Illinois Central 4-6-4 "Hudson" Locomotives of the USA

The Illinois Central rebuilt one of its 2-8-4 "Berkshires" (number 7038) to be a 4-6-4 "Hudson" in its own shops and gave it road number 2499.

When first rebuilt this new "Hudson" had 27 x 30 cylinders, 73.5 drivers, a 270 psi boiler pressure, and a tractive effort of 68,350 pounds. The tractive effort was too great for the weight on the drivers, so this locomotive was very slippery. After extensive tests in 1937, it was decided that the cylinder diameter would be reduced by three inches. After this modification number 2499 was assigned to passenger service.

Class Details by Steve Llanso of Sweat House Media

Class 1/2499 (Locobase 1357)

Data from IC 12 - 1937 Locomotive Diagrams and Illinois Central RR 1 - 1947 Locomotive List supplied in August 2013 by Allen Stanley from his extensive Raildata collection. See also a letter in the November 1997 issue of the "Green Diamond",the Illinois Central Historical Society Magazine as reproduced on, last accessed 15 November 2015, for full details of the origins of this single Hudson. (Many thanks to Chris Hohl for his 29 April 2015 email pointing out the error in valve gear and his 26 November 2015 email and spreadsheet supplying more details and his 2 February 2016 email correcting a typo in the cylinder diameter.)

Perhaps the only freight Hudson built. An unsuccessful rebuild in May 1937 using the Berkshire 7038's boiler (Locobase 48) and placing it on a one-piece cast-steel bed. While the 1947 Locomotive List states that the shops used the 2038's boiler, the data suggest that only the firebox was retained and a new boiler adopting the Type A superheater was built. Moreover, piston valve diameters decreased from 14" to 12" (356 to 305 mm).

According to the Green Diamond article, a freight-drivered 4-6-4 was an attempt to provide "right-sized" power for fast freight trains. The first set of modifications produced a slippery and top-heavy locomotive that was susceptible to derailing. Because the railroad retained the original 27" cylinders, the 1 generated far too much tractive effort for the weight the engine put on much taller drivers. A photograph shows some odd features, including an outside-equalized front truck,

The account says that it fell to John McIntyre, road foreman of engines at Clinton (Ia), to try to solve some of 1's problems. His rebalancing of the equalizing system to reapportion the weight on the drivers seemed to help. Still, as John S Ingles, writing in Drury (1993) observed, the engine was too powerful for its limited adhesion.

Chris Hohl's research suggests that it was in the late 1930s that the Clinton shops fitted new 24 1/2" cylinders to the 1. Its tractive effort dropped to 55,200 lb and its FofA rose to a more manageable 3.8. In 1947, adhesion weight was given as 198,287 lb (89,942 kg).

A review of the 1937 and 1955 diagram books suggests that the IC originally planned to convert the entire class of 2-8-4s, a supposition prompted by the presentation of the Hudson data on 1937 diagrams showing all 50 engines as converted.

After the 1 revealed how slippery three-axle adhesion could be, it seems that the railroad used the new boiler in its 1939 Berkshire rebuild; see Locobase 15624.

The Green Diamond letter described some of the 1's duties after the 1939 modifications: "From Cimic to Clinton, No. 1 was rated at 4,600 tons while the 2500 series 4-8-2's were rated al 6000 tons. No.1 handled coal trains as well as dispatch trains from Clinton to Markham." It never returned to the Springfield Division.

The IC changed the 1's number to 2499 in July 1945.

he IC also renumbered the 1 to 2499. It was retired in 1950.

Specifications by Steve Llanso of Sweat House Media
Locobase ID1357
RailroadIllinois Central (IC)
Number in Class1
Road Numbers1/2499
Number Built
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)12.75
Engine Wheelbase (ft)39.71
Ratio of driving wheelbase to overall engine wheebase 0.32
Overall Wheelbase (engine & tender) (ft)82.29
Axle Loading (Maximum Weight per Axle) (lbs)70,000
Weight on Drivers (lbs)209,918
Engine Weight (lbs)398,126
Tender Light Weight (lbs)286,000
Total Engine and Tender Weight (lbs)684,126
Tender Water Capacity (gals)15,000
Tender Fuel Capacity (oil/coal) (gals/tons)20
Minimum weight of rail (calculated) (lb/yd)117
Geometry Relating to Tractive Effort
Driver Diameter (in)73.50
Boiler Pressure (psi)265
High Pressure Cylinders (dia x stroke) (in)27" x 30"
Tractive Effort (lbs)67,023
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.13
Heating Ability
Firebox Area (sq ft)414
Grate Area (sq ft)100
Evaporative Heating Surface (sq ft)4773
Superheating Surface (sq ft)1355
Combined Heating Surface (sq ft)6128
Evaporative Heating Surface/Cylinder Volume240.09
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation26,500
Same as above plus superheater percentage32,330
Same as above but substitute firebox area for grate area133,846
Power L131,087
Power MT979.45



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