The Free Piston Engine

80lbs of thrust from a 20lb engine!

Wraps are about to be removed from what looks like the next inventive milestone. The free piston engine promises busses and trucks which will climb hills at top speeds–and great fuel economy too. it offers a more economical source of power for long range planes. One railroad, The Pennsylvania, sees it as a step beyond the diesel in locomotives. In time, it may even find its way into automobiles, giving 50 to 60 miles on a gallon of low-cost kerosene!

These are the things promised by the free piston engine, a radical new power concept. As the name implies, pistons are not connected to anything. In your present auto engine there are masses of moving metal-connecting rods, crankshaft, flywheel, etc. The new engine eliminates these parts. Two pistons slide freely in a horizontal cylinder. As they come together at the center they compress air so that the fuel injected will burn. in this respect the engine is like a diesel, requiring no spark plugs. As they free pistons fly apart, they compress air at the end of their stroke. Air compressed in the “bounce chamber” acts as a springy cushion, driving the pistons back to the center again. Flying back and forth, the pistons do useful work all the time, generating hot gases in the center of the cylinder, compressing air at the ends. These gases are drawn off and run through a conventional gas turbine where they give their power.

You can watch an info video by General Motors here.
GM was developing the free piston engine into “The car of the future” called the XB 500.

The free piston engine is by far the most efficient power plant ever developed–an important point considering the world’s dwindling stockpiles of fuels. The free piston engine is 40-45% efficient. It’s closest competitor is the diesel engine which is 35% efficient, while conventional gasoline engines are below even that number.

   Download a .zip file containing a Free Piston Engine advertisement here.

The free piston engine will operate on almost any sort of fuel: natural or manufactured gas, diesel, oil, or other petroleum products.

Includes:

• 8 page article on the engine
• Diagrams
• Articles
• Photos
• Original Patent
• Blueprints for construction
• Thesis on the theory behind the free piston engine
• .avi animation video showing the engine running
• Research done by MIT and various other universities