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Five mind-blowing Big Boy facts

By Bob Lettenberger, Trains Associate Editor | August 19, 2022

Among the world’s largest steam locomotives, Big Boy tells a super-sized story

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Steam shooting from a large black articulated steam locomotive as it pulls its train.

Mind-blowing Big Boy facts

Steam shooting from a large black articulated steam locomotive as it pulls its train.
The sheer size of a Union Pacific Railroad Big Boy makes one stand in awe. To see No. 4014 run adds another dimension to the legendary story behind these mechanical wonders. Digging deeper into the Big Boy story and studying the little-known aspects of this steam locomotive will exponentially enhance your appreciation of what it represents. Cate Kratville-Wrinn

In the 1959 Union Pacific movie Last of the Giants the narrator comments, “ … There are no small parts on a Big Boy.” This is also true of the story that accompanies this colossus of the rails. As one digs into Big Boy’s details, everything — measurements, operating statistics, even the people involved — are large and, in some cases, larger than life. Come along and be amazed by five mind-blowing Big Boy facts.

No. 1: How about a dip in the pool? There is enough water in Big Boy’s boiler to fill a swimming pool measuring 14-feet wide by 28-feet long by 3 ½-feet deep. If you have grabbed your calculator — or slide rule, back in Big Boy’s time — to figure this out, let me save you the math. The boiler holds 10,500 gallons of water. Big Boy’s boiler, the part under pressure where water changes state from a liquid to a gas, is 45 feet long. It is made from three courses of cold-rolled, stress-relieved steel. Course one, the closest to the front, has an outside diameter of 97 11/16 inches. The steel is 1 11/32 inches thick. The steel thickness of course two increases to 1 3/8 inches. By the time we reach the third course, the outside diameter has been expanded to 106 9/16 inches with 1 3/8-inch steel. The boiler operates with a pressure of 300 pounds per square inch.

Boiler-smokebox-firebox assembly for a Big Boy steam locomotive is lowered onto its wheels with a massive indoor crane.
As another of the 4000’s comes together on the erecting floor, the boiler-smokebox-firebox assembly is lowered onto the driving wheels. When assembly is completed and the locomotive delivered to the Union Pacific, the boiler will be filled with 10,500 gallons of water. A gallon of water weighs about 8.3 pounds. That’s 87,150 pounds or 43 ½ tons of liquid. Trains collection

No. 2: I’d like to buy a Big Boy, but I’m concerned about fuel economy. How many miles can I get out of a tank? Are you ready for some sticker shock? Big Boy’s fuel economy is measured in gallons to the mile not miles to the gallon. No. 4014 began life as a coal burning locomotive, like all the other Big Boys. During restoration, it was converted to an oil burner. On the road, No. 4014 will consume 20 to 25 gallons of oil per mile depending on load, grade, and conditions. If you’re looking for something a bit more economical, could I show you a nice 0-6-0?

Inside cab of Big Boy steam locomotive. Focused on firebox.
Union Pacific fireman Austin Barker feeds sand into Big Boy No. 4014’s firebox. The draft will pull the sand through the flues to clean out any oil residue that has built up. This is a standard procedure for oil-burning steam locomotives. Bob Lettenberger

No. 3: William Jeffers, the Union Pacific Railroad president who ordered the Big Boys built, began working for the railroad at age 14. Why start a railroad career at such a young age? Jeffers was born January 2, 1876, in North Platte, Neb. His father, an Irish immigrant, was a laborer for the Union Pacific Railroad. Jeffers signed on with the Union Pacific as custodian for the North Platte depot. This career moved was necessitated by his expulsion from school after punching out his teacher. Jeffers had a hot temper that stayed with him his entire railroad career. At times, his angry, firm stance was useful, but generally created challenges. When he entered Union Pacific’s executive ranks in 1928, Jeffers was branded with a nickname: The Czar, in reference to the Russian leaders. It was said that when summoned to his office one did not know if you were about to be praised or fired.

Bald man sitting on a chair, smoking a cigar. He has a smiling, happy face.
William Jeffers, the Czar, loved a good party and could appear happy, jolly and fun loving. He was, however, a no-nonsense railroader who would unleash his temper on anyone that crossed him. Jeffers’ career with the Union Pacific began in 1890 as a janitor and concluded in 1953 as vice chairman of the board of directors. Trains collection

No. 4: Virtually every number used to quantify Big Boy is impressive. This includes the source of the numbers — the blueprints used to construct the locomotive. The set of plans developed to build the 4000-class tallied a little over 2,000 individual drawings. Everything on the locomotive is accounted for in one of these plans. The erecting diagram for the locomotive is the largest drawing in the set, measuring 12 ¾-feet long by 1 ½-feet wide. Remember, all of these plans were drawn by hand on a drafting table. When the Big Boys were designed there were no computers to assist with the math and no CAD systems to plot out the drawings.

Close-up of a large nut holding together part of a Big Boy locomotive.
Every part on a Big Boy is specified somewhere in the 2,000-plus drawings that make up the blueprints. Items like this nut and cotter pin — part of the reversing gear — are called out in the drawings. Bob Lettenberger

No. 5: Diesel locomotives carry along dried sand, which is applied to the rails in front of the wheels helping gain traction when starting or in slippery situations. Steam locomotives did so as well. Don’t think for a minute that the amount of sand carried by a Big Boy is any less impressive than the rest of the locomotive. Remember the engineer had to maintain control of 16 driving wheels on a locomotive weighing 1.18 million pounds plus the tonnage of the train. The 4000s were rated for 7,000 tons in some parts of their territory. Sitting atop the boiler, are two sand bunkers, one for each set of driving wheels. Each bunker holds 2 tons of sand.

Big Boy locomotive pulling train through freight yard.
Big Boy’s sand domes are visible atop the boiler of No. 4000. The locomotive would have been serviced — which included topping off the sand domes — before beginning this trip. The white patches on the domes are sand that spilled over the top. Trains collection

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