Rock Island 2-8-2 "Mikado" Locomotives

In 1911 the Chicago, Rock Island & Pacific Railway needed higher speed so it designed a new 2-8-2 Locomotive. The Baldwin Locomotive Works delivered 40 (road numbers 2500-2539) of the "Mikados" in 1912 and the American Locomotive Company delivered another 10 (road numbers 2540-2549) in the same year. They were designated as Class K-60.

Another group of 25 Class K-60 "Mikados" was delivered by Baldwin in 1913. This group was assigned road numbers 2550-2574. The specifications were identical to the previous Class K-60 Baldwin-built locomotives. A final group of Class K-60 2-8-2s came from ALCO in 1918. These 20 locomotives were similar to the 1913 "Mikados" and were assigned road numbers 2575-2590.

During World War I the USRA allocated twenty USRA "Mikado-Light" locomotives to the CRI&P. Baldwin built nine of them (road numbers 2300-2308) and ALCO built the other eleven (road numbers 2309-2319). These locomotives were designated as Class K-55 on the CRI&P.

In 1923, Baldwin and ALCO each delivered 24 more of the Class K-60 "Mikados. The Baldwin-built locomotives were given road numbers 2591-2618 and the ALCO group was assigned road numbers 2619-2642.

Later in 1923, another 36 ALCO-built 2-8-2s were Added to the roster. These locomotives were similar to the Class K-60 but had a 210 psi boiler pressure which increased its Tractive effort to 66,640 pounds. They were designated as Class K-60b and were assigned road numbers 2643-2678.

In 1926, the CRI&P bought another 10 "Mikados" from ALCO. These locomotives were similar to the Class K-60b and were designated as Class K-64b and assigned road numbers 2679-2688.

A final group of 2-8-2s were delivered by ALCO in 1927 and were similar to the Class K-64b. They were classified as Class K-67K and were given road numbers 2689-2731.

There are no surviving CRI&P 2-8-2 "Mikado" type locomotives.

Roster by Richard Duley

ClassQty.Road NumbersYear BuiltBuilderNotes
K-60402500 - 25391912Baldwin 
102540 - 25491912ALCO 
252550 - 25741913Baldwin 
202575 - 25941918ALCO 
K-5592300 - 23081919BaldwinUSRA allocated "Mikado-Light" locomotives
112309 - 23191919ALCOUSRA allocated "Mikado-Light" locomotives
K-60242595 - 26181923BaldwinFour of these locomotives were sold to the Soo Line in 1941
242619 - 26421923ALCO 
K-60b362643 - 26781923ALCO 
K-64b102679 - 26881926ALCO 
K-67b252689 - 27131927ALCO 

Class Details by Steve Llanso of Sweat House Media

Class K-55 (Locobase 7231)

Data from RI to 1951Locomotive Diagrams Combined supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

As part of the USRA's distribution of Mikados, Baldwin built the first 9 of the Rock Island's batch of 20 and Alco produced the latter 11. Locobase has several examples of as-built light Mikes, so this entry shows the Rock's firebox reconditioning in which 28 sq ft of arch tubes was replaced by 77 sq ft of thermic syphons.

Class K-60 (Locobase 2796)

The first of the Rock's Mikados, these engines were built in the following batches:

Numbers Builder Date Valve gear

2500-2539 Baldwin 1912 Baker

2540-2549 Alco 1912 Walschaerts

2550-2574 Baldwin 1913 Baker

2575-2594 Alco 1918 Walschaerts

48 more followed after World War I.

Piston valves were of a generous 16" diameter and the engines were delivered with brick arches and 29 sq ft of arch tubes. WJ Tollerton, Chief Mechanical Superintendent said in Railway Age (9 January 1914) that they'd proven to be "excellent steamers; there is experienced no difficulty in maintaining full boiler pressure at all times and the absence of black smoke at the stack is evidence of their boiler efficiency." Per 1000 gross ton miles on the Herington-Pratt, Kansas section (126 miles at a ruling grade of 0.8%), the Mikes dropped coal consumption from 96 lb to 66 lb compared to the earlier 2-8-0s while raising the average train load from 1,650 tons to 2,400 tons.

Tenders held either 16 tons of coal or 3,200 to 4,400 gallons of oil. Boiler pressure in these engines began at 180 psi; the earlier ones were raised to 190 psi and later engines were delivered at 200-210 psi. Many had firebox updates in which the arch tubes were replaced by 82 sq ft of thermic syphons, which increased direct heating surface to 361 sq ft. Some even received roller bearings.

Clearly a prized workhorse that soldiered on to the end of steam on the Rock.

Class K-64 (Locobase 7232)

Data from RI to 1951 Combined Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

The Rock Island continued building after World War I a line of Mikados that it first procured in 1912, but wrought several important changes. Both the direct heating surface and the superheater surface areas were increased, the former being accomplished by including 116.7 sq ft thermic syphons and the later by increasing the number of flues. The postwar class of 48 can be further subdivided by the number of tubes and a consequent difference in evaporative heating surface. The first two batches, which arrived in 1920 and 1922, were as shown in the specs. The last 24 are depicted in Locobase 7233.

Class K-64 (Locobase 7233)

Data from RI to 1951 Combined Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

As the run of Mikados described in Locobases 2796 and 7232 came to its conclusion in 1923, Brooks rang one more change on the boiler. Ten more tubes were deleted in favor of two more superheater flues, which resulted in a still higher percentage of superheater area in relation to overall heating surface. The firebox heating surface remained the same and still included 116.7 sq ft of thermic syphons.

Class K-64B (Locobase 11)

Data from 1930 Locomotive Cyclopedia and RI to 1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Firebox had thermic syphons. One of a series of Mikado classes built for the Rock Island before and after World War I. Boiler pressure was later raised to 215 psi and the class redesignated K-68B to signify the increased tractive effort. A 14,000-gallon tender added later put 237,600 lb on the rails.

Class K-67B (Locobase 7223)

Data from RI to 1951 Diagram Combined Books supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Firebox had 82 sq ft of thermic syphons. These were the last Mikados delivered to the Rock Island and differed from the K-64B from Brooks (Locobase 11) only in steam pressure and having 2 fewer boiler tubes.

Specifications by Steve Llanso of Sweat House Media
Locobase ID7231 2796 7232 7233 11 7223
RailroadRock Island (CRI & P)Rock Island (CRI & P)Rock Island (CRI & P)Rock Island (CRI & P)Rock Island (CRI & P)Rock Island (CRI & P)
Road Numbers2300-23192500-25942595-26182619-26422679-26882689-2713
Valve GearWalschaertBaker or WalschaertBakerBakerBakerBaker
Locomotive Length and Weight
Driver Wheelbase16.75'17'17'17'17'17'
Engine Wheelbase36.08'35.17'35.33'35.33'36.20'36.20'
Ratio of driving wheelbase to overall engine wheebase 0.46 0.48 0.48 0.48 0.47 0.47
Overall Wheelbase (engine & tender)71.37'67.04'72.98'73'73'73'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers216950 lbs238200 lbs249053 lbs246000 lbs257000 lbs263000 lbs
Engine Weight284300 lbs318850 lbs337240 lbs331000 lbs347000 lbs355000 lbs
Tender Light Weight200600 lbs189900 lbs190000 lbs188000 lbs196000 lbs199500 lbs
Total Engine and Tender Weight484900 lbs508750 lbs527240 lbs519000 lbs543000 lbs554500 lbs
Tender Water Capacity10000 gals9000 gals9000 gals10000 gals10000 gals14000 gals
Tender Fuel Capacity (oil/coal)5000 gals16 tons16 tons3600 gals16 tons4550 gals
Minimum weight of rail (calculated) on which locomotive could run90 lb/yard99 lb/yard104 lb/yard103 lb/yard107 lb/yard110 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter63"63"63"63"63"63"
Boiler Pressure200 psi190 psi200 psi200 psi200 psi210 psi
Cylinders (dia x stroke)26" x 30"28" x 30"28" x 30"28" x 30"28" x 30"28" x 30"
Tractive Effort54724 lbs60293 lbs63467 lbs63467 lbs63467 lbs66640 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.96 3.95 3.92 3.88 4.05 3.95
Heating Ability
Firebox Area335 sq. ft259 sq. ft388.70 sq. ft388.70 sq. ft339 sq. ft339 sq. ft
Grate Area66.70 sq. ft63 sq. ft63 sq. ft63 sq. ft63 sq. ft63 sq. ft
Evaporative Heating Surface3697 sq. ft4276 sq. ft3600 sq. ft3443 sq. ft3506 sq. ft3485 sq. ft
Superheating Surface882 sq. ft819 sq. ft900 sq. ft914 sq. ft992 sq. ft1036 sq. ft
Combined Heating Surface4579 sq. ft5095 sq. ft4500 sq. ft4357 sq. ft4498 sq. ft4521 sq. ft
Evaporative Heating Surface/Cylinder Volume200.54200.00168.38161.04163.98163.00
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation133401197012600126001260013230
Same as above plus superheater percentage158751388515120152461537216273
Same as above but substitute firebox area for grate area797305708493288940658271687564
Power L1151621207613401133701387814958
Power MT616.30447.07474.50479.28476.20501.55