An apparatus to be employed in combination of claim 1 for a hermetically sealed reciprocating piston gas expander unit comprising:

a reciprocating piston gas expansion mechanism having one or more pistons, each piston is enclosed in a sealed cylinder, and is operatively connected to a power shaft through a connecting rod, and an eccentric or crank arm;

http://www.patentstorm.us/patents/5327987/claims.html

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