Baltimore and Ohio class N-1

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B&O #5600 George H. Emerson
Baltimore and Ohio Railroad #5600 George H. Emerson
Type and origin
Power typeSteam
BuilderB&O Mount Clare Shops
Build dateMay 1937
Total produced1
 • Whyte4-4-4-4
 • UIC2′BB2′
Gauge4 ft 8+12 in (1,435 mm) standard gauge
Leading dia.36 in (914 mm)
Driver dia.76 in (1,930 mm)
Trailing dia.42 in (1,067 mm)
Minimum curve13° or 441.68 ft (134.62 m) normal,
18° or 319.62 ft (97.42 m) slow
Length117 ft 0+14 in (35.67 m)
Adhesive weight238,000 lb (108,000 kilograms; 108 metric tons)
Loco weight386,500 lb (175,300 kilograms; 175.3 metric tons)
Tender weight350,000 lb (160,000 kilograms; 160 metric tons)
Total weight736,500 lb (334,100 kilograms; 334.1 metric tons)
Tender typeVanderbilt with two 3-axle trucks
Fuel typeCoal
Fuel capacity46,000 lb (21,000 kilograms; 21 metric tons)
Water cap.22,000 US gal (83,000 L; 18,000 imp gal)
 • Firegrate area
80.5 sq ft (7.48 m2)
Boiler pressure350 lbf/in2 (2.41 MPa)
Heating surface4,897 sq ft (454.9 m2)
 • Tubes and flues4,220 sq ft (392 m2)
 • Firebox677 sq ft (62.9 m2)
 • TypeB&O
 • Heating area1,312 sq ft (121.9 m2)
CylindersFour, duplex
Cylinder size18 in × 26.5 in (457 mm × 673 mm)
Valve gearWalschaerts
Performance figures
Power output3,936 hp (2,935 kW) at cylinders
Tractive effort65,000 lbf (289.1 kN)
Factor of adh.3.66
OperatorsBaltimore and Ohio Railroad
Official nameGeorge H. Emerson
ScrappedOctober 1950

The Baltimore and Ohio Railroad's sole Class N-1 steam locomotive, #5600 (named "George H. Emerson"), was the first duplex locomotive and the first 4-4-4-4 locomotive ever built. It was designed and built by the railroad's own shops in 1937.


The rear set of cylinders were placed beside the firebox. This allowed the locomotive's wheelbase to remain the same. The space beside the firebox was hot and dirty, which caused premature cylinder wear, and the placement of the cylinders limited the size of the firebox. These same problems occurred on the PRR Q1, which also placed the rear cylinders by the firebox. It was built by the B&O's own Mount Clare Shops in 1937; however it had problems with the sizes of the cylinders facing the other direction.


In 1943, No. 5600 was retired from service. The locomotive was then cut up for scrap in 1950.



  • Reed, Brian (June 1972). Pennsylvania Duplexii. Loco Profile 24. Windsor, Berkshire: Profile Publications Limited. pp. 266–267.