Oregon Short Line / Union Pacific / Oregon Washington Railroad & Navigation 2-8-2 "Mikado" Type Locomotives

Introduction

The Union Pacific Railroad headquartered in Omaha, Nebraska, is now the largest railroad network in the United States. UP's route map covers most of the central and western United States west of Chicago and New Orleans. As of December 31, 2008 UP operates on 32,012miles of track, of which it owns outright 26,171miles. Both numbers represent the highest amount of any railroad currently operating in the United States. It has achieved this size as a result of purchasing a large number of other railroads, notably the Missouri Pacific, Chicago and North Western, Western Pacific, Missouri-Kansas-Texas, and the Southern Pacific.

At the beginning of the 20th Century the Union Pacific's main lines ran from Council Bluffs, IA west to Ogden, UT and from Kansas City, MO west to Denver, CO then North to Cheyenne, WY. The Oregon Short Line a subsidiary of the UP extended from Granger, WY Northwest to Huntington, OR. The OSL other main lines reached Pocatello, ID, Silver Bow MT and ran from McCummon, ID through Ogden, Salt lake City and on to Uvada, UT. Another UP subsidiary the Oregon-Washington Railroad & Navigation Company ran from Huntington, OR to Portland and Umatilla, OR then to Spokane, WA. In 1907, another UP subsidiary the Los Angeles & Salk Lake was completed and added a mine line from Los Angeles, CA to Salt Lake City, UT

The UP and it subsidiaries bought a total of 362 "Mikado" type locomotives. The Baldwin Locomotive Works built 263 of them, 74 came from the American Locomotive Company and the Lima Locomotive Works delivered 25 of them. The USRA allocated twenty "Mikado-lights" to the UP and another twenty to the OSL. The USRA locomotives came in 1918 and 1919. These locomotives had 63" diameter drivers, 26" x 30" cylinders, a 200 psi boiler pressure, they exerted 54,725 pounds of tractive effort and each weighed 290,800 pounds. The firebox was 280 square feet, the evaporative heating surface was 3,783 square feet and with the superheater the combined heating surface was 4,665 square feet.

The first "Mikado" type locomotive on the UP was a single locomotive delivered to the OWR&N in 1910. This locomotive was built by the Baldwin Locomotive Works and it had 57" diameter drivers, 23 ¾" x 30" cylinders, a 190 psi boiler pressure, they exerted 47,945 pounds of tractive effort and each weighed 267,850 pounds. The firebox was 267 square feet, the evaporative heating surface was 5,559 square feet and there was no superheater

This locomotive design was the standard used for the next 150 "Mikados" bought with 57" diameter drivers for the UP, OSL, OWR&N and the LA-SL during 1911, 1912 and 1913. They were divided into two classes, MK-1 and MK-2 with road numbers assigned to suite each road.

In 1911, the UP ordered ten 2-8-2s with 63" diameter drivers and 26"x 28" cylinders. These locomotives were designated as Class MK-3 and assigned UP road numbers 2200 through 2209. With a 210 psi boiler pressure they exerted 53,628 pounds of tractive effort and each weighed 288,700 pounds. The fire box was 267 square feet, the evaporative heating surface was 5,559 square feet and there was not superheater.

This locomotive set the UP standard for all of the 172 "Mikados" bought with 63" diameter drivers for all of the UP roads.

There are four surviving Union Pacific 2-8-2 "Mikado" type locomotives. These four locomotives are numbers 2005, 2295, 2537 and 2564. Number 2005 was a Class MK-1 built by Baldwin in 1911. It served on the OSL until retired in the early 1950.s and is on display at Ross Park in Pocatello, ID. Number 2295 was built by ALCO in 1918 and saw service wearing Union Pacific livery until retired in the late 1950s. It is on static display at Boise depot in Boise, ID. Number 2537 was a USRA allocated locomotive and is on display at Jefferson Park in Walla Walla, WA. Number 2564 a Class MK-10 saw service on both the LA&SL and the OSL. It is on display at the Orange Empire Railway Museum in Perris, CA.

Roster by Richard Duley

ClassQty.Road NumbersRoadFrom Other RoadsYear AcquiredYear BuiltBuilderNotes
MK-1301900-1929UP1911Baldwin1
MK-1152000-2014OSL1911Baldwin2
MK-1 12100OWR&N1910Baldwin3
MK-1402101-2140OWR&N1911Baldwin4
MK-2201930-1949UP1912Baldwin5
MK-2202015-2034OSL1912Baldwin6
MK-2152141-2155OWR&N1912Baldwin7
MK-2102156-2165OWR&N1913Baldwin7
MK-3102200-2209UP1911Baldwin8
MK-4102210-2219UP1912Baldwin9
MK-4 42515-2518OSLEx UP 19231912Baldwin10
MK-5252220-2244UP1913Baldwin11
MK-5152500-2514OSL1913Baldwin12
MK-5 62519-2524OSLEx UP19231913Baldwin13
MK-5 72726-2732LA&SLEx OSL19231913Baldwin14
MK-6152245-2259UP1914Lima15
MK-6 32525-2527 OSLEx UP19231914Lima16
MK-6 82700-2707LA&SL1914ALCO17
MK-6 12708LA&SL1914Baldwin18
MK-7202260-2279UP1917Baldwin19
MK-7102515-2524OSL1917Lima20
MK-7 52528-2532OSLEx UP19231917Baldwin21
MK-7 72709-2715LA&SLEx OSL19181917Lima22
MK-7 32733-2735LA&SLEx OSL19231917Lima23
MK- Special202480-2499UP1918ALCO24
MK- Special202535-2554OSL1918-1919ALCO25
MK-8152280-2294UP1918Baldwin26
MK-8 62166-2171OWR&N1918Baldwin27
MK-8102525-2534OSL1918Baldwin28
MK-8102311-2320UPEx OSL19231918Baldwin29
MK-9162295-2310UP1918ALCO30
MK-10102716-2725LA&SL1921ALCO31
MK-10102555-2564OSLEx LA&SL19231921ALCO32
Notes:
  1. Numbers 1900-1929. Built as number 500-529 renumbered in 1915 to 1900-1929. Numbers 1900, 1912, 1923, 1924 and 1925 were oil fired the others burned coal. Numbers 1913, 1915, 1917 1919 and 1928 were equipped with a duplex stocker which increased the weight by 1,550 pounds. Number 1917 sold to the Spokane International in 1917. Nineteen scrapped in 1947 through 1949 and the others were scrapped between 1953 and 1957
  2. Numbers 2000-2014. Built as number 1100-1114 renumbered in 1915 to 2000-2014. Numbers 2001, 2008, and 2013 were oil fired the others burned coal. Numbers 2000, 2003, 2005, 2006, 2007, 2012 and 2014 were equipped with a duplex stocker which increased the weight by 1,550 pounds. Number 1917 sold to the Spokane International in 1917. Number 2000 sold to the Spokane International in 1936. Number 2005 is preserved. Six scrapped in 1947 through 1948, Number 2003 scrapped in 1952 and the others were scrapped between 1954 and 1958
  3. Number 2100 was built as number 440, renumbered 500 in 1911 and then renumbered 2100 in 1915. It was oil fired. Scrapped in 1955
  4. Numbers 2101-2140. Built as number 501-540 renumbered in 1915 to 2101-2140. Numbers 2101, 2103-2106, 2108, 2109, 2111-2114, 2116, 2118-2121, 2123, 2124, 2129, 2132-2136, 2138 and 2140 were oil fired the others burned coal. Numbers 2103 and 2138 were equipped with a booster trailing truck adding 10,500 pounds to the maximum tractive effort. Sixteen scrapped in 1946 through 1949. Number 2103 was scrapped in 1951 and the others were scrapped between 1953 and 1957.
  5. Numbers 1930-1949. Built as numbers 530-549 renumbered in 1915 to 1930-1949. Numbers 1931, 1938, and 1948 were oil fired the others burned coal. Numbers 1930, 1932 through 1937, 1939 through 1946 were equipped with a duplex stocker which increased the weight by 1,550 pounds. Number 1936 sold to the Spokane International in 1936. Four scrapped in 1947 through 1949 and the others were scrapped between 1953 and 1958
  6. Numbers 2015-2034. Built as number 1115-1134 renumbered in 1915 to 2015-2034. Number 2020 was oil fired the others burned coal. Numbers 2016, 2018, 2019, 2021, 2025 and 2030 through 2034 were equipped with a duplex stocker which increased the weight by 1,550 pounds. Number 1936. Four scrapped in 1947 through 1949 and the others were scrapped between 1953 and 1958.
  7. Numbers 2141-2165. Built as numbers 541-565 renumbered in 1915 to 2141-2165. Numbers 2145, 2147-2157, 2159, 2161, and 2163-2165 were oil fired the others burned coal. Numbers 2147, 2149, 2152, 2152 and 2154 were equipped with a tender booster in 1926 which was removed between 1916 and 1939. Numbers 2149, 2152, 2152 and 2154 were equipped with a booster trailing truck adding 10,500 pounds to the maximum tractive effort. Number 2165 was equipped with train signals and steam heating for passenger service adding 5,000 pounds to the locomotive weight and 4,000 pounds to the tender weight. Thirteen were scrapped in 1947-1949 and the others were scrapped between 1953 and 1959. .
  8. Numbers 2200-2209. Built as numbers 700-709 renumbered in 1915 to 2200-2209. Numbers 2200 and 2202 were coal burners and the others burned oil. Number 2200 scrapped in 1947, Number 2205 scrapped in 1949. The others were scrapped between 1954 and 1957.
  9. Numbers 2210-2219. Built as numbers 710-719 and renumbered in 1915 to 2210-2219. Numbers 2214, 2215, 2217 & 2218 transferred to the OSL in 1923 and became OSL numbers 2525-2518. Numbers 2212 and 2216 scrapped in 1948. The others were scrapped between 1954 and 1956..
  10. Numbers 2515-2518. Built as UP numbers 714, 715, 717 and 718 in 1912 renumbered to UP 2214, 2215, 2217 and 2218 in 1915. Transferred to the OSL in 1923 and became OSL numbers 2515-2518. Ex UP 2214, 2215, 2217 and 2218. Number 2518 scrapped in 1947, Number 2516 scrapped in 1955. Numbers 2515 and 2517 scrapped in 1956.
  11. Numbers 2220-2244. Built as numbers 720-744 renumbered in 1915 to 2220-2244. Numbers 2220, 2224, 2225, 2228, 2233 and 2241 were transferred to the OSL in 1923 and became OSL numbers 2519-2524. Numbers 2227, 2234 and 2237-2240 scrapped in 1947. Numbers 2222, 2229, 2232 and 2243 scrapped in 1948. The others were scrapped between 1953 and 1958.
  12. Numbers 2500-2514. Built as numbers 1200-1214 renumbered in 1915 to 2500-2514. Numbers 2500-2503, 2505, 2509 and 2514 transferred to the LA&SL in 1923 and became LA&SL numbers 2726-2732. Numbers 2508 and 2512 scrapped in 1947. Number 2513 scrapped in 1948. Number 2506 scrapped in 1949. The others were scrapped between 1952 and 1956.
  13. Numbers 2419-2524. Built as UP numbers 720, 724, 725, 728, 733 and 741 and renumbered to UP 2220, 2224, 2225, 2228. 2233 and 2241 in 1915. Transferred to the OSL in 1923 and became OSL numbers 2519-2524. Number 2523 scrapped in 1946. Number 2522 scrapped in 1947. Number 2524 scrapped in 1954. Number 2519 scrapped in 1956. Number 2520 scrapped in 1957. Number 2521 scrapped in 1958.
  14. Numbers 2726-2732. Built as OSL numbers 1200-1214 renumbered OSL 2500-2514 in 1921. Transferred to the LA&SL in 1923 and became LA&SL numbers 2726-2732. Number 2732 was sold to Six Companies in 1932 for use in the construction of Boulder Dam. It was sold back in March of 1936 and scrapped in 1947. Numbers 2727 and 2729 scrapped in 1948. Numbers 2726, 2728 and 2730 scrapped in 1956. Number 2731 scrapped in 1957.
  15. Numbers 2245-2259. Built as numbers 745-759 renumbered in 1915 to 2245-2259. Numbers 2246, 2254 and 2258 were transferred to the OSL and became OSL numbers 2525-2527. Numbers 2247, 2255 and 2256 scrapped in 1947. Numbers 2248, 2249 and 2251 scrapped in 1948. The others were scrapped between 1954 and 1957.
  16. Numbers 2525-2527. Built as UP 746, 754 and 758 and renumbered to UP 2246, 2254 and 2258 in 1915. Transferred to the OSL in 1923 and became OSL numbers 2525-2527. Number 2526 scrapped in 1949. Number 2527 scrapped in 1950. Number 2525 scrapped in 1954.
  17. Numbers 2700-2707. Built as LA&SL numbers 3700-3707 and renumbered 2700-2707 in 1921. Numbers 2700, 2706 and 2705 scrapped in 1947. Number 2701 and 2707 sold to Six Companies for use in the construction of Boulder Dam. Number 2707 was sold back to the UP in 1936. Number 2707 scrapped in 1948. Numbers 2702 and 2704 scrapped in 1955. Number 2703 scrapped in 1956.
  18. Number 2708. Built as LA&SL number 3708 and renumbered 2708 in 1921. It was scrapped in 1947.
  19. Numbers 2260-2279. Numbers 2266, 2268, 2275, 2277 and 2278 transferred to the OSL and became OSL 2528-2532 in 1923. Numbers 2260 and 2261 transferred to the O&NR in 1947. Numbers 2260, 2261, 2271 and 2274 scrapped in 1947. Numbers 2273 and 2276 scrapped in 1948. The others scrapped between 1953 and 1958.
  20. Numbers 2515-2524 Numbers 2515, 2516, 2519, 2520, 2522, 2523 and 2524 transferred to the LA&SL in 1918 and became LA&SL numbers 2709-2715. Numbers 2517, 2518 and 2521 transferred to the LA&SL in 1923 and became LA&SL numbers 2733-2735.
  21. Numbers 2528-2532. Built as UP numbers 2266, 2268, 2275, 2277 and 2278 Transferred to the OSL in 1923 and became OSL numbers 2528-2532 Number 2530 scrapped in 1947. Numbers 2531 and 2532 scrapped in 1948. Numbers 2528 and 2529 scrapped in 1956.
  22. Numbers 2709-2715. Built as OSL 2515-2524 in 1917. Transferred to the LA&SL in 1918 and were numbered LA&SL 3709-3715 and then renumbered the same year as LA&SL 2709-2715. Number 2712 scrapped in 1947. Numbers 2710, 2713 and 2715 scrapped in 1954. Number 2709 scrapped in 1955. Number 2714 scrapped in 1956. number 2711 scrapped in 1957.
  23. Numbers 2733-2735. Built as OSL numbers 2517, 2518 and 2521. Transferred to the LA&SL in 1923 and became LA&SL 2733-2735. Number 2735 scrapped in 1948. Number 2734 Scrapped in 1953. Number 2733 scrapped in 1958.
  24. Numbers 2480-2499 USRA allocated locomotives. They were delivered with road numbers 2295-2314 and renumbered 2480-2499 in 1920. All were scrapped between 1953 and 1958.
  25. Numbers 2535-2554 USRA allocated locomotives. Number 2537 is preserved. Numbers 2536 and 2538 were wrecked in 1946 and scrapped. Number 2542 scrapped in 1948. Number 2553 scrapped in 1949. The others were scrapped between 1953 and 1957.
  26. Numbers 2280-2294. Numbers 2280, 2290 and 2293 were oil fired the others burned coal. Numbers 2284 and 2293 scrapped in 1947. Numbers 2291 scrapped in 1949. The others were scrapped between 1954 and 1956.
  27. Numbers 2166-2171. All were oil fired. Numbers 2166-2168 were equipped with train signals and steam heating for passenger service. Numbers 2169, 2170 and 2171 were equipped with a tender booster, which were removed during 1936-1939. Numbers 2169-2171 were equipped with a booster trailing truck which added 10,500 pounds to the maximum tractive effort. Number 2166 wrecked in 1947 and it and number 2169 were scrapped that year. Number 2170 scrapped in 1954. Numbers 2167, 2171 scrapped in 1956. Number 2168 scrapped in 1957.
  28. Numbers 2525-2534. All were transferred to the UP in 1923 and became UP numbers 2311-2320.
  29. Numbers 2311-2320. Built as OSL numbers 2525-2534 in 1918 Transferred to the UP in 1923 and became UP numbers 2311-2320. Numbers 2313 and 2319 scrapped in 1947. number 2311 scrapped in 1949. The others were scrapped between 1954 and 1956.
  30. Numbers 2295-2310. Number 2295 is preserved. Numbers 2296, 2299, 2300 and 2301 scrapped in 1947. Numbers 2203 and 2308 scrapped in 1948. Number 2305 scrapped in 1950. The others scrapped between 1953 and 1959.
  31. Numbers 2716-2725. Built as LA&SL numbers 3716-3725 renumbered to LA&SL 2716-2725 in 1921. Transferred to the OSL in 1923 and became OSL numbers 2555-2564.
  32. Numbers 2555-2564.Built as LA&SL numbers 2716-2725 renumbered to SL&SL 2716-2725. Transferred to the OSL in 1923 and became OSL numbers 2555-2564. Number 2564 is preserved. Number 2563 scrapped in 1947. The others scrapped between 1954 and 1957.

Class Details by Steve Llanso

Class MK - Spl (Locobase 6608)

Data from 1936 Union Pacific locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

Locobase reproduces this basic USRA light Mike design as modified by the Union Pacific to illustrate how the locomotives were updated during the next few decades.

Some of the class were fitted with Nicholson thermic syphons. The design retained 13.5 sq ft of arch tubes while the syphons themselves represented 78 sq ft of firebox heating surface. With other changes, the total increase in firebox heating surface totalled 57.5 sq ft or 20%. That was a healthy slug of new power achieved by concentrating on the part of the heat generator that would benefit most from a change.

Class MK 1/MK 2/MK-3 - superheated (Locobase 6607)

Data from 1936 Union Pacific locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

This was the more powerful class of Mikados in its saturated state (Locobase 38). It wasn't long before the railroad was superheating those Mikes it hadn't bought with superheaters. The upgrade dried the steam, but otherwise little changed the overall balance.

Eight of the ten MK-3s were converted to oil burning; these had no grate area and no arch tubes and trailed tenders carrying 9,000-10,000 US gallons of water and 3,750 US gallons of oil.

Class MK-1 (Locobase 1405)

Data from UP's 1918 Locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection. See also "Simple 2-8-2 for Oregon Railroad Navigation Co.," Railroad and Locomotive Engineering, Vol 23, No 10 (October 1910), pp. 417-418; and "Powerful Lignite Burner of the Mikado Type", American Engineer and Railroad Journal (October 1910), pp. 404-406

MK-1 and MK-2 -- all Baldwin-built -- represent the first of two principal Mikado designs that EH Harriman settled on to standardize his locomotive stud. The first Harriman 2-8-2 was OR&N's 2100. Later engines had squarer cylinder dimensions (see Locobase 38).

But the big difference between this Mike design and several others that were entering service at the same time was its provision for burning low-calorie lignite coal. As a result, the a radial-stay boiler was substituted for the usual crown-bar boiler. The AERJ article comments that the size of the boiler is such that were it to use a good-quality bituminous coal, the engine would be considered "over-boilered." Incorporating the experience of burning lignite in Chicago, Burlington & Quincy locomotives, the grate had many narrow openings and a high-mounted firebrick arch to soften the pull of the draft on the coal bed. Smokebox differences included a large area, fine netting to catch sparks, and a low-mounted nozzle and bell-mouthed extension on the stack.

AERJ notes that in all other respects, this class of 2-8-2s followed Associated Lines designs, including 25" pistons bushed to 23 3/4", 12" piston valves with 1/4" lead.

MK-1s went to UP (30 in 1911), Oregon Short Line (15 in 1911) , and Oregon Washington Railroad & Navigation (41 1910 & 1911). MK-2s followed for UP (20 in 1912), Oregon Short Line (20 in 1912), and OWR&N (25 in 1912-1913). Works numbers were

1910

July 34978 (OWR&N)

1911

March 36227-36236 (UP), 36237-36246, 36322-36329 (OWR&N), 36277-36280 (OSL)

April 36281, 36362-36371 (OSL), 36330-36351 (OWR&N), 36352-36361, 36448-36451 (UP)

May 36517-36521 (UP)

September 38293-38294, 38328-38334, 38356-38361 (OWR&N).

Retirements began in 1947.

Class MK-1 - superheated (Locobase 6605)

Data from 1936 Union Pacific locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection. For new construction, works numbers were 38362-38363, 38385-38386 in September 1912; 38421-38425, 38490-38500 in October 1912 (UP); 38543-38562 in October (Oregon Short Line).

After 80 of the saturated-boiler MK-1s were delivered to the various Associated Lines in 1910-1911 (Locobase 1405), Baldwin began producing superheated versions. Superheating the MK-1 Mikado class seems to have consumed a surprising amount of space. From 495 2" tubes in the saturated boiler, the new design traded 220 tubes for 36 superheater flues. One could argue that the original design was over-endowed. The firebox heating surface area included 32.2 sq ft of "fire brick" arch tubes.

Most of the MK-1s and all of the sextet of OWRRN MK-2s were so modified. Some had had their arch tubes deleted by 1946 during their conversions to oil-firing. Their tenders carried 3,750 US gallons of oil.

Class MK-2 (Locobase 14089)

Data from DeGolyer, Vol 46, 51. Works numbers were 39905-39914 in May 1913.

This class had only detail differences from the Mk1s shown in Locobase 6605. The first 10 were renumbered in 1915 when the OWR & N was integrated into the UP's motive power roster.

All ten engines served the UP throughout World War II. The 2163 was the first to be retired in May 1947 while 2157 was the last more than a decade later in January 1958.

Class MK-3 (Locobase 38)

Data from UP 5-1918 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 36511-36515, 36562-36563, 36573-36575 in May 1911.

Relatively high-boilered type that differed from the earlier MK-1/MK-2 (Locobase 1405) in having squarer cylinder dimensions and taller drivers; one of two principal designs that EH Harriman settled on to standardize his Associated Lines locomotive stud.

Locobase 6607 describes the superheated upgrade that was very shortly applied to this class.

Retirements began in 1947.

Class MK-4 (Locobase 14239)

Data from DeGolyer, Vol 46, pp. 81+. Works numbers were 36511-36515, 36562-36575 in May 1911.

These were the first Baldwin Mikes for the UP that were delivered with superheaters in what was now the standard 2-8-2 design for that road.

All of the Mk-4s remained with the UP. 2200 was the first to be retired in October 1947. 2206 outlasted almost all of the other 2-8-2s, being retired only in December 1957.

Class MK-5 (Locobase 14237)

Data from DeGolyer, Vol 46, pp. 81+. Works numbers were 39587-39607, 39674-39677 in April 1913.

These were the first Baldwin Mikes for the UP that were delivered with superheaters in what was now the standard 2-8-2 design for that road. Four--2224-2225, 2228, and 2233--were sold to subsidiary Oregon Short Line in 1923 as that road's 2520-2523.

Of the Mk-4s that remained with the UP, 2237 was the first to be retired in March 1947. The last to be delivered--2244-- was the last retired in May 1956.

Class MK-5 (Locobase 14238)

Data from DeGolyer, Vol 46, pp. 81+. Works numbers were 39587-39607, 39674-39677 in April 1913.

These were the first Baldwin Mikes for the UP that were delivered with superheaters in what was now the standard 2-8-2 design for that road. Four--2224-2225, 2228, and 2233--were sold to subsidiary Oregon Short Line in 1923 as that road's 2520-2523.

Of the Mk-4s that remained with the UP, 2237 was the first to be retired in March 1947. The last to be delivered--2244-- was the last retired in May 1956.

Class MK-6 (Locobase 14243)

Data from DeGolyer, Vol 46, pp. 81+. See also UP - 5- 1918 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 36511-36515, 36562-36575 in May 1911.

Lima Locomotive Works' first Mikados for the Union Pacific repeated the power dimensions, weights, and areas of the Baldwins that had arrived in 1912 (Locobase 14239). Lima's fifteen were supplemented by ten delivered to subsidiary Los Angeles & Salt Lake. Alco built 9, Baldwin 1. "

Class MK-7/MK- 8/MK-9 (Locobase 11022)

Data from Record of Recent Construction #98 (Baldwin Locomotive Works, 1920), p. 19. See also DeGolyer, Vol 56, pp. 217+.

1917

June 45765-45768, 45830, 45841-45843; July 45927-45929, 45987-45988, 45999-46000; August 46155, 46161, 46172, 46212

1918

March 48080, 48143; April 48290-48293; May 48523, 48572, 48677-48678, 48734, 48777; June 48894, 48954, 48996

This class was delivered with superheaters. Nearly square cylinders received their steam through 15" (381 mm) piston valves.

With few exceptions, the thirty engines operated on the UP until the 1950s. In 1923, however, five were sold to the UP's Oregon Short Line subsidiary; 2266, 2268, 2275, 2277-2278 became 2528-2532.

The Oregon Washington Railroad & Navigation sold 2260-2261 to the Oregon & Northwestern in February 1947.


Specifications by Steve Llanso
ClassMK - SplMK 1/MK 2/MK-3 - superheatedMK-1MK-1 - superheatedMK-2MK-3MK-4MK-5MK-5MK-6MK-7/MK- 8/MK-9
Locobase ID6608 6607 1405 6605 14089 38 14239 14237 14238 14243 11022
RailroadUnion Pacific (UP)Union Pacific (UP)Union Pacific (UP)Union Pacific (UP)Oregon Washington Railroad & Navigation (UP)Union Pacific (UP)Union Pacific (UP)Union Pacific (UP)Oregon Short Line (UP)Union Pacific (UP)Union Pacific (UP)
Whyte2-8-22-8-22-8-22-8-22-8-22-8-22-8-22-8-22-8-22-8-22-8-2
Road Numbers2480-2499, 2535-25541900-21551900-21551900-1949, 2000-2034556-565 / 2156-21652200-22092210-2219720-744 / 2220-22442500-25142240-2259, 2700-27092260-2310, 2515-
GaugeStdStdStdStdStdStdStdStdStdStdStd
BuilderAlco-SchenectadyShopsBaldwinShopsBaldwinBaldwinBaldwinBaldwinBaldwinseveralBaldwin
Year19181918191019121913191119121913191319151917
Valve GearWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase16.80'16'16'16'16'16.50'16.50'16.50'16.50'16.50'16.50'
Engine Wheelbase36.10'35.17'34.67'34.67'34.67'35.17'35.17'35.17'35.17'35.17'35.17'
Ratio of driving wheelbase to overall engine wheebase 0.47 0.45 0.46 0.46 0.46 0.47 0.47 0.47 0.47 0.47 0.47
Overall Wheelbase (engine & tender)71.38'69.76'64.60'64.60'64.60'65.10'69.78'69.78'69.78'70.83'69.78'
Axle Loading (Maximum Weight per Axle)55000 lbs55450 lbs55000 lbs52500 lbs52500 lbs56450 lbs56450 lbs56450 lbs
Weight on Drivers221500 lbs214050 lbs205425 lbs206200 lbs206200 lbs214050 lbs214050 lbs217800 lbs217800 lbs214050 lbs219400 lbs
Engine Weight290800 lbs286117 lbs263000 lbs265600 lbs265600 lbs276750 lbs286117 lbs285100 lbs285100 lbs286117 lbs282800 lbs
Tender Light Weight188300 lbs159100 lbs167700 lbs167700 lbs167700 lbs170500 lbs167200 lbs167200 lbs167200 lbs159100 lbs167200 lbs
Total Engine and Tender Weight479100 lbs445217 lbs430700 lbs433300 lbs433300 lbs447250 lbs453317 lbs452300 lbs452300 lbs445217 lbs450000 lbs
Tender Water Capacity10000 gals10000 gals9000 gals9000 gals9000 gals9000 gals9000 gals9000 gals9000 gals9000 gals9000 gals
Tender Fuel Capacity (oil/coal)16 tons17 tons15 tons15 tons15 tons15 tons14 tons14 tons14 tons14 tons14 tons
Minimum weight of rail (calculated) on which locomotive could run92 lb/yard89 lb/yard86 lb/yard86 lb/yard86 lb/yard89 lb/yard89 lb/yard91 lb/yard91 lb/yard89 lb/yard91 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter63"63"57"57"57"63"63"63"63"63"63"
Boiler Pressure200 psi210 psi190 psi190 psi180 psi200 psi200 psi200 psi200 psi200 psi200 psi
Cylinders (dia x stroke)26" x 30"26" x 28"23.75" x 30"23.75" x 30"23.75" x 30"26" x 28"26" x 28"26" x 28"26" x 28"26" x 28"26" x 28"
Tractive Effort54724 lbs53629 lbs47945 lbs47945 lbs45422 lbs51076 lbs51076 lbs51076 lbs51076 lbs51076 lbs51076 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.05 3.99 4.28 4.30 4.54 4.19 4.19 4.26 4.26 4.19 4.30
Heating Ability
Firebox Area345.50 sq. ft267 sq. ft267 sq. ft267 sq. ft242 sq. ft267 sq. ft242 sq. ft242 sq. ft242 sq. ft242 sq. ft242 sq. ft
Grate Area66.70 sq. ft70.40 sq. ft70.40 sq. ft70.40 sq. ft70.40 sq. ft70.40 sq. ft70.40 sq. ft70.40 sq. ft70.40 sq. ft70.40 sq. ft70 sq. ft
Evaporative Heating Surface3783 sq. ft4253 sq. ft5559 sq. ft4253 sq. ft4215 sq. ft5559 sq. ft4215 sq. ft4215 sq. ft4215 sq. ft4215 sq. ft4216 sq. ft
Superheating Surface882 sq. ft865 sq. ft865 sq. ft890 sq. ft890 sq. ft890 sq. ft890 sq. ft890 sq. ft912 sq. ft
Combined Heating Surface4665 sq. ft5118 sq. ft5559 sq. ft5118 sq. ft5105 sq. ft5559 sq. ft5105 sq. ft5105 sq. ft5105 sq. ft5105 sq. ft5128 sq. ft
Evaporative Heating Surface/Cylinder Volume205.21247.18361.39276.48274.01323.08244.97244.97244.97244.97245.03
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1334014784133761337612672140801408014080140801408014000
Same as above plus superheater percentage1587517297133761565014826140801647416474164741647416520
Same as above but substitute firebox area for grate area8222965602507305935450965534005662856628566285662857112
Power L115320171388090156921493584141639716397163971639716640
Power MT609.93706.06347.29671.09638.72346.64675.53663.90663.90675.53668.82

Photos

Reference

Credits

Introduction and roster provided by Richard Duley. Class details and specifications provided by Steve Llanso of Sweat House Media.