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A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device (e.g., a piston in a closed cylinder) and a load device (e.g. a gas compressor or a linear alternator).
The purpose of all such piston engines is to generate power. In the free-piston engine, this power is not delivered to a crankshaft but is instead extracted through either exhaust gas pressure driving a turbine, through driving a linear load such as an air compressor for pneumatic power, or by incorporating a linear alternator directly into the pistons to produce electrical power.
The basic configuration of free-piston engines is commonly known as single piston, dual piston or opposed pistons, referring to the number of combustion cylinders. The free-piston engine is usually restricted to the two-stroke operating principle, since a power stroke is required every fore-and-aft cycle. However, a split cycle four-stroke version has been patented, GB2480461 (A) published 2011-11-23.

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  1. Tony617

    Quick question on the AK-47 gas piston

    I have question on the AK-47 gas piston. With my M14 you keep the gas piston and cylinder dry. Is it the same for AK-47 to keep it dry as well? What about the gas cylinder too? Just using CLP to cleaning and lubing right now. Thank you.
  2. Hal OPeridol

    AR gas piston builds using VZ58 system

    I recall a while back, notsure if this forum, folks using the gas system from a VZ58 kit and modding it for use in an AR build. Anyone else remember, or might know what site it was on?
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