The Pennsylvania Railroad (PRR) class T1 duplex-drive 4-4-4-4 steam locomotives, introduced in 1942 with two prototypes and later in 1945-1946 with 50 production examples, were the last steam locomotives built for the PRR and arguably its most controversial. They were ambitious, technologically sophisticated, powerful, fast and distinctively streamlined by Raymond Loewy. However, they were also prone to wheelslip both when starting and at speed, in addition to being complicated to maintain and expensive to run. [citation needed] The PRR decided in 1948 to place diesel locomotives on all express passenger trains, leaving unanswered questions as to whether the T1's flaws were solvable, especially taking into account that the two prototypes did not have the problems inherent to the production units.
Quick Facts Type and origin, Power type ...
Pennsylvania Railroad T1 |
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T1 5549 on display. |
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Specifications |
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Configuration:
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• Whyte | 4-4-4-4 |
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• UIC | 2′BB2′ |
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Gauge | 4 ft 8+1⁄2 in (1,435 mm) |
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Leading dia. | 36 in (914 mm) |
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Driver dia. | 80 in (2,032 mm) |
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Trailing dia. | 42 in (1,067 mm) |
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Wheelbase | 107 ft 0 in (32.61 m) |
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Length | 122 ft 9+3⁄4 in (37.43 m) |
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Width | 11 ft 1 in (3.38 m) |
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Height | 6111: 15 ft 6 in (4.72 m) |
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Axle load | 71,680 lb (32.51 t) |
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Adhesive weight | 279,910 lb (127.0 t) |
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Loco weight | 502,200 lb (227.8 t) |
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Tender weight | Empty: 197,400 lb (89.54 t); Loaded: 442,500 lb (200.7 t) |
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Total weight | 944,700 lb (428.5 t) |
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Tender type | 180 P 84 |
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Fuel type | Coal |
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Fuel capacity | 85,200 lb (38.65 t) |
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Water cap. | 19,200 US gal (73,000 L; 16,000 imp gal) |
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Firebox: | |
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• Grate area | 92 sq ft (8.5 m2) |
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Boiler | 100 in (2,540 mm) |
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Boiler pressure | 300 lbf/in2 (2.07 MPa) |
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Heating surface: | |
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• Firebox | 490 sq ft (45.5 m2) |
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• Tubes and flues | 4,209 sq ft (391.0 m2) |
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• Total surface | 5,639 sq ft (523.9 m2) |
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Superheater:
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• Type | Type A |
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• Heating area | 1,430 sq ft (132.9 m2) |
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Cylinders | Four |
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Cylinder size | 19.75 in × 26 in (502 mm × 660 mm) |
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Valve gear | Franklin poppet |
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Valve type | Poppet valves |
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Performance figures |
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Maximum speed | over 140 mph (255 km/h) |
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Power output | 6,500 ihp (4,800 kW) |
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Tractive effort | 64,653 lbf (287.6 kN) (85%) |
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Factor of adh. | 4.33 |
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Career |
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Operators | Pennsylvania Railroad |
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Class | T1 |
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Number in class | 52 original, plus 1 under construction[3] |
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Numbers | 6110, 6111, 5500-5549, 5550 |
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Locale | Western Pennsylvania, Ohio, Indiana, Illinois |
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First run | 1942 |
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Retired | 1953 |
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Withdrawn | 1952–1953[6] |
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Scrapped | 1953–1956[6][3] |
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Disposition | All 52 original scrapped, 1 new build (PRR 5550) under construction |
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Close
An article appearing in a 2008 issue of the Pennsylvania Railroad Technical and Historical Society Magazine showed that inadequate training for engineers transitioning to the T1 may have led to excessive throttle applications, resulting in driver slippage.[7] Another root cause of wheelslip was faulty "spring equalization": The stiffnesses of the springs supporting the locomotive over the axles were not adjusted to properly equalize the wheel-to-track forces.[8] The drivers were equalized together but not equalized with the engine truck. In the production fleet the PRR equalized the engine truck with the front engine and the trailing truck with the rear engine, which helped to solve the wheelslip problem.[9]