| 摘要 |
<p>The turret comprises a base 2, a tool-bearing member 4 rotatably mounted for movement along, and rotation about, an axis X-X relative to base 2, and a control member 8 mounted on the base for rotation in either direction about axis X-X. A threaded coupling 19 is provided between the control member 8 and the tool-bearing member 4, and a toothed face clutch 15, 16 is provided between the tool-bearing member 4 and the base 2. A first unidirectional coupling is provided between the member 8 and the member 4 and comprises a spring catch 36 carried by member 4 and engageable selectively with recesses in the member 8. A second unidirectional coupling is provided between base 2 and member 4 and comprises a spring catch 32 carried by member 4 and engageable selectively with recesses 31 in the base. The catches 32 and 36 are aligned in a bore 37 in member 4 and a pre-stressed resiliently yielding member 38 having a predetermined yield force is placed between the catches 32, 34. Its ends are at such an operating distance from the catches so as to just engage both catches when one of the catches is fully engaged in its respective recess and the other is fully displaced from its respective recess. If the torque applied to the member 4 during indexing, for example during braking, exceeds a predetermined value, the member 38 yields resiliently to allow both catches to move fully out of their respective recesses and allow further rotation of the member 4. <IMAGE></p> |
