US PATENT SUBCLASS 137 / 538-- .~.~.~.~ Piston-type valves

US PATENT SUBCLASS 137 / 538
.~.~.~.~ Piston-type valves

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

455	DF	LINE CONDITION CHANGE RESPONSIVE VALVES {11}
511	DF	.~ Direct response valves (i.e., check valve type) {14}
528	DF	.~.~ Reciprocating valves {5}
535	DF	.~.~.~ Spring biased {5}
538		.~.~.~.~ Piston-type valves

DEFINITION

Classification: 137/538

(under subclass 535) Valves in which the valve is a cylindrical plug cooperating with a hollow cylindrical valve seat, there being ports in the cylindrical wall of either piston or seat which are opened and closed by reciprocating movement of the piston in the cylindrical seat.

SEE OR SEARCH THIS CLASS, SUBCLASS:

792, for piston type expansible chamber devices.

SEE OR SEARCH CLASS

251, Valves and Valve Actuation,

62+, for piston type fluid pressure actuators for valves, and subclasses 318+ for reciprocating valves of this class, and see the search notes thereto.