Abstract: A quick action tensioning nut of the type used to fasten a vehicle wheel on the mounting shaft or axle of a wheel balancing machine. The quick action tensioning nut has at least one pre-tensioned, somewhat semi-circular and radially movable thread segment which is mounted rotatably in the body of the nut. The thread segment is rotatable around an axis of rotation that is parallel to the mounting shaft, and the axis of rotation for the thread segment penetrates the fixed end of the thread segment. The nut also has a thread segment locking mechanism that locks the thread segment in a tightened state on the shaft. In order to release the thread segment from the tightened state, the end of the thread segment opposite the fixed end has a recess into which a thrust member can penetrate to rotate the thread segment away from locking engagement with the mounting shaft. The thread segment is constantly urged to rotate radially inwardly toward the mounting shaft by means of a spring.