(under subclass 172) Apparatus in which the piston is provided with a fluid conducting port or passage extending from the end face thereof through a portion of the piston and (1) communicating with a cavity in the piston for which the port or passage forms a restricted opening or (2) extending through a wall of the piston other than the end face (3) communicating with a cavity in the piston having a wall which is radially movable and forming a side wall portion of the piston.
(1) Note. See the search class notes under subclass 172 of Class 92 for a piston having an opening in the face thereof for admitting or exhausting working fluid to or from a working chamber, said opening being controlled by valve means.
(2) Note. The mere claiming of a flow through passage in a well type pump plunger is not sufficient for classification in this subclass. Such plunger is classified below on its other features.
SEE OR SEARCH CLASS
188, Brakes,
316+, for an internal resistance fluid type brake (e.g., dashpot) including a piston having a passage therethrough, for allowing fluid to pass from one side of the piston to the other.
