A locking arrangement includes at least a rotatable part, a stationary part with respect to the first part, and a locking member having locking protrusions. At least one working plane passing through the locking protrusions is defined in a locking position where compression forces are concentrated which are reaction forces to external forces tending to rotate the parts relative to each other. The parts have locking protrusions defining gaps for receiving the locking protrusions in the locking position for preventing the parts from being rotated to each other.