Crane apparatus

摘要

A crane apparatus is disclosed. A hoisting accessory is traversed by rotating rotating drums by driving of a traversing motor to take up or pay out wire ropes. Continuously variable transmissions are provided for changing rotational speeds of the rotating drums. A control device controls the continuously variable transmissions in a gear changing manner so that forces imposed on the drums by the wire ropes will be balanced. Thus, torques acting on the pair of drums are canceled out in all areas in which the hoisting accessory moves, whereby the capacity of the drive motor can be reduced.