Illinois Central 4-8-0 "Mastodon" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 640 (Locobase 190)

Data from the Catalogue Descriptive of Simple and Compound Locomotives built by Brooks Locomotive Works, Dunkirk, NY (Buffalo, NY: Matthew-Northrup Company, 1899), which claimed it as the "heaviest freight locomotive in the world." (doubtless a short-lived distinction). See also "12-Wheel Freight Locomotive, Illinois Central Railroad", American Engineer and Railroad Journal, Volume 73, No 10 (October 1899), pp. 315-318; and "The Largest Locomotive in the World," Engineering News, Volume XLII, No 17 (26 October 1899), pp. 266-267; and W O Moody, Mechanical Engineer, "ICRR's Largest Locomotive, 1899 and 1920", Illinois Central Magazine, Volume 9, No 3 (September 1920), pp. 41-42; and Peoria & Pekin Union 1925 Locomotive Diagrams supplied in August 2013 by Allen Stanley from his extensive Raildata collection. Works number was 3298 in August 1899.

Brooks builder info from B.Rumary, 25 Kingscombe, Gurney Slade, Radstock, BA3 4TH, ENGLAND and Jeremy Lambert as supplied by Allen Stanley in March 2004. Works #3298 in August 1899.

Specifications had included the power to pull a 2,045-ton train up a .75% grade, combined with 3% curves, at 15 mph. Further construction details: "The boiler is of the Player-Belpaire type, and the thickness of the plate 15/16" and 1", is, we believe, the greatest ever used upon (sic) locomotive boilers. The diameter at front end is 82", connection 88", and throat 91 1/4."

"Nearly all parts of this locomotive usually made of cast iron are, with the exception of the cylinders, made of cast of pressed steel or malleable iron."

The cylinders were fed through piston valves, a relatively rare combination at the time; diameter of each valve was 12" (305 mm) and its stroke was a relatively long seven inches (178 mm). The AERJ report explained that piston valves were "specially desirable" to cope with the large cylinders and high (210 psi) boiler pressure. The report estimated each valve's weight as around 200 lb (90.7 kg) and added "a slide valve would be much heavier for steam ports 28 inches long."

WO Moody's 1920 article comparing this 4-8-0 with the 2901 class of 2-10-2s noted that the 640's arrival represented an 89% increase in tractive effort over the IC's Consolidations.

Whatever its merits, 640 remained an "only". After a couple of decades with the IC, it was sold to the Peoria & Pekin Union as their #42 in June 1917. By then the tender carried 15 tons of coal and weighed 147,600 lb (66,950 kg). The engine's adhesive weight now came to 181,400 lb (82,282 kg) and its overall weight rose to 221,450 lb (100,448 kg). Boiler pressure was slightly reduced to 200 psi (13.8 bar).

scrapped in the middle 1920s.

Specifications by Steve Llanso of Sweat House Media
Locobase ID190
RailroadIllinois Central (IC)
Number in Class1
Road Numbers640
Number Built1
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft)15.75
Engine Wheelbase (ft)26.50
Ratio of driving wheelbase to overall engine wheebase 0.59
Overall Wheelbase (engine & tender) (ft)55.17
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)193,200
Engine Weight (lbs)232,000
Tender Loaded Weight (lbs)132,700
Total Engine and Tender Weight (lbs)364,700
Tender Water Capacity (gals)7000
Tender Fuel Capacity (oil/coal) (gals/tons)12
Minimum weight of rail (calculated) (lb/yd)81
Geometry Relating to Tractive Effort
Driver Diameter (in)57
Boiler Pressure (psi)210
High Pressure Cylinders (dia x stroke) (in)23" x 30"
Tractive Effort (lbs)49,698
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.89
Heating Ability
Firebox Area (sq ft)263
Grate Area (sq ft)37.50
Evaporative Heating Surface (sq ft)3500
Superheating Surface (sq ft)
Combined Heating Surface (sq ft)3500
Evaporative Heating Surface/Cylinder Volume242.61
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7875
Same as above plus superheater percentage7875
Same as above but substitute firebox area for grate area55,230
Power L16659
Power MT303.95


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