Horizontal adjustment device, for aluminium mobile gantry crane, for variable spacing of the side supports. Supplied = assembled. Can be used for infinite adjustment of the side frame along the horizontal beam. Individual and flexible adjustment of the effective length of the mobile gantry crane. Simple and quick assembly. Use of the horizontal adjustment device enables one of the side supports to slide along the horizontal beam. Side support spacing can be adjusted as required. Price only applies in combination with the crane system (retrofitted on request)