the P5s were regeared and used in freight service for many years. The last of the class was withdrawn from service in April 1965.^[5]