Pennsylvania Railroad class T1

Pennsylvania Railroad T1
T1 5549 on display.
Type and origin
Power typeSteam
DesignerRalph P. Johnson[1]
Raymond Loewy[2]
BuilderAltoona Works (5500–5524)
Baldwin Locomotive Works (5525–5549, 6110–6111)
Pennsylvania Railroad T1 Steam Locomotive Trust (5550)[3]
Serial numberAltoona 4560–4584
BLW 72764–72788 (5525–5519)
Build date1942 (6110–6111)
1945–46 (5500–5549)
2014–present (5550)[3]
Total produced52
Specifications
Configuration:
 • Whyte4-4-4-4
 • UIC2′BB2′
Gauge4 ft 8+12 in (1,435 mm)
Leading dia.36 in (914 mm)
Driver dia.80 in (2,032 mm)
Trailing dia.42 in (1,067 mm)
Wheelbase107 ft 0 in (32.61 m)
Length122 ft 9+34 in (37.43 m)
Width11 ft 1 in (3.38 m)
Height6111: 15 ft 6 in (4.72 m)[4]
Axle load71,680 lb (32.51 t)
Adhesive weight279,910 lb (127.0 t)
Loco weight502,200 lb (227.8 t)
Tender weightEmpty: 197,400 lb (89.54 t);
Loaded: 442,500 lb (200.7 t)
Total weight944,700 lb (428.5 t)
Tender type180 P 76 (Prototype), 180 P 84 (Production)
Fuel typeCoal
Fuel capacity85,200 lb (38.65 t)
Water cap.19,200 US gal (73,000 L; 16,000 imp gal)
Firebox:
 • Grate area92 sq ft (8.5 m2)
Boiler100 in (2,540 mm)
Boiler pressure300 lbf/in2 (2.07 MPa)
Heating surface:
 • Firebox490 sq ft (45.5 m2)
 • Tubes and flues4,209 sq ft (391.0 m2)
 • Total surface5,639 sq ft (523.9 m2)
Superheater:
 • TypeType A
 • Heating area1,430 sq ft (132.9 m2)
CylindersFour
Cylinder size19.75 in × 26 in (502 mm × 660 mm), 18.75 in × 26 in (476 mm × 660 mm) (some)
Valve gearFranklin poppet
Valve typePoppet valves
Performance figures
Maximum speed120 mph (193 km/h)
Power output6,500 ihp (4,800 kW)
Tractive effort64,653 lbf (287.6 kN) (85%),[5] 58,271 lbf (259.2 kN) (85%) (some)
Factor of adh.4.33
Career
OperatorsPennsylvania Railroad
ClassT1
Number in class52 original, plus 1 under construction[3]
Numbers6110, 6111, 5500-5549, 5550
LocaleWestern Pennsylvania, Ohio, Indiana, Illinois
First run1942
Retired1953
Withdrawn1952–1953[6]
Scrapped1953–1956[6][3]
DispositionAll 52 original scrapped, 1 new build (PRR 5550) under construction

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.

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]

  1. ^ Staufer 1962, p. 217.
  2. ^ Staufer 1962, p. 225.
  3. ^ a b c d "FAQ Section - The T1 Trust". The Pennsylvania Railroad T1 Steam Locomotive Trust. 2016. Archived from the original on 24 August 2019. Retrieved 23 April 2017.
  4. ^ Reed 1972, p. 271.
  5. ^ Reed 1972, p. 275.
  6. ^ a b Llanso, Steve; Duley, Richard. "Pennsylvania 4-4-4-4, 6-4-4-6, etc. "Duplex Drive" Locomotives of the USA". SteamLocomotive.com. Archived from the original on 27 April 2017. Retrieved 23 April 2017.
  7. ^ "In Defense of the 5500s", Volume 41, Number 1, Pennsylvania Railroad Technical and Historical Society Magazine, Spring, 2008
  8. ^ Kerr, Douglas A. (October 16, 2011). "Spring Equalization for Steam Locomotives" (PDF). Retrieved August 24, 2019.
  9. ^ "Pennsy T1 comeback? Ten questions and answers for the T1 Trust", Volume 75, Number 5, Trains Magazine, May 2015.