PAWNEE, OKLAHOMA -- The big flywheel measures 12 feet in diameter.
It weighs close to 20,000 pounds.
The old Corliss Engine was the top of the line in steam generators in 1916.
"The valving system was developed by a man named Corliss," explains machinist David Britt.
Britt and other mechanics and gear heads like him managed to get the big engine running about 4 days every Spring.
Standing in front of the huge engine David says, "It was designed to run at 150 revolutions per minute. I could generate 480 volts and 526 amps."
There were several of these big steam engines that powered the old zinc smelter in Blackwell, Oklahoma.
It was the largest of its kind in the world during WWII.
This big machine is all that's left of a plant that employed 900 workers in its heyday.
Britt and other volunteers get it running once a year for spectators at the Pawnee Gas and Steam Engine Show.
"Is it kind of fun to see this thing run every year," asks a visitor? "Oh yeah," smiles Britt. "This is a big attraction."
Volunteer crews built the shed around the engine when they moved it to Pawnee.
David walked in here for the first time 16 years ago and never left.
He helped restore some of the other engines also housed in this building, one that powers every machine in a restored line-shaft shop.
"Back then, in the early 1900's workers had to make sure the boiler was going and the steam engine was running. You had to make sure the belts all stayed on," he explains.
Once a year they stoke the boilers.
"This is where the power comes from," says Britt while staring into the open boiler door.
A hundred years ago these steam powered machines were still the workhorses of American industry.
While other machines have long since rusted away, these still work as living history.
Britt says, "It's pretty exciting to me."
The annual Pawnee Gas and Steam Engine Show takes place the first weekend every May.
For more information go to http://www.oklahomathreshers.org