Loading crane and its control system

A loading crane, comprising a boom, a control site having a seat for a crane operator, said control site being laterally offset from said boom, a directional control valve supported at one side of said control site to be substantially in alignment with said boom, said directional control valve being constructed to hydraulically control the crane to provide different operations of the crane, and control means for influencing actuator spindles of the directional control valve for the control of the crane, said control means comprising a control lever arrangement adjacent to said operator seat for being operated by the operator, and a mechanical rod-driven control lever system having one end connected to said lever arrangement and an opposite end in operative engagement with the directional control valve such that the actuator spindles are in a substantially horizontal position, wherein said control lever arrangement comprises a control lever positioned at the operator seat for pivotable movement left and right and forward and backward, said mechanical rod-driven control lever system comprises a first pair of longitudinally movable connecting rods, a first pair of ball joints connecting said control lever to said first pair of connecting rods to transmit longitudinal movements to said first pair of connecting rods in correspondence with direction of pivotable movement of said control lever, a second pair of connecting rods, a second pair of ball joints connecting said second pair of connecting rods to said first pair of connecting rods to produce torsional movement of said second pair of connecting rods in correspondence with longitudinal movement of said first pair of connecting rods, and a third pair of connecting rods connected to said second pair of connecting rods to be moved longitudinally to and fro upon torsional movement of said second pair of connecting rods, said third pair of connecting rods being connected to said actuating spindles of said directional control valve.