Illinois Central 4-8-2 "Mountain" Type Locomotives

Class 2400 (Locobase 1356)

Data from IC 9 -1928 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

15 built by Alco-Schenectady in 1923 (works #64569-64583). This was the first batch of Mountains and the firebox heating surface included 48.3 sq ft of arch tubes. The subsequent batches -- see Locobase

Class 2415 (Locobase 6702)

Data from IC 9 -1928 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

The first 15 locomtives in the IC's 4-8-2 fleet are described in Locobase 1356. The current record shows the later batches of Mountains (Schenectady works #67039-67058 in 1924, Lima works #6884-6909 in 1925). The biggest difference came in the firebox heating surface where the arch tubes were replaced by 115.5 sq ft of thermic syphons.

Class 2500 (Locobase 6703)

Data from IC 1955 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. The specs refer to the version that had 2 arch tubes and 4 thermic syphons. Together the two types of appurtenances contributed 132 sq ft 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.

One by one, beginning in March 1937, 55 of this class were delivered over the next 5 years. 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 collection. The specs show the variant that had Type HA superheaters (which had larger-diameter superheater elements); other engines had the Type A that contained 1,242 sq ft of heating surface.

These behemoths were among the largest Mountains ever built. They kept the square diameter x stroke dimensions of the earlier 2400s, but increased the size. The firebox heating surface included 83 sq ft of arch tubes (which Locobase considers counter-trending.). The specs show the variant that had Type HA superheaters; other engines had the Type A that contained 1,242 sq ft of heating surface.

Like the fifty-five 2500s of the late 1930s, 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.

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."

Specifications
Class	2400	2415	2500	2600
Locobase ID	1356	6702	6703	3156
Railroad	Illinois Central (IC)	Illinois Central (IC)	Illinois Central (IC)	Illinois Central (IC)
Whyte	4-8-2	4-8-2	4-8-2	4-8-2
Road Numbers	2400-2414	2415-59	2500-2554	2600-2619
Gauge	Std	Std	Std	Std
Builder	several	Alco-Schenectady	IC	IC
Year	1923	1924	1937	1942
Valve Gear	Walschaert	Walschaert	Walschaert	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	19.50'	19.50'	18.25'	18.25'
Engine Wheelbase	42.25'	42.25'	42.25'	42.25'
Ratio of driving wheelbase to overall engine wheebase	0.46	0.46	0.43	0.43
Overall Wheelbase (engine & tender)	77.79'	77.79'	83.33'	92.34'
Axle Loading (Maximum Weight per Axle)	60800 lbs	62300 lbs
Weight on Drivers	243500 lbs	247000 lbs	280500 lbs	293880 lbs
Engine Weight	362500 lbs	367500 lbs	409500 lbs	423893 lbs
Tender Light Weight	191500 lbs	205300 lbs	219500 lbs	370500 lbs
Total Engine and Tender Weight	554000 lbs	572800 lbs	629000 lbs	794393 lbs
Tender Water Capacity	10000 gals	10000 gals	11000 gals	22000 gals
Tender Fuel Capacity (oil/coal)	18 tons	18 tons	24 tons	26 tons
Minimum weight per yard of rail on which locomotive could run	101.46 lb rail	102.92 lb rail	116.88 lb rail	122.45 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	73.50"	73"	70"	70"
Boiler Pressure	225 psi	225 psi	240 psi	275 psi
Cylinders (dia x stroke)	28" x 28"	28" x 28"	30" x 30"	30" x 30"
Tractive Effort	57120 lbs	57511 lbs	78686 lbs	90161 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.26	4.29	3.56	3.26
	Heating Ability
Firebox Area	384.70 sq. ft	451 sq. ft	518 sq. ft	467 sq. ft
Grate Area	75.40 sq. ft	75.40 sq. ft	88.30 sq. ft	88.30 sq. ft
Evaporative Heating Surface	4643	4710	5246	5195
Superheating Surface	1227	1227	1285	1619
Combined Heating Surface	5870	5937	6531	6814
Evaporative Heating Surface/Cylinder Volume	232.67	236.03	213.74	211.66
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	16965	16965	21192	24282.50
Same as above plus superheater percentage	20511.18	20471.16	25361.61	30052.00
Same as above but substitute firebox area for grate area	104650.52	122446.84	148780.45	158938.66
Power L1	24322.90	24704.12	22133.10	28890.26
Power MT	880.87	882.00	695.83	866.91