Union Pacific Challenger #3985

Union Pacific ordered a total of 105 Challenger locomotives between 1936 and 1943v\.  The Challengers are a 4-6-6-4 articulated locomotive, with each set of drivers having its own steam cylinder.  They were designed for fast freight, with a top speed of 70 miles per hour. 

3985 last operated in regular revenue service in 1957, and was retired in 1962.  After a period of storage, it was parked in front of the Cheyenne, Wyoming depot on display.  In 1981,  a group of UP employees volunteered their extra time to restore the locomotive.  She originally burned coal and had a tender capacity of 32 tons.  In 1990, it was converted to burn No. 5 oil.

Today, it is the largest steamer still in operation.

After two years in the shop, 3985 was fired up on August 30, 2010.  I caught it pulling the Circus Train between Cheyenne and Denver on September 28th.  It then went on a tour to Sedalia, Missouri.


Builder: American Locomotive Works
Year: 1943
Tender: 14-wheeled
Water: 25,000 gallons
Fuel: 6,450 gallons No. 5 oil
Cylinder: Diameter: 21 in.  Stroke: 32 in.
Driving Wheel Diameter: 69 in.
Boiler: Inside Diameter: 94-11/16 in.  Pressure: 280 lbs.
Fire Box: Length: 187-1/32 in.  Width: 108-3/16 in.
Tubes: 2-1/4 in. Diameter: 45 x 20 ft. 0 in.
4 in. Diameter: 177
Wheel Base: Driving: 12 ft. 2 in. & 12 ft. 2 in.
Engine: 60 ft. 4-1/2 in.
Engine & Tender: 121 ft.10-7/8 in.
Weight in pounds: Leading: 102,300
Driving: 404,000
Trailing: 121,600
Engine: 627,900
Tender: 446,000
Evaporating Surfaces: Tubes: 527 square feet
Flues: 3,687 square feet
Fire Box: 500 square feet
Circulators: 81 square feet
Total: 4,795 square feet
Superheating Surface: 2,162 square feet
Grate Area: Removed, 1990
Tractive Effort: 97,350 lbs.

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