Crane apparatus

A crane apparatus comprising:

• a body frame;
• a pair of drums rotatably mounted on the body frame;
• a hoisting accessory capable of attaching and detaching a load thereto and therefrom;
• a pair of wire ropes having an end taken up by the drums, and having the other end connected to the hoisting accessory;
• a traversing motor mounted on the body frame;
• hoisting accessory traversing means for traversing the hoisting accessory by rotating the drums by driving of the traversing motor to take up or pay out the wire ropes;
• speed change means for changing rotational speed of at least one of the drums;
• and
• control means for controlling the speed change means in a gear changing manner so that forces imposed on the drums by the wire ropes will be balanced.