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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.

VariantT-1aT-1b
General
Built19281929
ManufacturerLima
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
Power sourcesteam
Estimated power4,100 hp (3,057 kW)4,700 hp (3,505 kW)
Optimal speed39 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
Boiler
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
freight
booster
last changed: 05/2022
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