US PATENT SUBCLASS 251 / 38
.~.~.~ Pilot valve seated in motor or valve element

Current as of: June, 1999
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251 /   HD   VALVES AND VALVE ACTUATION

12  DF  FLUID ACTUATED OR RETARDED {12}
25  DF  .~ Pilot or servo type motor {8}
33  DF  .~.~ Choked pressure type servo motor {8}
38.~.~.~ Pilot valve seated in motor or valve element {2}
39  DF  .~.~.~.~> Controls inlet to choke chamber
40  DF  .~.~.~.~> Tilting pilot valve

DEFINITION

Classification: 251/38

(under subclass 33) Subject matter in which the pilot valve co-acts with a seating surface therefor mounted on either the servo-motor element or the main valve so as to partake of the motion thereof.

(1) Note. Some disclosures identify the pilot valve as a mere relief valve and disclose that the main valve is mechanically opened by the overtravel of the pilot valve actuator, but these are here classified so long as their structure provides for alternating of the high and low pressure conditions in the expansible chamber.

SEE OR SEARCH CLASS

137, Fluid Handling,

221+, for Larner-Johnson type valves having an internal pilot valve for an internal servo-motor, subclass 490 for line condition change responsive pilot or servo controlled valves in which the pilot valve is within the main valve head and subclasses 630+ for a main valve and concentric type balancing valve successively operated to open or closed position.