Pennsylvania Railroad class T1

Specifications
Specifications
Configuration:;
• Whyte	4-4-4-4
• UIC	2′BB2′
Gauge	4 ft 8+1⁄2 in (1,435 mm)
Leading dia.	36 in (914 mm)
Driver dia.	80 in (2,032 mm)
Trailing dia.	42 in (1,067 mm)
Wheelbase	107 ft 0 in (32.61 m)
Length	122 ft 9+3⁄4 in (37.43 m)
Width	11 ft 1 in (3.38 m)
Height	6111: 15 ft 6 in (4.72 m)
Axle load	71,680 lb (32.51 t)
Adhesive weight	279,910 lb (127.0 t)
Loco weight	502,200 lb (227.8 t)
Tender weight	Empty: 197,400 lb (89.54 t);; Loaded: 442,500 lb (200.7 t)
Total weight	944,700 lb (428.5 t)
Tender type	180 P 84
Fuel type	Coal
Fuel capacity	85,200 lb (38.65 t)
Water cap.	19,200 US gal (73,000 L; 16,000 imp gal)
Firebox:
• Grate area	92 sq ft (8.5 m2)
Boiler	100 in (2,540 mm)
Boiler pressure	300 lbf/in2 (2.07 MPa)
Heating surface	5,639 sq ft (523.9 m2)
• Tubes and flues	4,209 sq ft (391.0 m2)
• Firebox	490 sq ft (45.5 m2)
Superheater:;
• Type	Type A
• Heating area	1,430 sq ft (132.9 m2)
Cylinders	Four
Cylinder size	19.75 in × 26 in (502 mm × 660 mm)
Valve gear	Franklin poppet
Valve type	Poppet valves

Type and origin
Type and origin
Power type	Steam
Designer	Ralph P. Johnson; Raymond Loewy
Builder	Altoona Works (5500–5524); Baldwin Locomotive Works (5525–5549, 6110–6111); Pennsylvania Railroad T1 Steam Locomotive Trust (5550)
Serial number	Altoona 4560–4584; BLW 72764–72788 (5525–5519)
Build date	1942 (6110–6111); 1945–46 (5500–5549); 2014–present (5550)
Total produced	52

Pennsylvania Railroad T1
Pennsylvania Railroad T1
	T1 prototype 6110 at the Baldwin plant ready for delivery to the PRR
Power type
Type and origin
Power type	Steam
Designer	Ralph P. Johnson; Raymond Loewy
Builder	Altoona Works (5500–5524); Baldwin Locomotive Works (5525–5549, 6110–6111); Pennsylvania Railroad T1 Steam Locomotive Trust (5550)
Serial number	Altoona 4560–4584; BLW 72764–72788 (5525–5519)
Build date	1942 (6110–6111); 1945–46 (5500–5549); 2014–present (5550)
Total produced	52
Configuration:;
Specifications
Configuration:;
• Whyte	4-4-4-4
• UIC	2′BB2′
Gauge	4 ft 8+1⁄2 in (1,435 mm)
Leading dia.	36 in (914 mm)
Driver dia.	80 in (2,032 mm)
Trailing dia.	42 in (1,067 mm)
Wheelbase	107 ft 0 in (32.61 m)
Length	122 ft 9+3⁄4 in (37.43 m)
Width	11 ft 1 in (3.38 m)
Height	6111: 15 ft 6 in (4.72 m)
Axle load	71,680 lb (32.51 t)
Adhesive weight	279,910 lb (127.0 t)
Loco weight	502,200 lb (227.8 t)
Tender weight	Empty: 197,400 lb (89.54 t);; Loaded: 442,500 lb (200.7 t)
Total weight	944,700 lb (428.5 t)
Tender type	180 P 84
Fuel type	Coal
Fuel capacity	85,200 lb (38.65 t)
Water cap.	19,200 US gal (73,000 L; 16,000 imp gal)
Firebox:
• Grate area	92 sq ft (8.5 m2)
Boiler	100 in (2,540 mm)
Boiler pressure	300 lbf/in2 (2.07 MPa)
Heating surface	5,639 sq ft (523.9 m2)
• Tubes and flues	4,209 sq ft (391.0 m2)
• Firebox	490 sq ft (45.5 m2)
Superheater:;
• Type	Type A
• Heating area	1,430 sq ft (132.9 m2)
Cylinders	Four
Cylinder size	19.75 in × 26 in (502 mm × 660 mm)
Valve gear	Franklin poppet
Valve type	Poppet valves
Maximum speed
Performance figures
Maximum speed	over 140 mph (255 km/h)
Power output	6,500 ihp (4,800 kW)
Tractive effort	64,653 lbf (287.6 kN) (85%)
Factor of adh.	4.33
Operators
Career
Operators	Pennsylvania Railroad
Class	T1
Number in class	52 original, plus 1 under construction
Numbers	6110, 6111, 5500-5549, 5550
Locale	Western Pennsylvania, Ohio, Indiana, Illinois
First run	1942
Retired	1953
Withdrawn	1952–1953
Scrapped	1953–1956
Disposition	All 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. 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. 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. 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.

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