A crane includes a telescopic jib having telescopic jib sections and a base jib. The telescopic sections are arranged so that they can be axially moved into and out of the base jib individually. Locking pins are used hold the telescopic sections in place once they are in the required position. A hydraulic piston-cylinder unit arranged in the telescopic jib can push or pull individual jib sections when the respective locking bolts are removed. The movable portion of the piston-cylinder unit has two securing and locking units located at opposing ends of the movable portion. To move the jib section, one of the securing and locking units is connected to the jib section to be moved and the movement of the movable portions pushed or pulls the telescopic section. Once the jib section is moved to a desired position, the locking pin is reinserted to hold the position of the jib section. Since there are two securing and locking units, the piston-cylinder unit is approximately half the length of the telescopic section.