Self-hoisting crane and method of mounting and operating such crane

A method of mounting and subsequently operating a self-hoisting crane on a nacelle or on a tower of a wind turbine, whereby the self-hoisting crane includes a pedestal, a boom arm, a hook block and at least one cable adapted to lift or lower the hook block in relation to the boom arm for operation of the self-hoisting crane in its mounted position on the nacelle or on the tower, whereby the at least one cable extends from the hook block, out through the pedestal, from the nacelle or from the tower and to a cable winch arranged at the ground, whereby the self-hoisting crane is hoisted from the ground to the nacelle or to the tower by operating the cable winch arranged at the ground, and whereby the self-hoisting crane is operated in its mounted position on the nacelle or on the tower by operating the cable winch arranged at the ground, wherein the self-hoisting crane is provided with a cable crawler having at least one motor driven traction sheave adapted to transfer a pulling force to the at least one cable through friction, in that the cable crawler is shiftable between an active state in which the traction sheave transfers a pulling force or an at least substantial pulling force to the at least one cable and a passive state in which the traction sheave transfers no or at least substantially no pulling force to the at least one cable, in that, when the self-hoisting crane is operated in its mounted position on the nacelle or on the tower without any or at least substantially without any external load attached to the hook block, the cable crawler is operated in its active state, and in that, when the self-hoisting crane is operated in its mounted position on the nacelle or on the tower with an at least substantial external load attached to the hook block, the cable crawler is operated in its passive state.