US PATENT SUBCLASS 417 / 523
.~.~ Including valved piston

Current as of: June, 1999
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417 /   HD   PUMPS

437  DF  EXPANSIBLE CHAMBER TYPE {40}
521  DF  .~ Plural pumping chambers {7}
523.~.~ Including valved piston {5}
524  DF  .~.~.~> Unitary or interconnected elements form inlet or discharge distributors for plural chambers
525  DF  .~.~.~> Common piston includes valves for plural axially aligned chambers {2}
528  DF  .~.~.~> Fluid conduit for one chamber extends through portion of another
529  DF  .~.~.~> Parallel laterally spaced relatively movable pistons
530  DF  .~.~.~> Including nonvalved piston

DEFINITION

Classification: 417/523

(under subclass 521) Apparatus in which at least one of the chambers is defined in part by a piston, said piston or element rigid therewith (e.g., piston rod) having a pump fluid conducting passage formed therein and the means for controlling fluid flow into or out of the chamber including a movable valve member in flow controlling relationship with said passage, said valve member being located within or carried by said piston or element rigid therewith.

(1) Note. For classification under this definition, the expansible chamber pump must be provided with a pump fluid conducting passage which is physically located within the

piston or element rigid therewith. A pump having relatively movable piston portions for controlling flow from one side of the piston to the other via a flow path formed between the piston and a cylinder sidewall (i.e., pump fluid flows around the piston) is excluded under this definition; see subclasses 555.1+, below, and the search note therein to Class 92 for such subject matter.

SEE OR SEARCH THIS CLASS, SUBCLASS:

545, for valved piston-type pumps not involving plural pumping chambers and see the search notes thereto for valved pistons elsewhere classified.