The reference for locomotives and railcars


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Steam Locomotives of the Boston & Maine (B&M)[Inhalt]
Boston & Maine classes K-5a and K-5b
United States | 1901 | 34 produced
Railway and Locomotive Engineering, January 1901

Parallel to the K-6 with a two-cylinder compound engine, the Boston & Maine had ALCO in Schenectady build 34 class K-5a and b locomotives with a simple engine. They still had the Stephenson controls but piston valves. According to “Railway and Locomotive Engineering”, the dimensions of the heating surfaces were very well matched to the size of the cylinders. The locomotives later designated as K-5d were actually K-7s with superheaters

Axle config2-8-0 (Consolidation) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase25 ft 6 in
Fixed wheelbase17 ft
Total wheelbase53 ft 10 ft
Service weight162,000 lbs
Adhesive weight142,000 lbs
Axle load35,500 lbs
Water capacity5,000 us gal
Fuel capacity20,000 lbs (coal)
Power sourcesteam
Estimated power1,500 hp (1,119 kW)
Optimal speed29 mph
Starting effort33,443 lbf
Power Plant
Driver diameter61 in
Boiler pressure200 psi
Expansion typesimple
Cylinderstwo, 20 x 30 in
Grate area46.5 sq ft
Firebox area157 sq ft
Tube heating area2,718 sq ft
Evaporative heating area2,875 sq ft
Total heating area2,875 sq ft
Calculated Values
steam locomotive
last changed: 03/2023
Boston & Maine class T-1
United States | 1928 | 25 produced
T-1a Nr. 4008 im April 1939 in Billerica, Massachusetts
T-1a Nr. 4008 im April 1939 in Billerica, Massachusetts
Edward R. Batson, Jr. / Boston & Mayne Historical Society archivees

In 1928, the Boston & Maine initially procured 20 Berkshire-type locomotives near Lima. This meant a leading axle, four coupled axles and a two-axle bogie under the firebox. Thanks to the bogie, a grate area of exactly 100 square feet was possible. After the 20 engines of the T-1a class, another five were procured in the following year as the T-1b class. These were slightly heavier than the T-1a, which were later upgraded to the same level.

Because the adhesive weight was relatively low compared to the engine, the maximum cutoff was set at 60 percent. The actually achieved starting tractive force therefore deviates from the result of the formula usually used, as this assumes a cutoff of 85 percent. An additional 12,000 pounds of traction came from a booster driving the rear axle of the bogie. A special feature of the locomotives was the Coffin feedwater heater, which lay in a semicircle above the smokebox.

The locomotives were unpopular in operation, as the bogie was always the cause of problems. Because the weight of the firebox rested on it, high forces acted on the boiler when running through curves. In addition, the bogie tended to derail when reversing.

T-1a No. 4012 in August 1940 at North Pownal, Vermont with clearly visible coffin-type feedwater heater on the smoke box
T-1a No. 4012 in August 1940 at North Pownal, Vermont with clearly visible coffin-type feedwater heater on the smoke box
John P. Ahrens / collection Taylor Rush

In view of the problems, the Boston & Maine was able to sell ten engines to the Southern Pacific and seven to the Santa Fe during World War II. The Santa Fé gave the locomotives a rebuild that increased boiler pressure to 270 psi and used smaller diameter, longer stroke cylinders. These were able to prove themselves in service until 1954, while the others had already disappeared in 1949.

Axle config2-8-4 (Berkshire) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase41 ft 8 1/2 in
Fixed wheelbase16 ft 6 in
Service weight393,000 lbs406,900 lbs
Adhesive weight250,200 lbs261,800 lbs
Total weight609,400 lbs735,500 lbs
Axle load63,000 lbs65,900 lbs
Water capacity12,000 us gal17,500 us gal
Fuel capacity36,000 lbs (coal)46,000 lbs (coal)
Power sourcesteam
Estimated power4,400 hp (3,281 kW)4,700 hp (3,505 kW)
Optimal speed42 mph39 mph
Starting effort66,640 lbf76,160 lbf
Booster12,000 lbf
Power Plant
Driver diameter63 in
Boiler pressure210 psi240 psi
Expansion typesimple
Cylinderstwo, 28 x 30 in
Grate area100 sq ft
Firebox area405 sq ft
Tube heating area4,728 sq ft
Evaporative heating area5,133 sq ft
Superheater area2,136 sq ft
Total heating area7,269 sq ft
Calculated Values
steam locomotive
last changed: 05/2022
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
Boston & Maine class P-4
United States | 1934 | 10 produced
P-4a No. 3710 “Peter Cooper”
P-4a No. 3710 “Peter Cooper”
collection Richard Driver

The last ten Pacifics that the Boston & Maine purchased were also the last Pacifics that Lima manufactured. Their task was regional traffic over distances of up to around 200 miles, and they were designed for an average speed of 70 mph or 113 km/h. The firebox contained three thermic syphons and arch tubes. The coffin feed water heater was concealed in the smokebox. Initially there was a skyline casing on the top of the boiler, which was later removed. The locomotives from the two production years 1934 and 1937 were designated P-4a and P-4b. They were given names that were chosen in a competition among kindergarten children and students. Only 3713, which is currently being overhauled in Steamtown, has been preserved.

Built1934, 1937
Axle config4-6-2 (Pacific) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase36 ft 11 in
Fixed wheelbase14 ft
Total wheelbase77 ft 7 in
Service weight339,200 lbs
Adhesive weight209,500 lbs
Total weight580,000 lbs
Axle load68,900 lbs
Water capacity12,000 us gal
Fuel capacity37,000 lbs (coal)
Power sourcesteam
Estimated power3,600 hp (2,685 kW)
Optimal speed56 mph
Starting effort40,918 lbf
Power Plant
Driver diameter80 in
Boiler pressure260 psi
Expansion typesimple
Cylinderstwo, 23 x 28 in
Grate area66.9 sq ft
Firebox area320 sq ft
Tube heating area3,528 sq ft
Evaporative heating area3,848 sq ft
Superheater area966 sq ft
Total heating area4,814 sq ft
Calculated Values
steam locomotive
last changed: 01/2023

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