Central of Georgia 4-8-2 "Mountain" Locomotives in the USA

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The Central of Georgia Railroad bought its first ten "Mountain" type locomotives from the American Locomotive Company. They were delivered in 1919 and 1920. These ten locomotives were designated Class MT and assigned road numbers 1681 through 1690 (later changed to numbers 481 through 490). They had 27 x 28 cylinders, 69" drivers, a boiler pressure of 200 psi, a weight of 316,000 lbs, and a tractive effort of 50,000 pounds. Later the boiler pressure was raised to 210 psi increasing the tractive effort to 52,900 pounds.

Between 1922 and 1925, seventeen more Class MT "Mountain" type locomotives were received from ALCO. They were numbered 1671 through 1680 (later changed to 471 through 480) and 1691 through 1697 (later changed to 491 through 497).

The last five Class MT 4-8-2s were delivered from the Baldwin Locomotive Works in 1926. These were numbered 466 through 470 and were very similar to the "Mountains" built by ALCO.

All Class MT "Mountains" had 27" dia. x 28" stroke cylinders, 69" drivers and with a 210 psi boiler pressure exerted 52,920 lbs of tractive effort.

Class Details by Steve Llanso of Sweat House Media

Class MT (Locobase 3103)

Data from CofG 4 -1927 and CofG 6 -1947 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also Volume 75, pp. 349+. (Thanks to Chris Hohl for the valve gear ID and for his 29 Novmeber 2015 email noting the original 190 psi setting for the boiler.) The first 27 were delivered over a six-year period by Alco's Richmond works. Works numbers were

1919 58035-58037 (road #481-483)

1920 62384-62387 (484-487), 62417-62419 (488-490),

1922 63531-63532 (491-492),

1923 64584-64588 (493-497), 65265-65269 (476-480).

1925 66322-66326 (471-475).

1926 Baldwin works numbers were 58997-58998 in January, 59059-59061 in March.

Total engine weight ranged from 316,000 lb to 326,500 lb. The class was delivered with a stated superheater area of 900 sq ft (83.6 sq m) and boilers set to 190 psi (13.1 bar). It wasn't too long before the Central changed the boiler's layout from its original arrangement of 198 2 1/4" tubes and added 61 sq ft (5.65 sq m) of syphons to the firebox heating surface. In fact, the last batch of Baldwins were delivered with syphons. Several of the engines had had their pressure settings raised to 200 psi by 1932 and by 1947, boilers on the entire class were set to 210 psi as shown in the specs.

Somehow the superheater later gained 64 sq (5.95 sq m) ft of heating surface without changing the number, diameter, or length of flues. The increase might have represented a recalculation rather than any actual changes.

These Mountains ran the CofGa mainlines pulling trains from the Midwest to Florida. Retirements began in 1948 and ended in 1953.

Specifications by Steve Llanso of Sweat House Media
Locobase ID3103
RailroadCentral of Georgia (CofGa)
Number in Class32
Road Numbers1671-1697/466-470, 471-497
Number Built32
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)18 / 5.49
Engine Wheelbase (ft / m)38.92 / 11.86
Ratio of driving wheelbase to overall engine wheebase 0.46
Overall Wheelbase (engine & tender) (ft / m)86.08 / 26.24
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)218,200 / 98,974
Engine Weight (lbs / kg)319,100 / 144,741
Tender Loaded Weight (lbs / kg)189,700 / 84,323
Total Engine and Tender Weight (lbs / kg)508,800 / 229,064
Tender Water Capacity (gals / ML)9500 / 34.09
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)15 / 13.60
Minimum weight of rail (calculated) (lb/yd / kg/m)91 / 45.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 1753
Boiler Pressure (psi / kPa)210 / 14.50
High Pressure Cylinders (dia x stroke) (in / mm)27" x 28" / 686x711
Tractive Effort (lbs / kg)52,805 / 23951.97
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.13
Heating Ability
Firebox Area (sq ft / m2)348 / 32.34
Grate Area (sq ft / m2)66.70 / 6.20
Evaporative Heating Surface (sq ft / m2)3702 / 344.05
Superheating Surface (sq ft / m2)967 / 89.87
Combined Heating Surface (sq ft / m2)4669 / 433.92
Evaporative Heating Surface/Cylinder Volume199.51
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation14,007
Same as above plus superheater percentage16,948
Same as above but substitute firebox area for grate area88,427
Power L118,410
Power MT744.03