USRA 2-10-2 "Santa Fe" Type Locomotives

Class Heavy (Locobase 90)

The more widely emulated of the two USRA "Santa Fe" designs. Alco's Brooks works delivered 135 engines, 95 of them to the Pennsy. Baldwin built 40, including another 30 for the Pennsy. The Frisco liked the engines, according to Eugene Huddleston (Trains, March 1991) while the Pennsy found that when assigned trains in accordance with their tractive power, these engines "handled their tonnage in a satisfactory manner."

The basic design performed adequately, says Huddleston, but the 2-10-2 arrangement had too long a wheelbase on a built-up (as opposed to integrally cast) frame and too little scope for proper counterbalancing. As a result, maintenance costs climbed as frames worked hemselves out of true by flexing and the pounding induced by the long main and side rods. Nevertheless, most other 2-10-2s built after WW I used the same piston, boiler pressure,

and driver diameter dimensions and had similar tractive efforts. Later private designs had more boiler area, a greater percentage of which was superheated.

Class Light (Locobase 89)

One of two basic "Santa Fe" designs standardized near the end of World War I. Alco's Brooks works produced 75 of these, including 50 for the Southern. Baldwin added 19.

The heavy design was more widely produced than this light version, whose small drivers frustrated efforts at counterbalancing masses for smooth riding and whose light weight limited adhesion. See Southern Railway's Ss-1

Specifications
Class	Heavy	Light
Locobase ID	90	89
Railroad	USRA	USRA
Whyte	2-10-2	2-10-2
Road Numbers	10000	10000
Gauge	Std	Std
Builder	Several	Several
Year	1918	1918
Valve Gear	Southern	Southern
	Locomotive Length and Weight
Driver Wheelbase	22.30'	21'
Engine Wheelbase	42.20'	40.30'
Ratio of driving wheelbase to overall engine wheebase	0.53	0.52
Overall Wheelbase (engine & tender)	82.87'	75.97'
Axle Loading (Maximum Weight per Axle)		60000 lbs
Weight on Drivers	293000 lbs	274000 lbs
Engine Weight	380000 lbs	352000 lbs
Tender Light Weight	206100 lbs	188300 lbs
Total Engine and Tender Weight	586100 lbs	540300 lbs
Tender Water Capacity	12000 gals	10000 gals
Tender Fuel Capacity (oil/coal)	16 tons	16 tons
Minimum weight per yard of rail on which locomotive could run	98 lb rail	91 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	63"	57"
Boiler Pressure	190 psi	200 psi
Cylinders (dia x stroke)	30" x 32"	27" x 32"
Tractive Effort	73829 lbs	69575 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	3.97	3.94
	Heating Ability
Firebox Area	429 sq. ft	373 sq. ft
Grate Area	83.20 sq. ft	76.30 sq. ft
Evaporative Heating Surface	5156	4666
Superheating Surface	1230	1085
Combined Heating Surface	6386	5751
Evaporative Heating Surface/Cylinder Volume	196.94	220.03
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	15808	15260
Same as above plus superheater percentage	18970	18312
Same as above but substitute firebox area for grate area	97812	89520
Power L1	13999	14601
Power MT	526.66	587.40