(under subclass 179) Subject matter wherein said shaft is hollow along its length, or wherein the shaft is formed of plural concentric layers of material.
SEE OR SEARCH THIS CLASS, SUBCLASS:
18+, for a flexible coupling between rotary fluid-conducting shafts.
SEE OR SEARCH CLASS
138, Pipes and Tubular Conduits, appropriate subclasses for a hollow pipe.
175, Boring or Penetrating the Earth,
320+, for a tool shaft detail, and see the reference to Class 175 in the search class notes under the class definition of Class 464.
