Union Pacific Steam Locomotives

This page was last updated on April 20, 2010.

Wheel Arrangements

(Based on an original completed in April 1996; updated in August 1998; with additional updates starting in March 2009)

Steam locomotives on Union Pacific, like most of America's railroads, used the Whyte classification system for their wheel arrangement, named for Frederick Methvan Whyte.

(click here for more information about the Whyte classification system for steam locomotives)

Steam Locomotive Index
0-6-0	2-6-0	4-4-0	4-6-2	4-8-4	2-8-8-0 Mallet	4-6-6-4
0-8-0	2-8-0	4-4-2	4-8-0	4-10-2	2-8-8-0 Simple	4-8-8-4
	2-8-2	4-6-0	4-8-2	4-12-2	2-8-8-2
	2-10-2

0-6-0 (Switch)

UP’s 298 0-6-0 S-Class switchers were built between 1890 and 1921. Road numbers 4226-4246 were LA&SL locomotives and came to UP in 1921. Numbers 4300-4480, along with the 10 USRA locomotives in the 4600-4909 series, were new to UP. Numbers 5700-4763 were OSL locomotives, and numbers 4900-4933 were O-WR&N locomotives.

Retirements for the pre-Harriman era locomotives started as early as 1913. The Harriman era locomotives, built beginning in 1901, were retired starting in 1925 and continued through to 4466’s retirement in 1962.

S-51	4300-4307, 4310-4347, 4700-4702, 4722-4729, 4900-4901, 4931-4933
S-56	4226
S-57	4227-4228, 4500
S-1	4229-4234, 4350-4359, 4730-4734, 4758, 4927-4930
S-2	4235-4239, 4360-4400, 4703-4721, 4759-4763, 4902-4922
S-3	4240-4242, 4735-4739
S-4	4401-4420, 4740-4744, 4923-4926
S-5	4421-4450, 4748-4752
S-Spec.	4600-4609, 4753-4757
S-6	4243-4246, 4451-4480

0-8-0 (Switch)

S-57

UP 4500

2-6-0 (Mogul)

M-51	4000-4001
M-57	4200-4208
M-62	OSL 4100-4107

2-8-0 (Consolidation)

From 1913 on, UP owned 542 2-8-0s Consolidation-type locomotives. The locomotives were all built between 1888 and 1910, with 19 locomotives, numbers 324-358, coming from the SP in 1910. Beginning with 103 locomotives built in 1901, numbers 401-479, 510-524, and 710-718 series, all 2-8-0 locomotives purchased were built to the Harriman era Common Standard pattern.

The peak years of retirement after 1925 were in 1947, with 92 retired, and again in 1956, with 47 retired.

The last three 2-8-0s on UP were 6264, 6535, and 428. UP 428 was the last operating 2-8-0 and was retired in December 1959. The 6264 and 6535 were the former 264 and 535, renumbered during 1955 and 1956 to avoid conflict with new GP9 diesel units.

These were renumbered at the end of steam into the 6000 series

C-51	100-143, OSL 500-502, 700-706
C-55	510-524, 550-554, 707-709
C-57	150-158, 402-499, 525-539, 710-729
C-2	201-401, 560-622, 730-768

2-8-2 (Mikado; after World War II MacArthur or MacA class)

UP’s 362 2-8-2 Mikado (or MacArthur) type locomotives were built between 1910 and 1921, for itself, the OSL, and the LA&SL. The total remained the same until the retirements started in 1946, except for the 2701, which was sold in 1932.

Although the total quantities didn't change, there had been some swapping between UP and its subsidiaries. In 1918 OSL sent seven locomotives to the LA&SL. In 1920 UP renumbered its USRA series. In 1923 UP sent 18 2-8-2s to the OSL, OSL sent 10 locomotives to the UP, and LA&SL sent 10 2-8-2s to the OSL.

MK-1	1900-1929, 2000-2014, 2100-2140
MK-2	1930-1949, 2015-2034, 2141-2165
MK-8	2166-2171
MK-3	2200-2209
MK-4	2210-2219,
MK-5	2220-2244, 2500-2514, 2726-2732
MK-6	2245-2259, 2700-2708
MK-7	2260-2279, 2515-2514, 2709-2715, 2733-2735
MK-8	2280-2294, 2311-2320, 2525-2534
MK-Spec.	2295-2314, 2535-2554
MK-9	2295-2310
MK-10	2555-2564, 2716-2725

2-10-2 (Two Ten Two)

TTT-1	5000-5009, 5525
TTT-2	5300-5305
TTT-3	5010-5014, 5526-5529
TTT-4	5015-5039
TTT-5	5314-5415
TTT-6	5040-5089, 5306-5313, 5500-5514
TTT-7	5515-5524

4-4-0 (Eight wheeler)

From 1916 on, UP owned 88 4-4-0 American-type locomotives. All were retired by 1936, with only a single locomotive on the roster between 1933 and the final year of 1936.

E-56	1056-1057
E-57	1111
E-61	1000-1001
E-62	900-930, 1002, 1004-1013, 1052-1055, 1122-1123
E-63	1003, 1102-1108
E-64	1114-1121
E-69	931-851, 450, 1058-1061
E-70	1050

4-4-2 (Atlantic)

UP’s 66 4-4-2 Atlantic type locomotives were built between 1903 and 1911. All were retired by the end of 1933. The first group of 4-4-2s to be retired were the 14 Baldwin Vauclain compounds, retired in 1921, with the last two retired in 1923.

UP had 35 locomotives, OSL had 12, LA&SL had 4, and OWRR&N had 15.

A-2	3300-3319, 3400-3411
A-3	3320-3334
A-1	3376-3379
A-4	3500-3514

4-6-0 (Ten Wheeler)

From 1915 on, UP owned a total of 306 4-6-0 Ten-Wheelers. Most were retired by 1946, with one still on the roster. UP 1243 was retained after the second to last Ten-Wheeler was retired in 1955, and is preserved as part of the railroad’s Historical Collection at Cheyenne, Wyoming.

Four 4-6-0s (UP 1584-1587) were acquired by UP from its former subsidiary, Pacific & Idaho Northern, in 1936.

T-1	1755-1760
T-2	1572-1578, 1742-1747
T-3	1579-1583, 1748-1754
T-51	1514-1529
T-54	1502
T-55	1701-1708
T-57	1200-1216, 1222-1225, 1227-1230, 1233-1236, 1239-1247, 1306, 1500-1501, 1540-1561, 1584, 1586-1587, 1733-1741
T-61	1250-1289, 1585
T-62	1226, 1311, 1319, 1503-1513
T-63	1360-1369, 1709-1726
T-64	1727-1732
T-68	1591-1596
T-69	1220-1221, 1231-1232, 1238, 1300-1305, 1307-1310, 1312-1318, 1320-1329, 1534-1539
T-73	1330-1347, 1562-1571
T-79	1348-1359

4-6-2 (Pacific)

UP’s 209 4-6-2 Pacific type locomotives were built between 1903 and 1920. The retirements began as early as 1926 and continued through 1958. UP 3203 was the last 4-6-2 on the railroad. The worst years for retirements were in 1933 (22 retired), 1934 (15 retired) and 1947 (59 retired).

In 1928, two OSL 3100s were transferred to UP 2900s.

P-1	2800-2818, 3150-3170, 3204-3207
P-2	3200-3203
P-3	2819-2824, 3100-3103, 3208-3210
P-4	2825-2828, 3173-3175
P-5	2829-2848
P-6	2850-2859, 3104-3113, 3211-3217
P-7	3218-3219
P-8	2860-2869, 3114-3123, 3176-3181
P-9	2870-2879, 3124-3128
P-10	2880-2899, 2910, 3129-3133
P-11	3134-3138
P-12	3226-3227
P-13	2900-2909, 2911

4-8-0 (Twelve Wheeler)

From 1915 on, UP owned 15 4-8-0 Twelve-Wheelers. The first five were retired in 1925 and the final locomotives were retired in 1928.

TW-57	1800-1807
TW-55	1850-1856

4-8-2 (Mountain)

MT-1	7000-7039, 7850-7864
MT-2	7865-7869

4-8-4 (Four Eight Four)

The 45 FEF (Four-Eight-Four) class locomotives were in three classes. The 20 FEF-1, numbers 800-819, were delivered in 1937. The 15 FEF-2 locomotives, numbers 820-834, were delivered in 1939, and the final 10 FEF-3 locomotives, numbers 835-844, were delivered in 1944, and were the last steam locomotives built new for UP.

FEF-1	800-819
FEF-2	820-834
FEF-3	835-844

4-10-2 (Four Ten Two)

FTT-1	8000
FTT-2	8800-8808

4-12-2 (Union Pacific)

UP-1	9000
UP-2	9001-9014, 9708
UP-3	9015-9029, 9700-9707
UP-4	9030-9054
UP-3	9055-9062
UP-5	9063-9087, 9500-9514

2-8-8-0

UP’s 70 2-8-8-0 Articulated Consolidations were all built between 1918 and 1924 as Mallet Compound, CS Class MC, locomotives. In 1936 the locomotives were rebuilt from compound to simple, with a change in class, from CS Class MC to CS Class SA-C (for Simple Articulated Compound). beginning in 1937, as the rebuilding was completed, they were renumbered from the 3600 class to the 3500 class. The two OSL 3700 class and three OSL 3800 class locomotives were also rebuilt to simple locomotives, but retained their original numbers until 1944 when they were renumbered to the 3500 series to vacate the two number series to make way for the 4-6-6-4 locomotives.

Retirements began in 1947 and continued through 1954.

2-8-8-0 (Mallet Compound)

MC-2	3600-3614, 3644, 3703, 3800-3802
MC-3	3615-3633
MC-4	3634-3638, 3704-3705, 3803-3805
MC-5	3639-3643
MC-6	3645-3664

Class	Built	UP	OSL	OWRR&N	LA&SL
MC 2	1918	UP 3600-3614	OSL 3703
MC 3	1920	UP 3615-3633
MC 4	1922	UP 3634-3638	OSL 3704, 3705*	OWRR&N 3803-3805*
MC 5	1923	UP 3639-3643
MC 6	1924	UP 3645-3664

2-8-8-0 (Simple Articulated - Consolidation)

SA-C-2	3500-3514 (after Atlantics Scrapped)
SA-C-3	3515-3533, 3544, 3565-3569
SA-C-4	3524-3538
SA-C-5	3539-3543
SA-C-6	3545-3564

2-8-8-2 (Simple Articulated and Mallet Compounds)

SA-57	3570-3588 (ex C&O H-7)
SA-57	3589-3599 (ex C&O H-7a)
MC-57	3670-3674 (ex N&W Y-3)

4-6-6-4 (Challenger Simple Articulated)

CSA-1	3801-3814; renumbered from 3900 class
CSA-2	3815-3839; renumbered from 3900 class
4664-5	3930-3949
4664-3	3950-3969
4664-4	3969-3999

4-8-8-4 (Big Boy)

4884-1	4000-4019
4884-2	4020-4024

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