Western Pacific 2-8-2 "Mikado" Type Locomotives

Introduction

The Western Pacific Railroad's main line connected San Francisco, CA with Salt Lake City, Utah. The railroad did not originally have any branches and in 1915 it went into bankruptcy. It was reorganized and soon after began to acquire short line railroads and secured a connection with the Northern Pacific.

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.

Roster by Richard Duley

ClassRoad ClassQty.Road NumbersYear BuiltBuilderNotes
MK-603015301-3051918ALCO1
MK-555321-3251919Baldwin2
MK-603065306-3101919ALCO3
MK-603115311-3151921ALCO4
MK-603166316-3211923ALCO5
MK-603225322-3261924ALCO6
MK-603275327-3311926ALCO7
MK-603325332-3361929ALCO8
Notes:
  1. Numbers 304 and 305 scrapped in 1950. Number 302 scrapped in 1951. Numbers 301 and 303 scrapped in 1953.
  2. These locomotives allocated by USRA. They were USRA Mikado-Light and were given road numbers 321-325 in order to save room for more Class MK-60 locomotives. The WP sold these five locomotives to the Wabash in 1920.
  3. Numbers 306-310 bought from Elgin, Joliet & Eastern in 1920. Numbers 306, 307 and 310 scrapped in 1952. Numbers 308 and 309 scrapped in 1953.
  4. Numbers 311-315 scrapped in 1950.
  5. Number 316 scrapped in 1951. Numbers 317-321 scrapped in 1952.
  6. Numbers 322-332 had Delta trailing truck boosters, which increased the tractive effort by 11,000 pounds. Number 325 scrapped in 1939. Numbers 322 and 324 scrapped in 1950. Numbers 323 and 326 scrapped in 1953.
  7. Number 327 scrapped in 1950. Number 330 scrapped in 1952. Numbers 328, 329, 331 scrapped in 1953.
  8. Numbers 332, 333, 335 scrapped in 1950. Number 336 scrapped in 1953. Number 334 was saved and it is currently in storage at the Western Railway Museum in Vista Junction, CA.

Class Details by Steve Llanso

Class MK-60 - 301 (Locobase 7628)

Data from WP 2 - 1946, WP 3 1949, and WP 2 -1950 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

http://www.wplives.com/motivepower/srosters/Class_301_Roster__/class_301_roster__.html , 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).

Class MK-60 - 311 (Locobase 7629)

Data from WP 2 - 1946, WP 3 1949, and WP 2 -1950 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

http://www.wplives.com/motivepower/srosters/Class_311_Roster__/class_311_roster__.html , 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).

Class MK-60-71 (Locobase 43)

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 collection.

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.

http://www.wplives.com/motivepower/srosters/Class_322_Roster__/class_322_roster__.html , 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.


Specifications by Steve Llanso
ClassMK-60 - 301MK-60 - 311MK-60-71
Locobase ID7628 7629 43
RailroadWestern Pacific (WP)Western Pacific (WP)Western Pacific (WP)
CountryUSAUSAUSA
Whyte2-8-22-8-22-8-2
Road Numbers301-305311-321322-336
GaugeStdStdStd
BuilderAlco-BrooksAlco-BrooksAlco
Year191819211926
Valve GearWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase16.50'16.50'16.50'
Engine Wheelbase35.92'35.92'36.20'
Ratio of driving wheelbase to overall engine wheebase 0.46 0.46 0.46
Overall Wheelbase (engine & tender)73.08'73.15'73.21'
Axle Loading (Maximum Weight per Axle)60375 lbs61500 lbs61875 lbs
Weight on Drivers241500 lbs246000 lbs247500 lbs
Engine Weight316000 lbs323000 lbs330000 lbs
Tender Light Weight213900 lbs213900 lbs264000 lbs
Total Engine and Tender Weight529900 lbs536900 lbs594000 lbs
Tender Water Capacity12140 gals12180 gals15000 gals
Tender Fuel Capacity (oil/coal)21.5 tons19.5 tons4000 gals
Minimum weight of rail (calculated) on which locomotive could run101 lb/yard103 lb/yard103 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter63"63"63"
Boiler Pressure190 psi200 psi200 psi
Cylinders (dia x stroke)28" x 30"28" x 30"28" x 30"
Tractive Effort60293 lbs63467 lbs63467 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.01 3.88 3.90
Heating Ability
Firebox Area380 sq. ft376 sq. ft391 sq. ft
Grate Area70.30 sq. ft70.30 sq. ft70.30 sq. ft
Evaporative Heating Surface3818 sq. ft3814 sq. ft3798 sq. ft
Superheating Surface857 sq. ft857 sq. ft973 sq. ft
Combined Heating Surface4675 sq. ft4671 sq. ft4771 sq. ft
Evaporative Heating Surface/Cylinder Volume178.58178.39177.64
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation133571406014060
Same as above plus superheater percentage157611659116872
Same as above but substitute firebox area for grate area851968873693840
Power L1125331316914252
Power MT457.65472.08507.80

Photos

Reference

Credits

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