In 1923, ALCO delivered another ten 2-10-2s which were designated as Class S-1b with road numbers 3020 through 3029 assigned. They had 61" diameter drivers, 29" x 32" cylinders, a 190 psi boiler pressure, they exerted 71,251 pounds of tractive effort and each weighed 372,100 pounds.
During WWII the B&M rebuilt four of the Class S-1a (numbers 2900, 2901, 2902 and 2930) locomotives to have lighter axle loads which resulted in a total locomotive weight of 369,200 pounds.
|Class||Qty.||Road Numbers||Year Built||Builder||Notes|
|S-1a||20||3000-3019||1920||ALCO||Six of Class S-1a locomotives sold to the Maine Central between 1936 and 1947 and became six of MEC numbers 651-658. All the others scrapped between 1946 and 1949.|
|S-1b||10||3020-3029||1923||ALCO||Numbers 3020 and 3029 sold to the Maine Central and became two of MEC numbers 651-658. Numbers 3021-3028 scrapped between 1940 and 1948.|
Drury (1993) describes these as "fat and ponderous." The Locomotive Cyclopedia explains that the B&M "needed a powerful locomotive to handle its east and west business over grades of 0.76% eastbound and 1% westbound." Soon after its introduction, the 1922 guide reported that the design "has met the requirements fully, handling trains of 2,850 tons--adjusted--eastbound, and 1,950 tons--adjusted--westbound, the latter trains having the bulk of empties."
Ten of the S-1a were rebuilt into S-1c beginning in April 1940, which was a relatively minor effort-- some were fitted with Elesco or Worthington feedwater heaters and others refitted with a copper firebox of identical dimensions to the original. They did shed some weight, however, compared to the oafish S-1as.
Eight of the class were sold to the Maine Central as Class A beginning with the 3000 in December 1936 and 3008 and 3017 in January 1937. 3009 followed in August 1940, 3020 and 3029 in September 1944, 3005 in April 1946, and 3014 completed the sextet in March 1947. MC road numbers were 651-658.
S-1-b 3028 must have been damaged, as it arrived at the scrapyard in February 1940. All of the B&Ms were scrapped between August 1946 and December 1949. All but two of the Maine Central engines were scrapped in the late 1940s; 856 went in December 1950 and, for some reason, 855 held on until June 1953.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Railroad||Boston & Maine (B&M)|
|Number in Class||30|
|Road Numbers||3000-3029/2900-2909 (as S-1c)|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||21.83 / 6.65|
|Engine Wheelbase (ft / m)||39.58 / 12.06|
|Ratio of driving wheelbase to overall engine wheebase||0.55|
|Overall Wheelbase (engine & tender) (ft / m)||79.50 / 24.23|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||68,100 / 30,890|
|Weight on Drivers (lbs / kg)||320,400 / 145,331|
|Engine Weight (lbs / kg)||377,800 / 171,367|
|Tender Loaded Weight (lbs / kg)||206,000 / 93,440|
|Total Engine and Tender Weight (lbs / kg)||583,800 / 264,807|
|Tender Water Capacity (gals / ML)||12,000 / 45.45|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||16 / 14.50|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||107 / 53.50|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||61 / 1549|
|Boiler Pressure (psi / kPa)||190 / 13.10|
|High Pressure Cylinders (dia x stroke) (in / mm)||29" x 32" / 737x813|
|Tractive Effort (lbs / kg)||71,251 / 32318.95|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.50|
|Firebox Area (sq ft / m2)||364 / 33.83|
|Grate Area (sq ft / m2)||80.30 / 7.46|
|Evaporative Heating Surface (sq ft / m2)||4646 / 431.78|
|Superheating Surface (sq ft / m2)||1145 / 106.41|
|Combined Heating Surface (sq ft / m2)||5791 / 538.19|
|Evaporative Heating Surface/Cylinder Volume||189.91|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||15,257|
|Same as above plus superheater percentage||18,308|
|Same as above but substitute firebox area for grate area||82,992|