| 摘要 |
A record disk drive is disclosed which includes a rotating drive shaft and means for receiving a record disk. A torque-transmitting helical spring clutch drivingly interconnects the shaft and the disk. The clutch includes a first coil portion which is in driven engagement with the shaft upon rotation of the shaft in a certain direction relative to the receive disk. A second coil portion of the clutch is continuous with, but eccentric to, the first coil portion. Abutment means on the second coil portion are normally in driving engagement with a received disk, but means are provided for shifting the second coil portion toward a position concentric with the first coil portion, whereupon the abutment means moves out of engagement with the received disk, and thereby disengages the clutch. The shifting means may be a cylindrical sleeve which is axially slidable over the helical spring clutch to move the second coil portion toward its concentric position relative to the first coil portion. In such case, the axial end of the sleeve may have an internal parabolic cross section. Alternatively, the shifting means may be a cylindrical sleeve axially slidable within the helical spring clutch; whereupon the sleeve may have an external paraboloid cross-section. In order to gain stability, the helical spring clutch may be formed of coils having rectangular cross-sectional shapes to inhibit telescoping. If a torque-limiting feature is desired, the first coil portion of the clutch may be wound upon the drive shaft in a direction such that rotation of the drive shaft tends to unwind the first coil portion, to at least partially release the gripping pressure of the first coil portion on the drive shaft.
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