UNION PACIFIC RAILROAD NO. 4012
Whyte System Type: 4-8-8-4 "Big Boy"
Builder: American Locomotive Company
Date Built: November 1941
Builder's Number: 69583
Cylinders (diameter x stroke in inches): 23-3/4 x 32 (four)
Boiler Pressure (in lbs. per square inch): 300
Diameter of Drive Wheels (in inches): 68
Tractive Effort (in lbs.): 135,375
Coal (in tons): 28
Oil (in gallons): Not applicable
Water (in gallons): 24,000
Weight on Drivers (in lbs.): 540,000; Total Weight: 1,200,000
Remarks: Overall length: 132 feet, 9-1/4 inches; retired by the Union Pacific in February 1962 after logging 1,029,507 miles. In good mechanical condition, but with small parts missing.
Union Pacific Railroad 4-8-8-4 Locomotive No. 4012
History: Brief background on the 19th century history of the Union Pacific Railroad appeared in the discussion of Union Pacific Locomotive No. 737. By the 20th century, the Union Pacific had gone through the processes of bankruptcy and reorganization, and early in the 20th century experienced rejuvenation in the hands of one of America's foremost railroad managers, the legendary Edward Henry Harriman. The company had lost its lines south of Denver extending southeastward across Colorado, New Mexico, and Texas, as well as its narrow gauge lines into the Colorado Rockies, during the bankruptcy of the 1890s, but under Harriman, it experienced not only a complete overhaul of its physical plant but also new construction across southwestern Utah, southern Nevada, and southern California to reach the growing metropolis of Los Angeles as well as a tidewater port at San Pedro. Thus the Union Pacific of the 20th century extended from Omaha to Cheyenne to Ogden to Portland, as well as to Denver, Salt Lake City, Las Vegas, Los Angeles, and San Pedro. It also owned a line between Denver and Kansas City. It was, furthermore, a thoroughly modern and up-to-date railroad.
Union Pacific Railroad Engine No 4012 is one of eight 4-8-8-4 "Big Boy" locomotives that have survived out of 25 that were built and operated. Its class remained among the largest steam locomotives in the United States, and locomotives of this type operated on no other railroad. Built in 1941, Engine No. 4012 is the epitome of modern, main line heavy-duty steam motive power. This class of engine was created to haul heavy freight trains over the mountain divide known as Sherman Hill between Cheyenne and Laramie in southeastern Wyoming and further west, across the deserts and then the Continental Divide in south-central Wyoming and the Wasatch Range in northeastern Utah, on the run between Cheyenne, Wyoming, and Ogden, Utah. The engine is one of 52 historic Union Pacific steam locomotives that escaped the scrappers' cutting torches. Engine No. 4012 is the only articulated locomotive (with more than a single set of drive wheels pivoting on more than one center) currently in the Steamtown collection. No. 4012 worked on the run between Cheyenne and Ogden for more than 20 years, rolling 1,029,507 miles before the Union Pacific retired the locomotive in February 1962.