| 摘要 |
<p>A cylindrical tool holder is mounted on a a housing containing a motor, the output shaft of which is coupled through a gear train to a driving ring. One axial face of the driving ring has cam surfaces engageable with cooperating cam surfaces on an axial face of an axially movable locking ring which is spring-urged toward the driving ring. The other axial face of the locking ring has axially facing gear-like teeth which are engageable with mating teeth on a flange formed on the housing and on a ring attached to the tool holder. A lock bolt mounted in the housing and operated by an electromagnet is withdrawn from a ring coupled to the tool holder to permit rotation to a new position and is extended to lock the holder near the new position.</p> |
