Vacuum Engine

The working principle is similar to the hot air engine, except that this engine draws hot air into the cylinder.Heat is drawn into the cylinder, at BDC the inlet valve shuts the heat then cools down this in turn creates a vacuum, this vacuum plus air pressure then forces the piston back up the bore which gives the power stroke. A constant burning f...
Found on http://www.diracdelta.co.uk/science/source/v/a/vacuum%20engine/source.html

Vacuum engine

A vacuum engine (also called `flame-licker engine`) derives its force from air pressure against one side of the piston, which has a partial vacuum on the other side of it. At the beginning of an outstroke, a valve in the head of the cylinder opens and admits a charge of burning gas and air, which is trapped by the closing of the valve and expand.....
Found on http://en.wikipedia.org/wiki/Vacuum_engine

Vacuum Engine

A vacuum engine is an engine of small power, which derives its force from air pressure against one side of the piston, which has a partial vacuum on the other side of it. At the beginning of an outstroke, a valve in the head of the cylinder opens and admits a charge of burning gas and air, which is trapped by the closing of the valve and expands. T...
Found on http://www.probertencyclopaedia.com/browse/GV.HTM
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