PRR T1

Pennsylvania Railroad T1

A T1 at the Baldwin plant ready for delivery to the PRR

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

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) Length 122 ft 9 3⁄4 in (37.43 m) Width 11 ft 1 in (3.38 m) Height 6111: 16 ft 6 in (5.03 m) Axle load 71,680 lb (32,510 kg; 32.51 t) Adhesive weight 279,910 lb (127,000 kg; 127.0 t) Loco weight 502,200 lb (227,800 kg; 227.8 t) Tender weight Empty: 197,400 lb (89,540 kg; 89.54 t); Loaded: 442,500 lb (200,700 kg; 200.7 t) Tender type 180 P 84 Fuel type Coal Fuel capacity 85,200 lb (38,650 kg; 38.65 t) Water cap 19,200 US gal (73,000 l; 16,000 imp gal) Boiler pressure 300 lbf/in2 (2.07 MPa) Heating surface 5,639 sq ft (523.9 m2)  • Firebox 490 sq ft (45.5 m2) Superheater: ​  • Heating area 1,430 sq ft (132.9 m2) Cylinders Four Cylinder size 19.75 in × 26 in (502 mm × 660 mm) Valve type Poppet valves

Performance figures Tractive effort 64,650 lbf (287.6 kN) (85%)

Career Operators Pennsylvania Railroad Class T1 Number in class 52 original, plus 1 under construction Numbers 6110, 6111, 5500-5549, 5550 Withdrawn 1952–1953 Scrapped 1953–1956 Disposition Original 52 scrapped, 1 under construction

The Pennsylvania Railroad's 52 T1 class duplex-drive 4-4-4-4 steam locomotives, introduced in 1942 (2 prototypes) and 1945-1946 (50 production), were their last steam locomotives built and their 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, complicated to maintain, and expensive to run. The PRR vowed in 1948 to place diesel locomotives on all express passenger trains, leaving unanswered questions of whether the T1's flaws were solvable. An article in the Pennsylvania Railroad Technical and Historical Society Magazine published in 2008 revealed that the wheel-slip problems may have been caused by the failure to properly educate engineers transitioning to the T1, resulting in excessive throttle applications, which in turn caused the driving wheels to slip. Another root cause of wheel slip was faulty spring equalization. The drivers were equalized together and 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 wheel-slip problem.

Before the T1, the last production express passenger engine the PRR had produced was the K4s of 1914, produced until 1928. Two experimental enlarged K5 locomotives were produced in 1929, but they were not considered enough of an improvement to be worthwhile. After that the PRR's attention switched to electrification and the production of electric locomotives; apparently the railroad had no need for more steam locomotives.

But the deficiencies of the K4s became more obvious during the 1930s. They were fine locomotives, but as train lengths increased they proved too small; double headed K4s locomotives became the norm on many trains. The railroad had locomotives to spare, but paying two crews on two locomotives per train was expensive. Meanwhile, other railroads were leaping ahead, developing larger passenger power. Rival New York Central built 4-6-4 Hudsons, while other roads developed passenger 4-8-2 "Mountain" types and then 4-8-4 "Northern" designs. The PRR's steam power began to look outdated.