US PATENT SUBCLASS 251 / 25
.~ Pilot or servo type motor

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

12  DF  FLUID ACTUATED OR RETARDED {12}
25.~ Pilot or servo type motor {8}
26  DF  .~.~> Alternative pressure sources or pilot valve
27  DF  .~.~> Servo failure responsive control of main valve
28  DF  .~.~> Fluid actuated pilot valve {1}
30.01  DF  .~.~> Electrically actuated pilot valve {1}
31  DF  .~.~> Double or oppositely acting motor units
32  DF  .~.~> Latched pilot valve
33  DF  .~.~> Choked pressure type servo motor {8}
47  DF  .~.~> With separate dashpot or choked fluid retarder

DEFINITION

Classification: 251/25

(under subclass 12) Subject matter in which the valve is actuated, at least in part, by a fluid pressure motive means deriving its power from either the fluid line or a separate source of fluid pressure and controlled by an auxiliary or pilot valve or valves.

(1) Note. Fluid pressure servo-motors having valves both for the inlet and the outlet or vent of the pressure chamber are in this subclass.

SEE OR SEARCH CLASS

91, Motors: Expansible Chamber Type, appropriate subclasses for expansible chamber motors, per se.

137, Fluid Handling,

46, for inertia responsive systems having servo mechanisms, subclass 58 for centrifugal governor controlled servo actuated valves, subclasses 82+ for pressure modulating relays or followers, subclass 105 for pulsators with pulsation responsive pilot valve, subclasses 191 and 195 for gas and liquid separating traps having servo-control of the valves, subclasses 219+, especially subclass 222 for Larner-Johnson type valves having hollow telescoping sections which function as servo units, subclasses 413+ for fluid pressure servo-motor operation of a level responsive valve, subclasses 485+ for servo-operated line condition responsive valves, and subclasses 596.14+ for pilot actuated supply and exhaust valves, and subclasses 625.6+ for pilot actuated supply and exhaust multiway valve units.