Quick release knobs are used in such applications where the knob has to be completely removed after the releasing operation and refitted very rapidly for re-clamping. For starters, the knob is tilted over the top of the threaded spindle. The knob can then be adjusted rapidly to the position necessary. When in position, the knob is tilted upright into a straight position for engaging of the threads on knob and spindle. The knob will then have to be turned only by a fraction to achieve clamping.