The Only Running Tree

An all-wood gasoline engine that really runs!

| February 2007

  • PaulGorrell
    Right: Paul Gorrell with his all-wood engine.
  • PaulGorrell3
    'Counterclockwise from above: The Louisville Slugger tongue and front axle; the camshaft, timing gear and end of the pushrod; a side view of the timing gears and pushrod; the cylinder, piston and connecting rod; the Tinker Toy fuel mixture adjustment with chock in the intake; and the valves, return rockers, fuel mixer and gas tank. '
  • PaulGorrell1
    'Below: The laminated edge and end grain cylinder with toolbox, hopper removed. '

  • PaulGorrell
  • PaulGorrell3
  • PaulGorrell1

Like barns built 100 years ago, this wooden, all-original one-of-a-kind engine, built in the first 4-1/2 months of 2006, is made of 65-year-old wood and held together with wood pegs. It's the only one known to exist; it was designed and home-built by an old crippled guy some say had too much time on his hands, and/or just didn't know any better!

Why? Just because I like engines and ingenuity, and people like wood. I also didn't know of one that ran and people like something different. I have a 9th grade education, so I thought I should be able to do it, and there is not one speck of metal anywhere. It even has flint stone ignition.

Since I don't know the exact horsepower for this engine, I call it 8 "tree-power," as I used at least eight different kinds of wood for this project: Pecan for the flywheels, gears, pushrod and rocker arms; oak for the frame, wheels, axles and bolsters; hickory for the inner frames, cylinder, rod and tongue; honey locust for the rails, etc.; walnut for the platform, nuts, etc; cedar for the hopper; mahogany for the pulley; rubber tree for bands, etc., and unknown kinds of wood for the internal parts, possibly ebony.

Everybody likes the original powerized Louisville Slugger tongue. All of the parts were laminated cross-grain with DAP Weldwood glue to hold a strong shape. The engine was assembled with oak pins that can be driven out to disassemble and repair this possibly high-maintenance engine. The hex nuts in the photos are "walnuts." The wood gas tank, fuel line and mixer are coated with gas tank sealer. All wood parts that rub are penetrated with Minwax wood hardener and sprayed with coats of Teflon Dry Lube high performance formula; they are lubricated with extra virgin olive oil.

The cylinder is laminated hickory edge and end grain with one ring piston, 3-3/4-inch bore and 7-inch stroke. There is no compression stroke, to reduce heat and stress. The engine is 4 feet long, 3 feet tall and 2 feet wide. It usually starts very easy with a slow quarter turn pull on the flywheel. When I fired it up the first time, I wondered if it would turn into a wood splitter, but it was the best, worst-sounding music I ever heard. It really just sounds like other gas engines.

It fires halfway down, the intake stroke becoming the power stroke. I enjoy seeing peoples' faces when a dead tree "pops" back to life! This 8-stroke, 9-cycle gasoline engine runs best slow. It cools by drawing air in and out the exhaust three times between fires. I didn't run it for long intervals so it would last through the first season, when it ran 19 days in shows in five states. Most people like to see how easy it starts and takes off.


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