Quick release knurled nuts GN 6303.1 are used in such applications where the nut has to be completely removed after the releasing operation and re-fitted rapidly for re-clamping.
The nut is tilted over the threaded spindle. When in position, the nut is brought into a straight position for meshing of the two threads on nut and spindle. The nut will then have to be turned only by a fraction of a rotation to achieve clamping.
Functional safety exists only if the clamping surface lies at a right angle to the threaded bolt.