A threaded shaft and retaining nut assembly having a shaft 4 with a first thread of a first hand along the shaft 4, and a second thread of a second hand opposite to said first hand along the shaft 4. The second thread at least partially overlaps said first thread. A tubular member is screwingly engageable for winding the shaft 4 into and out of the tubular member 3. A retaining nut 10 is screwingly engageable with the second thread for winding the retaining nut 10 back and forth along the shaft 4. In use, the second nut is engageable against an end of the tubular member 3 to prevent unintentional winding of said shaft. A locking member 12 is engageable with the tubular member 3 and the retaining nut 10 to effect a non-rotatable coupling between said tubular member 3 and retaining nut.