The free-steering axle follows the direction imposed by the tractor. The steering angle is +/- 15° depending on the tyre size. When driving on the road at more than 15 km/h or when reversing, a hydraulic device ensures a powerful lock and a perfect alignment of the rear axle with the front one, guaranteeing the safety of the tractor-trailer combination. A shock absorber ensures the stability of the free-steering axle and prevents excessive vibrations. A steering axle reduces the tyre wear significantly (less slippage) as well as the torsion on the whole vehicle in tight bends.