(under the class definition) Apparatus in which means is provided for moving either a valve or a valve seat with respect to its cooperating member independently of opening or closing movement in such a direction or between such limits as to be ineffective to open or close the valve, usually to reduce friction or to prevent sticking or to equalize wear.
(1) Note. This subclass does not include a rotation of a reciprocating valve after it is seated merely for the purpose of perfecting the seating of the valve or any other movement which is performed as a part of the normal actuation of the valve. Such patents are classified on the basis of the actuator.
SEE OR SEARCH THIS CLASS, SUBCLASS:
242+, for movements of valves in mechanical cleaning.
315+, for valve movements associated with repair or tapping, especially subclass 329 for arrangements for bringing a new wearing surface of a valve or valve seat into operative position.
SEE OR SEARCH CLASS 251, Valves and Valve Actuation,
56, for pressure actuated valves with plural motions of the valve, and subclasses 215+ for mechanical movement actuated valves with plural motions of the valve, and see the search notes thereto.
