US PATENT SUBCLASS 417 / 59
.~ Radially expansible piston portion controls pump and motor chamber intercommunication


Current as of: June, 1999
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417 /   HD   PUMPS

56  DF  DRILLED WELL FREE PISTON-TYPE PUMP {4}
59.~ Radially expansible piston portion controls pump and motor chamber intercommunication


DEFINITION

Classification: 417/59

(under subclass 56) Apparatus in which at least a portion of the piston is capable of expansion and contraction in a direction perpendicular to its axis of reciprocation to thereby provide a valving action with the chamber in which it reciprocates to allow or interrupt fluid communication between the pump and motor chambers.

SEE OR SEARCH THIS CLASS, SUBCLASS:

555.1+, and see the search notes therein, for other fields of search for radially expansible and contractible pistons.