Union Pacific 2-10-2 "Santa Fe" Type Locomotives

Class TTT-1/2 (Locobase 87)

Data from table in 1930 Locomotive Cyclopedia.

These were the first of 174 TTT (Two-Ten-Two) that had similar cylinder and driver dimensions. 90 went to the parent road (Baldwin 43, Lima 37, Brooks 10), 19 (Baldwin 11, Brooks 8) to Oregon Short Line (OSL), 15 to Oregon-Washington Railroad & Navigation (OWR&N), and 55 (all Baldwin) to the Los Angeles & Salt Lake City (LA&SL).

This first group had 32 sq ft of arch tubes contributing to the firebox heating surface. About half were fitted with Elesco feedwater heaters. The other half had Coffin type which added about 700 lb to the adhesion weight.

Retirements began in 1948 and took most of a decade to complete.

Class TTT-4 (Locobase 6590)

Data from UP 1938 to 1958 Locomotive and Tender Diagrams- Part II (Greater than 70 FT) supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 53403-53404, 53435-53436, 53465-53466 in July 1920; 53506-53507, 53527-53528, 53558-53559, 53616 in August; 53617, 53647-53648, 53675-53677, 53705-53706, 53746 in September; 53844, 53909 in October; 53943 in November.

Delivered after the first World War, these were duplicates of the first batch (Locobase 87).

Class TTT-6 (Locobase 6591)

Data from 1938 to 1958 Union Pacific Locomotive and Tender Diagrams- Part II (Greater than 70 FT) supplied in May 2005 by Allen Stanley from his extensive collection.

Continuing in the same design as the earlier TTTs, this larger group was supplied by three builders. Alco-Brooks (10) 5040-5049, Baldwin (3) 5050-5052 (works numbers were 56714-56716 in July 1923), and Lima (32) 5053-5084. One set of 5 additional locomotives were fitted with Nicholson thermic syphons; see Locobase 6592.

Class TTT-6 (Locobase 6592)

Data from 1938 to 1958 Union Pacific Locomotive and Tender Diagrams- Part II (Greater than 70 FT) supplied in May 2005 by Allen Stanley from his extensive collection.

This interesting quintet shared every characteristic with the previous 84 locomotives in the TTT wheel arrangement save one: the firebox was completely changed. Grate area stayed the same, but in place of 32 sq ft of arch tubes, the new firebox had 118 sq ft of Nicholson thermic syphons. The change increased the direct heating surface by 20%.By the numbers, at least, these were considerably more powerful locomotives.

Specifications
Class	TTT-1/2	TTT-4	TTT-6	TTT-6
Locobase ID	87	6590	6591	6592
Railroad	Union Pacific (UP)	Union Pacific (UP)	Union Pacific (UP)	Union Pacific (UP)
Whyte	2-10-2	2-10-2	2-10-2	2-10-2
Road Numbers	5000-5014	5015-5039	5040-5084	5085-86
Gauge	Std	Std	Std	Std
Builder	Baldwin	Baldwin	several	Lima
Year	1917	1920	1923	1923
Valve Gear	Walschaert	Walschaert	Walschaert	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	22.50'	22.50'	22.50'	22.50'
Engine Wheelbase	41.42'	41.42'	41.42'	41.42'
Ratio of driving wheelbase to overall engine wheebase	0.54	0.54	0.54	0.54
Overall Wheelbase (engine & tender)		80.35'	80.35'	80.35'
Axle Loading (Maximum Weight per Axle)	58000 lbs		59500 lbs	59500 lbs
Weight on Drivers	288700 lbs	286460 lbs	297500 lbs	297500 lbs
Engine Weight	362200 lbs	382100 lbs	383900 lbs	383900 lbs
Tender Light Weight	287000 lbs	218100 lbs	218100 lbs	218100 lbs
Total Engine and Tender Weight	649200 lbs	600200 lbs	602000 lbs	602000 lbs
Tender Water Capacity	15000 gals	12000 gals	12000 gals	12000 gals
Tender Fuel Capacity (oil/coal)	21 tons	20 tons	20 tons	20 tons
Minimum weight per yard of rail on which locomotive could run	96 lb rail	95 lb rail	99 lb rail	99 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	63"	63"	63"	63"
Boiler Pressure	200 psi	200 psi	200 psi	200 psi
Cylinders (dia x stroke)	29.5" x 30"	29.5" x 30"	29.5" x 30"	29.5" x 30"
Tractive Effort	70449 lbs	70449 lbs	70449 lbs	70449 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.10	4.07	4.22	4.22
	Heating Ability
Firebox Area	368 sq. ft	368 sq. ft	368 sq. ft	444 sq. ft
Grate Area	84 sq. ft	84 sq. ft	84 sq. ft	84 sq. ft
Evaporative Heating Surface	5117	5117	5117	5203
Superheating Surface	1165	1165	1165	1165
Combined Heating Surface	6282	6282	6282	6368
Evaporative Heating Surface/Cylinder Volume	215.61	215.61	215.61	219.24
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	16800	16800	16800	16800
Same as above plus superheater percentage	19992	19992	19992	20160
Same as above but substitute firebox area for grate area	87584	87584	87584	106560
Power L1	15434	15434	15434	15846
Power MT	589.30	593.91	571.87	587.13