Raritan River 2-8-2 "Mikado" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 9 (Locobase 12846)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volume 51, p. 365. See also "Mikado Type Locomotives for the Raritan River Railroad ...", Railway and Locomotive Engineering, Volume 29, No 5 (May 1916), p. 164. Works numbers were 42734-42735 in December 1915, 42984 in February 1916, 43058-43059 in March.

R&LE pointed out that although this quintet of light Mikados mustered the same tractive effort as the earlier Consolidations (Locobase 12845), they presented 34% more grate area and 48% more heating surface area. The accompanying photograph shows them to be slim, well-proportioned engines capabale of running on 60 lb/yard (30 kg/metre) rail found on the branch lines and spurs, although the Raritan used 80 lb (40 kg) rail on its 12.3 mile (19.8 km) main line. Moreover, adding a trailing truck enhanced the Mikados' usefulness in the backing and switching that made up a significant part of their operation.

11 suffered a wreck when it collided with an out-of-control string of eight tank cars coming down a hill near South Amboy.

Except for the 12, which was scrapped in 1938, they provided the biggest freight muscle on the RRRR throughout World War II. 11 went to the ferro-knacker in December 1947, 9 in March 1948 and 10 in July. 14 held on the longest, serving more than 35 years before it was scrapped in September 1953.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID12,846
RailroadRaritan River
Number in Class5
Road Numbers9-12, 14
Number Built5
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.67 / 4.17
Engine Wheelbase (ft / m)29 / 8.84
Ratio of driving wheelbase to overall engine wheebase 0.47
Overall Wheelbase (engine & tender) (ft / m)60.96 / 18.58
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)128,000 / 58,060
Engine Weight (lbs / kg)167,000 / 75,750
Tender Loaded Weight (lbs / kg)130,000 / 58,967
Total Engine and Tender Weight (lbs / kg)297,000 / 134,717
Tender Water Capacity (gals / ML)7000 / 26.52
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.90
Minimum weight of rail (calculated) (lb/yd / kg/m)53 / 26.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)51 / 1295
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)20" x 24" / 508x610
Tractive Effort (lbs / kg)32,000 / 14514.97
Factor of Adhesion (Weight on Drivers/Tractive Effort)4
Heating Ability
Firebox Area (sq ft / m2)149 / 13.85
Grate Area (sq ft / m2)44.20 / 4.11
Evaporative Heating Surface (sq ft / m2)2895 / 269.05
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2895 / 269.05
Evaporative Heating Surface/Cylinder Volume331.74
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation8840
Same as above plus superheater percentage8840
Same as above but substitute firebox area for grate area29,800
Power L17091
Power MT488.53

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