The reference for locomotives and railcars


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Boston & Maine class R-1
United States | 1935 | 18 produced
No. 4117 "Hercules"
No. 4117 "Hercules"
flickr/Mike Robbins

The class R-1 Mountains were the last steam locomotives ordered by the Boston & Maine. They were among the heaviest Mountains and were built in four batches between 1935 and 1941. Initially five R-1a were built, in 1937 another five R-1b, in 1939 three R-1c and finally five R-1d. All locomotives were given names that were determined in a competition.

From the R-1b onwards, the spoke wheels on the driven axle were replaced with disc wheels. The R-1c was almost identical to the R-1b, only the R-1d underwent major changes. It now had disc wheels on all drivers and the Coffin feed water heater was replaced with a Worthington one. In addition, there was now a seven-axle tender instead of the six-axle one. Thirteen R-1s were sold to the B&O in 1947, the remaining five were scrapped in 1955 and 1956.

Axle config4-8-2 (Mountain) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase44 ft 2 in
Fixed wheelbase19 ft 3 in
Service weight416,100 lbs
Adhesive weight269,400 lbs
Total weight788,800 lbs
Axle load68,900 lbs
Water capacity20,200 us gal
Fuel capacity45,000 lbs (coal)
Power sourcesteam
Estimated power4,500 hp (3,356 kW)
Optimal speed42 mph
Starting effort67,918 lbf
Power Plant
Driver diameter73 in
Boiler pressure240 psi
Expansion typesimple
Cylinderstwo, 28 x 31 in
Grate area79 sq ft
Firebox area475 sq ft
Tube heating area4,036 sq ft
Evaporative heating area4,511 sq ft
Superheater area1,924 sq ft
Total heating area6,435 sq ft
Calculated Values
steam locomotive
last changed: 04/2024

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