US PATENT SUBCLASS 417 / 495
.~.~.~ Pumping member comprises valved piston

Current as of: June, 1999
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417 /   HD   PUMPS

437  DF  EXPANSIBLE CHAMBER TYPE {40}
490  DF  .~ Pumping member position controlled port {8}
493  DF  .~.~ Including plural controlled inlet or outlet flow paths {2}
495.~.~.~ Pumping member comprises valved piston

DEFINITION

Classification: 417/495

(under subclass 493) Apparatus including a piston type pumping member provided with a fluid passage extending from the end face thereof through the opposite end of the piston or through a side wall portion thereof, said passage being provided with a relatively movable valve means to control the flow of fluid through said passage.