US PATENT SUBCLASS 137 / 489
.~.~.~ Choked or throttled pressure type

Current as of: June, 1999
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137 /   HD   FLUID HANDLING

455  DF  LINE CONDITION CHANGE RESPONSIVE VALVES {11}
485  DF  .~ Pilot or servo controlled {3}
488  DF  .~.~ Fluid pressure type {2}
489.~.~.~ Choked or throttled pressure type {4}
490  DF  .~.~.~.~> Pilot valve within main valve head
491  DF  .~.~.~.~> Choked passage through main valve head
489.3  DF  .~.~.~.~> Loose fitting piston
489.5  DF  .~.~.~.~> Pilot controls supply to pressure chamber

DEFINITION

Classification: 137/489

(under subclass 488) Apparatus which includes a pressure chamber having both a valved passage and an unvalved passage for ingress and egress of fluid, the relative sizes of the passages being such that a different pressure may be maintained in the chamber when the valve passage is open than is the case when it is closed.

SEE OR SEARCH CLASS

251, Valves and Valve Actuation,

33+, for choked or throttled pressure type servo actuated valves which do not include means sensing a change in fluid condition in the line, and see the search notes to subclass 33.