The first "Mikado" type locomotives on the GM&N were eight that were conveyed from the NOM&C. They were built by the Baldwin Locomotive Works in 1912 and carried road numbers 101 through 108. These locomotives were very light compared to most 2-8-2s built. They weighed 196,000 pounds which was about 68% of the USRA allocated "Mikado-Light" locomotive weight of 290,000 pounds. The locomotives had 57" diameter drivers, 22" x 28" cylinders, a 190 psi boiler pressure and they exerted 38,397 pounds of tractive effort.
After WW I, the GM&N was in need of new locomotives and it ordered four new "Mikados" from Baldwin. They were delivered in 1920 and were given road numbers 109 through 112. These locomotives were close copies of the "Mikados" already on the roster. They were 9,800 pounds heavier, the boiler pressure was 200 psi and they exerted 40,818 pounds of tractive effort. The evaporative heating surface was 2575 square feet and with the superheater the combined heating surface was 3,125 square feet.
There are no surviving GM&N 2-8-2 "Mikado" type locomotives.
|Qty.||Road Numbers||Year Built||Builder||Notes|
Like the Pacifics supplied to the NOM & C at the same time (Locobase 2789), the eight Mikados of 1912 were built with 13" piston valves supplying an identical cylinder volume and actuated through outside radial valve gear. Smaller drivers suited their freight-hauling role and their boilers had 3 fewer tubes for some reason. For mainline Mikados of the time, these were relatively small, lightweight engines.
The class adopted the herald of the Gulf, Mobile & Northern in 1917, but kept their numbers.
GM & N sold the 101-104 to the Tennessee, Alabama & Gulf, which added 100 to each road number and operated 201-204. The TAG sold all 4 in 1937 to locomotive rebuilder/reseller Southern Iron & Equipment. The Sydney & Louisburg of Cape Breton in Nova Scotia, Canada, bought the quartet in 1938 and renumbered them 73, 75, 76, 74, respectively. They ended their days in 1957.
The latter 4 remained on the GM & N even after it was merged with the Mobile & Ohio and they kept their road numbers. All were scrapped by 1948.
Relatively small Mikados purchased just after the return of railroading to private ownership. The cylinders were supplied by relatively large 13" (330 mm) piston valves. Rail weight was 70 lb/yard (35 kg/metre) and the profile was very mild as it featured 1% maximum grades and 4 degrees curvature
All moved over to the Gulf, Mobile & Ohio roster while retaining their road numbers. Locobase noted a 30-sq ft increase in direct heating surface area after 1924 and suspects that arch tubes may have been added to the firebox.
Three were scrapped in the late 1940s, while 111 was sold overseas.
Apparently encountering some of the Southern's myriad K-class Mikados (Locobase 44) induced the M & O to order four duplicates in 1911.
Later orders increased the count to 21 locomotives. The last three used Southern valve gear in place of the Walschaert design.
This was a class that served the M & O and its successor Gulf, Mobile & Ohio to the end of steam.
Several years after the Light Mikados designed by the United States Railroad Administration had proliferated throughout the mainline rail network, individual railroads were still ordering slight variations of this very successful locomotive. The M&O's quintet duplicated nearly every dimension and, like the light Mikes, their firebox heating surface areas included 50 sq ft (4.7 sq m) in the combustion chamber and 27 sq ft (2.5 sq m) in arch tubes. Cylinders were served by piston valves measuring 14" (356 mm) in diameter.
The one significant difference was the use of Baker gear instead of the original Walschaert valve gear. Appliances varied; for example, the Franklin power shaker (of the grate) was expressly omitted.
All served the M&O and successor GM&O into the late 1940s.
|Specifications by Steve Llanso of Sweat House Media|
|Railroad||New Orleans, Mobile & Chicago (GM&O)||Gulf, Mobile & Northern (GM&O)||Mobile & Ohio (GM&O)||Mobile & Ohio (GM&O)|
|Number in Class||8||4||21||5|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||15 / 4.57||15 / 4.57||16.50 / 5.03||16.75 / 5.11|
|Engine Wheelbase (ft / m)||31.67 / 9.65||31.67 / 9.65||34.75 / 10.59||36.08 / 11|
|Ratio of driving wheelbase to overall engine wheebase||0.47||0.47||0.47||0.46|
|Overall Wheelbase (engine & tender) (ft / m)||62.46 / 19.04||62.62||67.06 / 20.44||71.37 / 21.75|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||40,200 / 18,234|
|Weight on Drivers (lbs / kg)||150,000 / 68,039||160,800 / 72,938||212,300 / 96,298||220,000 / 99,790|
|Engine Weight (lbs / kg)||191,000 / 86,636||205,800 / 93,349||269,000 / 122,016||292,000 / 132,449|
|Tender Loaded Weight (lbs / kg)||115,000 / 52,163||138,000 / 62,596||153,000 / 69,400||185,400 / 84,096|
|Total Engine and Tender Weight (lbs / kg)||306,000 / 138,799||343,800 / 155,945||422,000 / 191,416||477,400 / 216,545|
|Tender Water Capacity (gals / ML)||6000 / 22.73||6000 / 22.73||8000 / 30.30||10,000 / 37.88|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||14 / 12.70||14 / 12.70||12 / 10.90||16 / 14.50|
|Minimum weight of rail (calculated) (lb/yd)||63||67||88||92|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||57 / 1448||57 / 1448||63 / 1600||63 / 1600|
|Boiler Pressure (psi / kPa)||185 / 12.80||200 / 13.80||175 / 12.10||200 / 13.80|
|High Pressure Cylinders (dia x stroke) (in / mm)||22" x 28" / 559x711||22" x 28" / 559x711||27" x 30" / 686x762||26" x 30" / 660x762|
|Tractive Effort (lbs / kg)||37,387 / 16958.48||40,418 / 18333.32||51,638 / 23422.63||54,724 / 24822.42|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.01||3.98||4.11||4.02|
|Firebox Area (sq ft / m2)||180 / 16.72||162 / 17.52||212 / 17.74||283 / 26.29|
|Grate Area (sq ft / m2)||46.80 / 4.35||46.80 / 4.35||53.30 / 4.95||66.70 / 6.20|
|Evaporative Heating Surface (sq ft / m2)||2565 / 238.29||2565 / 238.38||3231 / 297.10||3780 / 351.17|
|Superheating Surface (sq ft / m2)||550 / 51.10||550 / 51.12||699 / 64.94||882 / 81.94|
|Combined Heating Surface (sq ft / m2)||3115 / 289.39||3115 / 289.50||3930 / 362.04||4662 / 433.11|
|Evaporative Heating Surface/Cylinder Volume||208.21||208.21||162.52||205.04|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||8658||9360||9328||13,340|
|Same as above plus superheater percentage||10,216||11,045||11,006||15,875|
|Same as above but substitute firebox area for grate area||39,294||38,232||43,778||67,354|