Baltimore & Ohio 2-10-2 "Santa Fe" Locomotives in the USA

The Baltimore & Ohio Railroad took delivery of its first "Santa Fe" type locomotives in 1914. The Baldwin Locomotive works built thirty-one of them for the B&O that year. They were designated as Class S and were assigned road numbers 6000 through 6030. These locomotives had 58" diameter drivers, 30" x 32" cylinders, a 205 psi boiler pressure, they exerted 86,500 pounds of tractive effort and each weighed 410,200 pounds. Number 6000 was delivered with a 190 psi boiler pressure, which resulted in 80,193 pounds of tractive effort and it only weighed 407,060 pounds. The Class S locomotives usually were deployed in slow-moving freight duty on heavy grades. One impressive feature of these locomotives was the 16" piston valves supplied by an ample boiler and grate area.

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, 29.75" x 32" cylinders, a 220 psi boiler pressure, they exerted 82,753 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.


ClassQty.Road NumbersYear BuiltBuilderNotes
S316000-60301914BaldwinNumbers 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-1506100-61491923-1924BaldwinNumbers 6100-6149 scrapped between 1953 and 1959.
S-1256150-61741923-1924LimaNumbers 6150-6174 scrapped between 1953 and 1959.
S-1a256175-61991926LimaNumbers 6175-6199 scrapped between 1953 and 1959.
S-1a256200-62241926BaldwinNumbers 6200-6224 scrapped between 1953 and 1959.

Class Details by Steve Llanso of Sweat House Media

Class S (Locobase 1036)

Data from B&O Staufer Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also Baldwin, DeGolyer, Volume 50, pp. 86-120; and "New and Powerful Type of Locomotive for the Baltimore & Ohio Railroad", Railway and Locomotive Engineering, Volume XXVIII [28], no 8 (August 1914), pp. 279-280 (Thanks to Chris Hohl for his 29 October 2016 email correcting the original tender capacity and weight; and a 17 March email supplying the 6000's original pressure setting and tender information.) Works numbers were 41309 in April 1914; 41631-41632, 41644-41645, 41663 in August; 41681-41683, 41701-41705, 41711-41717 in September; 41757-41761 in October; 41792-41794, 41799-41800 in November.

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.

The design's boiler originally ran at a 200 psi (13.8 sq m) setting; that was soon changed to the 205 psi shown in the specifications. Its tender coal capacity came to 16 tons (14.5 metric tons) and held 10,000 US gallons (37,850 litres) of water

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). R&LE reflected in its assessment the contemporary American focus on steadily increasing tonnage demands. It noted the high tractive effort, which exceeded that of many 2-6-6-2 Mallets, combined with the greater speed capacity and simplicity of construction. These attributes "commend it for heavy road service where operating conditions are severe and engines must be kept in service for a maximum proportion of time. Such conditions are frequently met when business is heavy and there is a shortness of power." Later on, the R&LE report emphasized that a 2-10-2 could generate high tractive effort on more axles than a 2-8-2, thus reducing axle load, concluding that "powerful units can be build for lines having light track construction."

One impressive feature was the 16" (406 mm) piston valves supplied by that ample boiler and grate. 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 cast 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 [], last accessed 3 December 2016.)

Class S-1a, b, c (Locobase 73)

Data from 1930 Locomotive Cyclopedia tables, DeGolyer, Volume 74, pp. 37+, and from 1954 B & O locomotive diagram assortment supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also Don Ball, Jr, Decade of the Trains -- the 1940s (Boston, MA: New York Graphic Society, 1977), p. 59. (Thanks to Chris Hohl for his 24 January 2017 email noting the specification's 29 3/4" cylinder diameter and for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error .)

Baldwin works numbers were 57214-57216, 57232, 57330-57338 in October 1923; 57439-57440, 57447-57471 in November; 57569-57576 in December; 57594-57595 in January 1924; 59062-59064 in March 1926; 59114-59121 in April; 59178-59186, 59228-59232 in May.

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.

Supplemental note 253 tells us the story behind the odd cylinder dimension reported by Chris Hohl. The spec advises that the cylinder would be similar to the earlier Baldwin S class SantaFes, "modified for the double rail of frame, similar to railroad's Q-4-b loco[motive]s." These were Mikados (Locobase 941) that likewise used cylinders whose actual diameter was a 1/4" less than the nominal figure, which was 26" (660 mm).

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.

Principal Dimensions by Steve Llanso of Middle Run Media

ClassSS-1a, b, c
Locobase ID1036 73
RailroadBaltimore & Ohio (B&O)Baltimore & Ohio (B&O)
Number in Class31125
Road Numbers6000-60306100-6224
Number Built31125
Valve GearWalschaertBaker
Locomotive Length and Weight
Driver Wheelbase (ft / m)21 / 6.4022.30 / 6.80
Engine Wheelbase (ft / m)40.25 / 12.2742.90 / 13.08
Ratio of driving wheelbase to overall engine wheelbase 0.52 0.52
Overall Wheelbase (engine & tender) (ft / m)76.50 / 23.3289.90 / 27.40
Axle Loading (Maximum Weight per Axle) (lbs / kg)68,300 / 30,98069,830 / 31,674
Weight on Drivers (lbs / kg)332,400 / 150,774347,830 / 157,773
Engine Weight (lbs / kg)410,200 / 186,064436,810 / 198,134
Tender Loaded Weight (lbs / kg)186,110 / 84,418298,400 / 135,352
Total Engine and Tender Weight (lbs / kg)596,310 / 270,482735,210 / 333,486
Tender Water Capacity (gals / ML)9900 / 37.5015,800 / 59.85
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)20 / 1823 / 21
Minimum weight of rail (calculated) (lb/yd / kg/m)111 / 55.50116 / 58
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)58 / 147364 / 1626
Boiler Pressure (psi / kPa)205 / 14.10220 / 15.20
High Pressure Cylinders (dia x stroke) (in / mm)30" x 32" / 762x81329.75" x 32" / 756x813
Tractive Effort (lbs / kg)86,524 / 39246.6782,753 / 37536.17
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.84 4.20
Heating Ability
Tubes (number - dia) (in / mm)269 - 2.25" / 57232 - 2.25" / 57
Flues (number - dia) (in / mm)48 - 5.5" / 14053 - 5.5" / 140
Flue/Tube length (ft / m)23 / 7.0123 / 7.01
Firebox Area (sq ft / m2)358 / 33.26375 / 34.84
Grate Area (sq ft / m2)88 / 8.1888 / 8.18
Evaporative Heating Surface (sq ft / m2)5573 / 517.745251 / 488.01
Superheating Surface (sq ft / m2)1329 / 123.471512 / 140.52
Combined Heating Surface (sq ft / m2)6902 / 641.216763 / 628.53
Evaporative Heating Surface/Cylinder Volume212.87203.92
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation18,04019,360
Same as above plus superheater percentage21,46823,619
Same as above but substitute firebox area for grate area87,334100,650
Power L114,62718,895
Power MT485.06598.80

All material Copyright ©
Wes Barris