Illinois Central 4-8-2 "Mountain" Locomotives in the USA

Class 2300 (Locobase 16032)

Data from IC 1955 Locomotive Diagrams supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange. (Many thanks to Chris Hohl for his 18 March 2015 email noting the need for an entry covering these updated Mountains and his Excel spreadsheet supplying the data.)

Chris Hohl's data included his compilation of the 2400-series 4-8-2s (Locobase 1356 and 6702) that the big, modern (1927) Paducah, Ky shops rebuilt during World War Two.

Hohl's summary shows the following pairings:

2428 > 2300; 2456>2301; 2437>2302; 2413>2303; 2404>2304; 2430>2305; 2406>#2306; 2455>2307

Seeking a substantial boost in power, the railroad's turned out in March 1944 higher-pressure boilers and equipped them with 62 sq ft (5.75 sq m) of circulators in the firebox and 18.5 sq ft (1.7 sq m) in a single thermic syphon in the combustion chamber. (Neither Hohl nor Locobase could determine if all of the 2300s had syphons.)

Once modified, these engines and the 2350s shown in Locobase 16033 had the highest tractive efforts of any two-cylinder 4-8-2s.

Sometime after the end of World War Two, the 2300s had their boiler pressure setting dropped to 260 psi. All of the 2300s were scrapped in February 1960.

Class 2350 (Locobase 16033)

Data from IC 1955 Locomotive Diagrams supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange. (Many thanks to Chris Hohl for his 18 March 2015 email noting the need for an entry covering these updated Mountains and his Excel spreadsheet supplying the data.)

Chris Hohl's data included his compilation of the 2400-series 4-8-2s (Locobase 1356 and 6702) that the IC rebuilt during World War Two. Hohl's summary shows the following pairings:

2415>2350; 2444>2351; 2420>2352

Apparently seeking all the tractive power they could generate on an existing Mountain chassis, the IC's shops at Paducah turned out three more conversions of existing 2400-class 4-8-2s in July 1945. Other than the higher pressure setting, the boiler had the same characteristics including 62 sq ft (5.75 sq m) of circulators in the firebox.

2350-2351 were scrapped in October 1956 and the 2352 in January 1957.

Class 2400 (Locobase 1356)

Data from IC 9 -1928 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Chris Hohl for his 11 November 2012 email correcting builder attribution and road number series.) Works numbers were 64569-64583 in 1923.

This was the IC's first batch of Mountains and the firebox heating surface included 48.3 sq ft (4.5. sq m) of arch tubes. The subsequent batches -- see Locobase 6702 -- introduced thermic syphons into the firebox.

Class 2415 (Locobase 6702)

Data from IC 9 -1928 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Chris Hohl for his 11 November 2012 email correcting builder attribution and road number series and for pointing out the boiler pressure change.) Lima works numbers were 6884-6909 in 1925 and Schenectady works numbers were 67039-67058 in 1926

The first fifteen locomotives in the IC's 4-8-2 fleet are described in Locobase 1356. The current record shows the later batches of Mountain. The biggest difference came in the firebox heating surface where the arch tubes were replaced by 115.5 sq ft from three thermic syphons.

As shown in Locobase's specs, the original boiler pressure setting was 200 psi. 1955 diagrams showed a variety of higher pressures as well as differences in supplemental firebox heating suface area. To summarize, boiler pressures would be set at 230 (15.86 bar) or 245 psi (16.9 bar), generating tractive efforts of 61,824 lb (28,043 kg/275.0 kN) and 65,856 lb (29,872 kg/292.94 kN) and showing factors of adhesion of 4.12 and 3.87, respectively.

Some engines gave up one of the syphons, settling for 79 sq ft (7.34 sq m), plus 8.6 sq ft (0.80 sq m) in one arch tube; total evaporative heating surface added up to 4,682 sq ft (434.72 sq m). Others surrendered all three syphons in favor of 62 sq ft of circulators (5.76 sq m), resulting in 4,654 sq ft (432.37 sq m) of EHS.

Later on, 2418 was the only engine in the class to be fitted with roller bearings.

Class 2500 (Locobase 6703)

Data from IC 12 - 1937 and 1955 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Chris Hohl for his 5 August 2018 email noting the change in boiler pressure and some tender capacities.)

Homebuilt Mountains, this class kept the square diameter x stroke dimensions of the earlier 2400s (Locobase 1356, 6702), but increased the size. The specs refer to the version that had two arch tubes (23.5 sq ft/2.18 sq m) and four thermic syphons (108.5 sq ft/10.08 sq m). Together the two types of appurtenances contributed 132 sq ft (12.25 sq m) to the firebox heating surface.

The IC took a different path in its development of motive power by rebuilding many of its locomotives. This class is a good case in point. The boilers came from the Lima-built 2900 class of 2-10-2s. Beginning in the mid-1930s, IC Paducah shops took the 2900 boilers, reinforced them, and laid them on a new frame. This engine bed comprised a single casting that included the cylinders and the air-pump reservoir. Chris Hohl points out that only one of the class used roller bearings; the 2540 rolled on Timken roller bearings..

One by one, beginning in March 1937, 55 of this class were delivered over the next five years. Only the first engine was fitted with the Standard BK stoker; the others all moved their coal through the Duplex stoker. Originally pressed to 225 psi (15.5 bar), the class's boiler pressure was later reset to 240 psi as shown.

The 1937 diagrams shows the cylinders fittted with 12" (305 mm) piston valves; the 1955 diagrams show 14" (356 mm) piston valves. No other IC locomotives in the earlier book show 12" valves.

Chris Hohl also points out that 17 of the class originally used tenders carrying 16 tons (14.5 metric tons) of coal and 12,000 US gallons of water (45,420 litres); loaded weight was given as 208,600 lb (94,619 kg) . 20 more had larger tenders with a 20 ton (18.1 metric tons/15,000 gallon (56,775 litre) capacity. Still later, the IC adopted auxiliary water cars, at which point all of the class trailed 24 ton/11,000 gallon tenders as shown in the specifications..

After the rebuilds came the 20 locomotives of the 2600 class (see Locobase 3156), which continued the same design, but were newly built.

Class 2600 (Locobase 3156)

Data from IC 1955 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. The specs show the variant that had Type HA superheaters (which had larger-diameter superheater elements). See Tom Morrison, The American Steam Locomotive in the Twentieth Century (Jefferson, NC: McFarland & Company, 2018), p. 463. (Thanks to Chris Hohl for his 28 April 2019 email noting the class's stoker manufacturer and driver types as well as a comment on the last steam locomotive to haul a train on the IC.)

These behemoths were among the largest Mountains ever built.The firebox heating surface included 83 sq ft (7.7 sq m) of arch tubes (which Locobase considers counter-trending.). Other engines had the Type A that contained 1,242 sq ft (115.4 sq m) of heating surface. Coal entered the firebox through a Standard BK stoker.

Tom Morrison describes the different steam path in the newly minted and "cunning" Type HA--first tested in 1934. As saturated steam flowed down the dry pipe to the superheater header, it entered "a round pipe formed progressively into an annular space". Morrison offers a redrawn version of a diagram that shows the progression. Over most of their lengths, the flue's cross-section consisted of rings. In the center was the superheated steam heading back to the header; this was surrounded by a tube of flue gas. Outside of the flue gas tube was the "wet steam" layer, itself surrounded by another layer of flue gas tube.

Think of the wet steam flowing through a tube that is surrounded inside and out by flue gas. At the rear tubesheet end, it entered "a round pipe with three reverse bends at the back end of the flue." Then it returned down the central tube to the superheated side of the superheater. Elesco claimed that the H-A added 50 deg of superheat to the levels achieved by the Type A.

Like the fifty-five 2500s of the late 1930s (Locobase 2607), these engines had cast-steel engine beds that included the cylinders and air reservoirs. Unlike the 2500-class engines, which used reinforced boilers from the 2900-class Santa Fes, 2600-2619 were new from the rail up. The first ten rolled on web-spoke drivers and the last ten used Boxpok disc drivers.

Offering a prodigious power output on 70" drivers, the Mountains gave good service in freight service of all kinds, according to John S. Ingles (in Drury, 1993), "...even coal trains moved faster behind 4-8-2s than they had behind 2-10-2s."

Chris Hohl cites Stagner, Lloyd E. & Lee, Stephen A. Illinois Central Steam Finale. Pages 71, 73, & 77 as his source for his description of a final act: "#2613 was the last steam locomotive to handle a train on the IC. She was leased by the L&N (who no longer had steam locomotives at the time) to power a special centennial train on October 24, 1959 between Louisville and Nashville. Following that, she pulled two excursions along the IC's Kentucky Division on May 14, 1960 (to Dawson Springs) and October 2, 1960 (to Paducah), and, by doing so, she was the last steam locomotive to pull a train on the Illinois Central."