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Union Pacific Steam Locomotive Wheel Arrangements

Index For This Page

This page was last updated on August 25, 2016.

(Return to UP Steam Locomotive Roster Index)

(Return to UP Steam Locomotives Index Page)

(This is a work in progress since April 1996; research continues.)

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.

(Read the Wikipedia article about the Whyte classification system for steam locomotives)

0-6-0 Class S

(Switch)

Total of 303 locomotives

UP's 303 0-6-0 S-Class switchers were built between 1890 and 1921, in the following series:

The S-51, S-55 and S-56 classes (62 total) were built before the Harriman Common Standard era, built in 1887-1902.

The S-1 to S-6 classes (226 total) were the Harriman Common Standard designs, built in 1904-1920.

The Special classes (15 total) were USRA design, built in 1918-1919.

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.

Class Last Assigned Number Qty.
S-56 LA&SL 4226 (1) 1
S-55 LA&SL 4227-4228 (2) 2
S-1 LA&SL 4229-4234 (6) 6
S-2 LA&SL 4235-4239 (5) 5
S-3

LA&SL 4240-4242 (3)

3
S-6 LA&SL 4243-4246 (4) 4
S-51 UP 4300-4307 (8), UP 4310-4347 (38) 46
S-1 UP 4350-4359 (10) 10
S-2 UP 4360-4400 (41) 41
S-4 UP 4401-4420 (20) 20
S-5 UP 4421-4450 (30) 30
S-6 UP 4451-4480 (30) 30
S-Spec. UP 4600-4609 (10) 10
S-51 OSL 4700-4702 (3), OSL 4725-4729 (5) 8
S-2 OSL 4703-4724 (22), OSL 4759-4763 (5) 27
S-1 OSL 4730-4734 (5), OSL 4758 (1) 6
S-3

OSL 4735-4739 (5)

5
S-4 OSL 4740-4744 (5) 5
S-5 OSL 4748-4752 (5) 5
S-Spec. OSL 4753-4757 (5) 5
S-51 OWRR&N 4900-4901 (2), OWRR&N 4931-4933 (3) 5
S-2 OWRR&N 4902-4922 (21) 21
S-4 OWRR&N 4923-4926 (4) 4
S-1 OWRR&N 4927-4930 (4) 4
    303
Class Last Assigned Number Qty.
S-51 UP 4300-4307 (8), UP 4310-4347 (38) 46
S-51 OSL 4700-4702 (3), OSL 4725-4729 (5) 8
S-51 OWRR&N 4900-4901 (2), OWRR&N 4931-4933 (3) 5
S-55 LA&SL 4227-4228 (2) 2
S-56 LA&SL 4226 (1) 1
S-1 LA&SL 4229-4234 (6) 6
S-1 UP 4350-4359 (10) 10
S-1 OSL 4730-4734 (5), OSL 4758 (1) 6
S-1 OWRR&N 4927-4930 (4) 4
S-2 LA&SL 4235-4239 (5) 5
S-2 UP 4360-4400 (41) 41
S-2 OSL 4703-4724 (22), OSL 4759-4763 (5) 27
S-2 OWRR&N 4902-4922 (21) 21
S-3

LA&SL 4240-4242 (3)

3
S-3

OSL 4735-4739 (5)

5
S-4 UP 4401-4420 (20) 20
S-4 OSL 4740-4744 (5) 5
S-4 OWRR&N 4923-4926 (4) 4
S-5 UP 4421-4450 (30) 30
S-5 OSL 4748-4752 (5) 5
S-6 LA&SL 4243-4246 (4) 4
S-6 UP 4451-4480 (30) 30
S-Spec. UP 4600-4609 (10) 10
S-Spec. OSL 4753-4757 (5) 5
    303

0-8-0 Class S

(Switch)

S-57 UP 4500

2-6-0 Class M

(Mogul)

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

2-8-0 Class C

(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 Class MK

(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 Class TTT

(Two Ten Two)

Total of 144 locomotives.

CS Class Last Assigned Number Qty.
TTT-1 UP 5000-5006, 5008, 5009 (9), LA&SL 5525 (1) 10
TTT-2 OSL 5300-5305 (6) 6
TTT-3 UP 5014 (1), LA&SL 5526-5529 (4) 5
TTT-4 UP 5015-5039 (25) 25
TTT-5 OSL 5314-5318 (5) OWRR&N 5400-5407, 5410, 5414 (10) 15
TTT-6 UP 5040-5089 (50), OSL 5306-5313 (8), LA&SL 5500-5514 (15) 73
TTT-7 LA&SL 5515-5524 (10) 10
    144

4-4-0 Class E

(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 Class A

(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 Class T

(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 Class P

(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.

OWRR&N 3203 was the last P-class locomotive to be retired, in January 1958; as of September 2015, being restored by the Friends of OR&N 197 at Oregon Rail Heritage Foundation in Portland, Oregon.

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

(Read more about two-tone gray and other features on UP's 4-6-2 Pacific locomotives)

4-8-0 Class TW

(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 Class MT

(Mountain)

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

(Read more about two-tone gray and other features on UP's 7000-class 4-8-2 Mountain locomotives)

4-8-4 Class FEF

(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

(Read more about two-tone gray and other features on UP's 800-class 4-8-4 Northern locomotives)

(Read more about the use of UP's 800-class 4-8-4 Northerns on Cajon Pass in Southern California)

4-10-2 Class FTT

(Four Ten Two)

FTT-1 8000
FTT-2 8800-8808

4-12-2 Class UP

(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 Class MC

(Mallet Compound)

UP's 70 2-8-8-0 Articulated Consolidations were all built between 1918 and 1924 as CS Class MC (Mallet Compound) locomotives.

(Also in 1918, Utah Railway received three 2-8-8-0 locomotives, ordered in late 1916 by the Union Pacific Equipment Association. Utah Railway had asked for UP's assistance in the design of these locomotives, with Utah Railway soon to assume the operation of its own trains. UP evaluated the available designs, and determined that the design of fifteen B&O EL-series delivered in 1916 was a good match for the projected and similar service slow speed coal drags on Utah Railway. These three Utah Railway locomotives were very similar to later UP's MC-class, but were built by Baldwin and were about 12,000 pounds lighter (weight on drivers) than the sixteen locomotives delivered in 1918 to UP and OSL. Utah Railway used MC-2 as the class for their locomotives, the same as UP's class.)

Beginning in 1936 the locomotives were rebuilt from compound to simple, with a change in class, from CS Class MC to CS Class SA-C (Simple Articulated Compound). Beginning in 1937, as the rebuilding was completed, they were renumbered from the 3600 class, to the 3500 class (after the 3500-class 4-4-2 Atlantics were scrapped).

The three OSL 3700 class and three OWRR&N 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.

Class Built Qty. UP OSL OWRR&N
MC-2 1918 16 UP 3600-3614 OSL 3703  
MC-3 1920 19 UP 3615-3633    
MC-4 1922 10 UP 3634-3638 OSL 3704, 3705 OWRR&N 3803-3805
MC-5 1923 5 UP 3639-3643    
MC-6 1924 20 UP 3645-3664    
    70      

2-8-8-0 Class SAC

(Simple Articulated - Consolidation)

Retirements began in 1947 and continued through 1954.

Class Qty. UP OSL OWRR&N
SA-C-2 15 UP 3500-3514    
SA-C-3 25 UP 3515-3533, UP 3544 (ex OSL 3703) OSL 3565, 3566 OWRR&N 3567-3569
SA-C-4 15 UP 3524-3538    
SA-C-5 5 UP 3539-3543    
SA-C-6 20 UP 3545-3564    
  70      

2-8-8-2 Class SA and MC

(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 Class CSA

(Challenger Simple Articulated)

CSA-1 3801-3814; renumbered from 3900 class
CSA-2 3815-3839; renumbered from 3900 class

4-6-6-4 Class 4664

(Four Six Six Four)

4664-5 3930-3949
4664-3 3950-3969
4664-4 3975-3999

(Read more about two-tone gray and other features on UP's 3900-class 4-6-6-4 Challenger locomotives)

4-8-8-4 Class 4884

(Four Eight Eight Four) (Big Boy)

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

"Santa Fe employee timetables from 1947 show speed and track restrictions for UP 4000s on the Santa Fe between Daggett and Riverside Junction, but there's no evidence that it ever happened when the engines were in revenue service. There were lots of active railfans in Southern California back then, including several who were railroaders on the ATSF and the UP, and I doubt if a Big Boy steaming into East LA would have escaped their notice." (Andy Sperandeo, email to UP Modelers Yahoo discussion group, January 10, 2005)

Sources

Initial research completed in mid April 1996

Additional information taken from research compiled by Rick Steel, posted on August 21, 1998 to the now-defunct Streamliner email discussion group, in response to a query from John A. Thompson about Union Pacific's steam locomotive class designations.

Gordon McCulloch's "A History Of Union Pacific Steam" book, published in 2012.

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