Union Pacific #4017 - Big Boy - National Railroad Museum

The world's largest steam locomotive.

The “Big Boy” #4017

Weighing in at 1.1 million pounds and measuring nearly half a football field in length, the Big Boy locomotives were designed to haul heavy freight for the Union Pacfic railroad over the mountainous regions of Utah and Wyoming.

Originally, 25 of these giants were constructed in 1941 and 1944. They roamed the rails until 1959. The Union Pacific donated eight of them to museums across the U.S. The Big Boy preserved at the National Railroad Museum is the only one housed inside a climate-controlled facility.

Providing fuel and water to feed Big Boy was a major task. The 14-wheel tender was one of the largest built with capacity for 32 tons of coal and 24,000 gallons of water.

When it was built, Big Boy’s tender was designed to carry 28 tons of coal. This was enough to fuel the locomotive while pulling a 3,600 ton train between Ogden and Echo, Utah, a distance of 55 mountainous miles. The Union Pacific Railroad (U.P.) soon added the steel coal boards around the top of the coal bunker to prevent spillage and increase capacity. With the boards, the tener could carry 32 tons of coal.

The tenders on the first Big Boys (#4000 – #4019) carried 24,000 gallons of water. On the second order (#4020 – #4024), water capacity was increased to 25,000 gallons.

In addition to fuel and water, Big Boy’s tender carried other equipment. The stoker motor and fire fighting equipment were located in lockers on the fireman’s (left) side. Lockers on the engineer’s (right) side held train signal controls and small tools.

The coaling tower was a busy place during the steam era.

On the U.P., some coaling towers, like the one in Cheyenne, held up to a 650-ton supply and spanned four tracks. They also supplied sand, used by the locomotives to prevent slipping on wet rails and when getting started.

When a locomotive arrived at the coaling tower, it’s fire would be cleaned and ash pan emptied. The ashes and cinders fell into pits located between the rails. A conveyer system then loaded the waste into hopper cars. The cinders were dumped along the tracks as ballast.

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