(under subclass 179) Devices under the class definition comprising a packer or plug set in final position within a surrounding conduit, (the setting tool or conduit which
supported the packer or plug during insertion into the surrounding conduit having been withdrawn) combined with a centrally positioned longitudinally extending member, other than the aforesaid setting tool or supporting conduit and not a mere retrieving means for the packer or plug which is run into the surrounding conduit after the packer or plug is set.
(1) Note. The centrally positioned longitudinally extending member must be more than a mere piston, fluid driven into the well or plug, per se. Usually the centrally positioned member is a central conduit, receptacle or pump barrel. For a piston, fluid driven into the well cooperating with another such piston see subclass 153.
SEE OR SEARCH THIS CLASS, SUBCLASS:
115+, for a central chamber sealed with respect to a prepositioned surrounding conduit.
179+, and the subclasses there noted for packers or plugs assembled in a well.