The WP purchased thirty-six "Mikados", from the American Locomotive Company, all of the same basic design. These locomotives arrived on the WP in seven small groups beginning with five in 1918, continuing with five more in 1919, five in 1921, six in 1923, five in 1924, five in 1926 with the last five arriving in 1929. They were designated as Class MK-60 and assigned road numbers 301 through 332. The Class MK-60 locomotives had 63" diameter drivers, 28" x 30" cylinders, a 190 psi boiler pressure and they exerted 60,300 pounds of tractive effort.
In addition to the thirty-six ALCO built 2-8-2s there was five Baldwin built 2-8-2s added to the roster in 1918. These locomotives were USRA allocated Makado-Lights and were designated as Class MK-55 and given road numbers 321 through 325. The WP sold these five locomotives to the Wabash in 1920 and assigned numbers 321 through 325 to the MK-60s bought in 1923 and 1924.
There is one surviving Western Pacific 2-8-2 "Mikado" type locomotives. It is road number 334 and it is currently in storage at the Western Railway Museum in Vista Junction, CA.
|Class||Road Class||Qty.||Road Numbers||Year Built||Builder||Notes|
Data from WP 2 - 1946, WP 3 1949, and WP 2 -1950 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. , accessed 4 July 2006 is Frank Brehm's detailed review of this class's origins and fate. The first 5 Mikes on the WP (works# 59995-59999) had about the same proportions as the USRA Heavy design of the same year, but slight differences in cylinder volume and grate area. All of them had 16" piston valves. The unit price on delivery was $63,740. Other members of the class would come a few years later; they're shown in Locobase 7629. Other members of the class would come a few years later; they're shown in Locobase 7629. Sometime later the WP increased direct heating surface in all their Mikados from 318 sq ft to 380 sq ft by replacing 30 sq ft of arch tubes with 92 sq ft of thermic syphons. Despite a 10-psi increase in working boiler pressure, the class was still classed as MK-60s and rated at 60,400 lb tractive effort. Of this pioneer quintet, 304 was the first to leave service (November 1947) and 303 the last (April 1952).
Data from WP 2 - 1946, WP 3 1949, and WP 2 -1950 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. , accessed 4 July 2006 is Frank Brehm's detailed review of this class's origins and fate. Three years after Brooks delivered the 5 Mikes shown in Locobase 7628, the railroad returned for 5 more (works# 63014-63018). Differences were slight: a slight decrease in firebox heating surface and an 2 1/2-ton increase in adhesion weight. One other change: the unit price on delivery was now $74,280. In 1923, prices had plummeted. The next 6 in this class (works# 64259-64264) were priced at $54,929 each. The engines were otherwise identical, but the tenders now held 10,000 gallons of water and 4,000 gallons of fuel oil. Sometime later the WP increased direct heating surface in these Mikados from 314 sq ft to 376 sq ft by replacing 30 sq ft of arch tubes with 92 sq ft of thermic syphons. Despite a 10-psi increase in working boiler pressure, the class was still classed as MK-60s and rated at 60,400 lb tractive effort. 314 was the first to leave service (February 1949) and 323 the last (March 1952).
Data from Locomotive Cyclopedia 1930 and from WP 2 - 1946, WP 3 1949, and WP 2 -1950 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error .)This was a continuation of the basic Brooks design for the WP that had started with the 301s (Locobase 7828) and been supplemented by the 311-321 contingent (Locobase 7829). Trading 8 small tubes for 2 flues allowed a substantial increase in superheater area and these were the first WP Mikes to be delivered with 92 sq ft of thermic syphons that, together with 15 sq ft of arch tubes, added considerably to the direct heating surface. The boiler had an Elesco feedwater heater, and a Delta trailing truck booster added 11,000 lb to starting tractive effort. Despite a later 10-psi increase in working boiler pressure, the class was still classed as MK-60s and rated at 60,400 lb tractive effort.  , accessed 4 July 2006 is Frank Brehm's detailed review of this class's origins and fate. Five (65480-65484) were delivered in 1924 and cost $67,699 apiece. 1926 saw 5 more (66741-66745) arrive for a price of $77,640 each. The class closed out with 5 more (67970-67974) costing $79,176 each produced in 1929. Not including the premature withdrawal of 325 in November 1937 (most likely because of accident or component failure), 333 was the first to retire in February 1949 while 329 closed out the class's service in June 1953.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Class||MK-60 - 301||MK-60 - 311||MK-60-71|
|Railroad||Western Pacific (WP)||Western Pacific (WP)||Western Pacific (WP)|
|Number in Class||5||11||15|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||16.50 / 5.03||16.50 / 5.03||16.50 / 5.03|
|Engine Wheelbase (ft / m)||35.92 / 10.95||35.92 / 10.95||36.20 / 11.03|
|Ratio of driving wheelbase to overall engine wheebase||0.46||0.46||0.46|
|Overall Wheelbase (engine & tender) (ft / m)||73.08 / 22.27||73.15 / 22.30||73.21 / 22.31|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||60,375 / 27,386||61,500 / 27,896||61,875 / 28,066|
|Weight on Drivers (lbs / kg)||241,500 / 109,543||246,000 / 111,584||247,500 / 112,264|
|Engine Weight (lbs / kg)||316,000 / 143,335||323,000 / 146,511||330,000 / 149,686|
|Tender Loaded Weight (lbs / kg)||213,900 / 97,024||213,900 / 97,024||264,000 / 119,749|
|Total Engine and Tender Weight (lbs / kg)||529,900 / 240,359||536,900 / 243,535||594,000 / 269,435|
|Tender Water Capacity (gals / ML)||12,140 / 45.98||12,180 / 46.14||15,000 / 56.82|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||21.50 / 19.50||19.50 / 17.70||4000 / 15.20|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||101 / 50.50||103 / 51.50||103 / 51.50|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||63 / 1600||63 / 1600||63 / 1600|
|Boiler Pressure (psi / kPa)||190 / 13.10||200 / 13.80||200 / 13.80|
|High Pressure Cylinders (dia x stroke) (in / mm)||28" x 30" / 711x762||28" x 30" / 711x762||28" x 30" / 711x762|
|Tractive Effort (lbs / kg)||60,293 / 27348.48||63,467 / 28788.18||63,467 / 28788.18|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.01||3.88||3.90|
|Firebox Area (sq ft / m2)||380 / 35.32||376 / 34.94||391 / 36.33|
|Grate Area (sq ft / m2)||70.30 / 6.53||70.30 / 6.53||70.30 / 6.53|
|Evaporative Heating Surface (sq ft / m2)||3818 / 354.83||3814 / 354.46||3798 / 352.97|
|Superheating Surface (sq ft / m2)||857 / 79.65||857 / 79.65||973 / 90.43|
|Combined Heating Surface (sq ft / m2)||4675 / 434.48||4671 / 434.11||4771 / 443.40|
|Evaporative Heating Surface/Cylinder Volume||178.58||178.39||177.64|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||13,357||14,060||14,060|
|Same as above plus superheater percentage||15,761||16,591||16,872|
|Same as above but substitute firebox area for grate area||85,196||88,736||93,840|