Seismological evidence for differential rota-tion of the Earth''s inner core

A spindle control for a multiple spindle automatic bar machine tool is disclosed with the machine tool being one having a spindle carrier journaled in a frame for indexable rotation about an axis. A plurality of bar receiving rotatable spindles are journaled in the spindle carrier and an electric clutch and brake unit is provided within the length of the spindle carrier for each spindle with the clutch and brake unit having a small enough outside diameter to pass through one of the end openings of the spindle carrier during manufacture and having a sufficiently large inside diameter to accept bar workpieces through the hollow spindle. Collets are provided in each spindle to grip the bar workpieces and are actuated by means which has no relative rotation between the collet actuator and the finger holder sleeve on each spindle, yet permits relative indexing movement between each sleeve and the collet actuator. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.