In 1923 and 1924 the B&O received seventy-five more 2-10-2s. Fifty were built by Baldwin and the other twenty-five were built by the Lima Locomotive Works. They were all designated as Class S-1. The Baldwin-built locomotives were assigned road numbers 6100 through 6149 and the Lima-built "Santa-Fes" carried road numbers 6150 through 6174.
In 1926, the B&O received fifty more 2-10-2s. This time it received twenty-five from Baldwin and twenty-five from Lima. This group was designated as Class S-1a with the Baldwin-built locomotives getting road numbers 6175 through 6199 and the Lima-built locomotive were assigned road numbers 6200 through 6224.
The Class S-1 and Class S-1a locomotives all had 64" diameter drivers, 30" x 32" cylinders, a 220 psi boiler pressure, they exerted 84,150 pounds of tractive effort and each weighed 436,510 pounds. This group of 125 freight haulers had a heating surface which included 38 sq ft of arch tubes and 67 sq ft of combustion chamber and with 64" diameter drivers they were fast as well as powerful.
There are no surviving B&O 2-10-2 "Santa Fe" type locomotives.
|Class||Qty.||Road Numbers||Year Built||Builder||Notes|
|S||31||6000-6030||1914||Baldwin||Numbers 6009 and 6030 dismantled in 1925 and the boilers used to build two new "Mountain" type locomotives. Fifteen Class S locomotives scrapped in 1938. All the others scrapped between 1953 and 1959.|
|S-1||50||6100-6149||1923-1924||Baldwin||Numbers 6100-6149 scrapped between 1953 and 1959.|
|S-1||25||6150-6174||1923-1924||Lima||Numbers 6150-6174 scrapped between 1953 and 1959.|
|S-1a||25||6175-6199||1926||Lima||Numbers 6175-6199 scrapped between 1953 and 1959.|
|S-1a||25||6200-6224||1926||Baldwin||Numbers 6200-6224 scrapped between 1953 and 1959.|
Firebox heating surface included 65 sq ft (6.04 sq m) of combustion chamber and 35 sq ft (3.25 sq m) from four arch tubes. Originally delivered with Franklin grate shakers, the batch lost that equipment not long after.
First Santa Fes on the B&O, these 31 engines were the archetypal slow-moving weight lifters that operated on heavy grades. The Baldwin specs report maximum grades of 2.4% and maximum curves of 22 degrees (262 foot/79.9 metre radii).
One impressive feature was the 16" (406 mm) piston valves supplied by that ample boiler and grate; their 6 1/4" (159 mm). The later S-1as (Locobase 73) had 6" (152 mm) taller drivers with more effective counterbalancing, a rearranged boiler, and smaller piston valves with longer travel. They offered both greater speed and an impressive ability to haul . In addition, the cylinders were to be arranged for the future application of the Emerson feed water heater and a steam pipe for a booster.
The class was known as the "Big Six," a reference to the road number but probably also borrowing the nickname from the big New York Giants pitcher Christy Mathewson of the same era, whose ability to "put out fires" originally earned him comparison with a well-known New York City fire engine. (Others attribute the nickname to his 6' 1"/1,854 mm stature.)
Big Sixes 6009 and 6030 were bobbed through the deletion of both auxiliary trucks, given new steam-generation components, and served out their careers as mighty Class U 0-10-0 switcher/pusher engines; see Locobase 14986. The boiler design also appeared on the B&O's first Mountains; see Locobase 196.
In 1951, two of the class were tweaked by the shops. 6105, redesignated S-1c, had a new cas engine bed and lightweight pistons, said a later B&O diagram, "by applying engine bed and light weight pistons." The S-1b (6122) added to those changes lightweight rods and crossheads.
The last S-1s retired in 1953. (See Craig Sanders 21 June 2016 post of a essentially perfectly shot Robert Redmond color slide showing Big Six 524 [Lima-built ex-6177) at https://akronrrclub.wordpress.com/tag/bo-steam-locomotives/, last accessed 3 December 2016.)
Lima's works numbers were 6700-6724 in 1924 and 7050-7074 in 1926.
This class of 125 freight haulers came in 1923-1926 from Baldwin (75) and Lima (50). Baldwin's specs for the firebox heating surface area included 42 sq ft (3.9 sq m) in five arch tubes and 85 sq ft (7.9 sq m) of combustion chamber. Later B&O diagrams show 38 sq ft (3.5 sq m) in five arch tubes and 67 sq ft (6.2 sq m) from the combustion chamber. 37 fewer small tubes allowed five more large tubes with superheater elements; the superheater ratio reached superpower levels. A less obvious, but significant, difference was the substitution of 14" (356 mm) piston valves with a maximum 7 1/2" travel for the earlier batch's 16" valves that had 6 1/4" maximum travel.
Baldwin's order includes the notation that the 6100s would be based on Baldwin's tracing 49481 but would use the Duplex stoker, Vanderbilt tender, Commonwealth cast steel tender frames, six-wheel Commonwealth tender trucks while not installing Nicholson thermic syphons. Certain details would be the same as those found in the B&O's Q-4-s 2-8-2s.
Drury (1993) comments that unlike most 2-10-2s, which were low-speed engines "that could pull anything, given enough time," the B&O's were fast as well as powerful. He notes that the larger 64" drivers allowed more effective counterbalancing. Sagle says that the S-1as were rated at 1,600 tons up the notorious Sand Patch Grade unassisted and double that when aided by a helper engine.
Locobase believes Don Ball wrote the best long captions to photographs of any compiler he's encountered. This word picture accompanying a Donahue photo showing two S-1a on the Sand Patch Grade offers strong support for that claim:
"Inside the cab, everything's shaking, the glass dances in the glass at the three-quarter mark, the deck plate slams and bangs, stoker screw grinds, guages jiggle, steam sputters and spits from backhead pipes, the fire roars, and the veteran fireman leans way out to
look at his stack. Steam gauges register a steady 218 pounds. The younger fireman on the road engine does the same, thinkgs looking as though he's overcrowding his fire.
"The lead engine heaves and hunts; rods pound rythmically as the two 'Big Sixes' blast upgrade through Cumberland Narrows, while the crashing echoes of booming stacks hammer hard off the rock. Steadily Second Chicago-97 makes progress along the Pittsburgh Line."
(The class was known as the "Big Six," from the number of the lead engine, but possibly borrowing the nickname from the big New York Giants pitcher Christy Mathewson, whose ability to "put out fires" originally earned him comparison with a well-known New York City fire engine.)
The last S-1a retired in 1959.
|Specifications by Steve Llanso of Sweat House Media|
|Class||S||S-1a, b, c|
|Railroad||Baltimore & Ohio (B&O)||Baltimore & Ohio (B&O)|
|Number in Class||31||125|
|Locomotive Length and Weight|
|Driver Wheelbase (ft)||21||22.30|
|Engine Wheelbase (ft)||40.25||42.90|
|Ratio of driving wheelbase to overall engine wheebase||0.52||0.52|
|Overall Wheelbase (engine & tender) (ft)||76.50||89.90|
|Axle Loading (Maximum Weight per Axle) (lbs)||68,300||69,830|
|Weight on Drivers (lbs)||332,400||347,830|
|Engine Weight (lbs)||410,200||436,810|
|Tender Loaded Weight (lbs)||186,110||298,400|
|Total Engine and Tender Weight (lbs)||596,310||735,210|
|Tender Water Capacity (gals)||9900||15,800|
|Tender Fuel Capacity (oil/coal) (gals/tons)||20||23|
|Minimum weight of rail (calculated) (lb/yd)||111||116|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in)||58||64|
|Boiler Pressure (psi)||205||220|
|High Pressure Cylinders (dia x stroke) (in)||30" x 32"||30" x 32"|
|Tractive Effort (lbs)||86,524||84,150|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||3.84||4.13|
|Firebox Area (sq ft)||358||375|
|Grate Area (sq ft)||88||88|
|Evaporative Heating Surface (sq ft)||5573||5251|
|Superheating Surface (sq ft)||1329||1512|
|Combined Heating Surface (sq ft)||6902||6763|
|Evaporative Heating Surface/Cylinder Volume||212.87||200.57|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||18,040||19,360|
|Same as above plus superheater percentage||21,468||23,619|
|Same as above but substitute firebox area for grate area||87,334||100,650|