Abstract: The invention relates to a crane truck with a drivable undercarriage and a superstructure supported on the undercarriage to be rotatable by means of a slewing rim, the superstructure having a counterweight, which is movable by an elevating mechanism consisting of two piston-cylinder drives between an elevated operation position and a driving position when it rests lowered onto a support on the undercarriage. The piston rods of the piston-cylinder drives are drivable to rotate between a locking and unlocking position referred to the counterweight. The desired positions of the piston rods in their positions of crane operation and release as well as their locking and unlocking position are displayable by means of proximity switches on the piston-cylinder drives, so as to eliminate operation errors and disturbances in the hydraulic system of the piston-cylinder drives by way of various control units.