US PATENT SUBCLASS 417 / 459
.~.~.~ Located within piston (e.g., valved piston)

Current as of: June, 1999
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417 /   HD   PUMPS

437  DF  EXPANSIBLE CHAMBER TYPE {40}
456  DF  .~ Relatively movable serial distributors {2}
458  DF  .~.~ Plural pressure responsive distributors {1}
459.~.~.~ Located within piston (e.g., valved piston)

DEFINITION

Classification: 417/459

(under subclass 458) Apparatus in which said two or more serially arranged pressure responsive distributors are both located within or carried by a piston type pumping member and serves to control fluid flow through a passage formed in the piston.

(1) Note. For definition of structure necessary to form a valved piston, see subclass 545 definition and (1) Note thereunder.

SEE OR SEARCH THIS CLASS, SUBCLASS:

261, for a piston having relatively movable serial distributors between stages of successive stage pumping

units.

SEE OR SEARCH CLASS

137, Fluid Handling, 512+, for plural direct responsive type valves.