The reference for locomotives and railcars


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Baltimore & Ohio class P-7
United States | 1927 | 20 produced
Baltimore & Ohio
No. 5303 “President Madison” without streamlined fairing
No. 5303 “President Madison” without streamlined fairing
Howard Locomotive Photographs
No. 5301 “President Adams” with streamlined fairing
No. 5301 “President Adams” with streamlined fairing
collection Taylor Rush

In 1927, the B&O put a total of 20 examples of the P-7 class into service, which at the time were the most powerful Pacifics ever. The power was achieved with a coupling wheel diameter of 80 inches and cylinders measuring 27 by 28 inches. The firebox, with a combustion chamber and thermosiphons, came in at 394 square feet. The first locomotive was manufactured with a booster on the trailing axle, the others were only prepared for its later installation. They were given names after the first 20 Presidents of the United States, beginning with No. 5300 “President Washington”.

The P-7 pulled the most important express trains of the B&O. Over time, there was no uniform modernization of the class, but various conversions. This resulted in the classes P-7a to P-7d, which differed primarily in the heating area and, among other things, had different superheaters. The P-7a and P-7d also featured a streamlined fairing. They pulled important trains such as the “Royal Blue” and the “Cincinnatian”. Their service ended in 1958 after the introduction of diesel locomotives in express service.

VariantP-7P-7arebuilt P-7b, cP-7d
ManufacturerBaldwinBaltimore & Ohio
Axle config4-6-2 (Pacific) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase37 ft 1 in
Fixed wheelbase14 ft
Service weight326,000 lbs340,000 lbs332,000 lbs347,500 lbs
Adhesive weight201,000 lbs207,000 lbs204,000 lbs211,000 lbs
Total weight544,000 lbs579,500 lbs550,000 lbs713,500 lbs
Axle load68,000 lbs70,000 lbs69,000 lbs71,000 lbs
Water capacity11,000 us gal13,000 us gal11,000 us gal20,000 us gal
Fuel capacity34,000 lbs (coal)39,000 lbs (coal)34,000 lbs (coal)56,000 lbs (coal)
Power sourcesteam
Estimated power3,750 hp (2,796 kW)3,800 hp (2,834 kW)3,650 hp (2,722 kW)3,800 hp (2,834 kW)
Optimal speed48 mph49 mph47 mph49 mph
Top speed85 mph
Starting effort49,882 lbf
Power Plant
Driver diameter80 in
Boiler pressure230 psi
Expansion typesimple
Cylinderstwo, 27 x 28 in
Grate area70.3 sq ft
Firebox area394 sq ft429 sq ft379 sq ft429 sq ft
Tube heating area3,452 sq ft3,448 sq ft3,264 sq ft3,414 sq ft
Evaporative heating area3,846 sq ft3,877 sq ft3,643 sq ft3,843 sq ft
Superheater area932 sq ft908 sq ft950 sq ft
Total heating area4,778 sq ft4,809 sq ft4,551 sq ft4,793 sq ft
Calculated Values
steam locomotive
last changed: 06/2022

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