Illinois Central class 3500

The class 3500 was a heavy switcher similar to the USRA 0-8-0, but with a wider firebox for more power. This both increased the grate area and firebox surface. The grate was now 51 square feet and the firebox had 194 square feet. The drivers still had a diameter of 51 inches and the cylinders still measured 25 by 28 inches. The first 25 were delivered by Baldwin in 1921 and 15 more followed in 1923.

The third batch of 15, numbered from 3540, was delivered in 1927 and featured thermic syphons which added 57 square feet to the 191 square feet of the firebox walls. The tender still had a water capacity of 8,000 gallons, but the coal capacity had been increased from 12 to 13 tons. The final 15 locomotives, numbered 3555 to 3569, were built by Lima in 1929, but were virtually identical to the batch of 1927.