| 摘要 |
<p>A device for supporting and actuating a turntable 2 for a machine tool comprises a base member 3, a member 5 fitted for supporting the turntable 2 and mounted on the member 3 for rotation about a vertical axis and movement along said axis. The member 5 is fixed to a screw 13 which is screwed into a central threaded bore in an actuating member in the form of a gear 11 drivable in either direction about said axis. A dog clutch 8 engageable and disengageable by axial movement of the member 5 is provided between member 5 and member 3. A first one- way clutch arrangement 16 acts between the base member and the turntable supporting member and a second one-way clutch arrangement 21 acts between member 11 and member 5. The direction of rotation of said actuating member relative to the turntable supporting member in which the clutch 21 arrangement is freewheeling is opposite to the direction of rotation of the member 5 relative to the member 3 in which the clutch arrangement 16 is freewheeling, and the screw threaded engagement between screw 13 and gear 11 operates to move the member 5 axially relative to the member 11 and member 3, in consequence of rotational movement of the member 11 relative to the member 5 in order to effect engagement and disengagement of the dog clutch 8. <IMAGE></p> |
