Control device for an advancing support in underground mining

An improved control for an underground mining working support unit arrangement of the type having an adjacent support and arrangement hydraulically connectable to the working support unit arrangement, a plurality of hydraulic supports composed of piston-cylinder units having a cylinder with a bore and a piston member slidably mounted in the bore of the cylinder for displacement responsive to a hydraulic working medium admitted in first and second compartments in the cylinder on opposite sides of the piston member, means for admitting the hydraulic working medium to the bore, the admitting means having control conduits connected to each of the compartments of each piston-cylinder unit and control valve means interposed in the conduits for controlling the admission of the hydraulic working medium, the admitting means being hydraulically connected to the adjacent support unit arrangement, the hydraulic supports supporting a plurality of load points, and each of the conduits having a nominal diameter which permits direct control of the hydraulic supports, the improvement comprising means for successively connecting selective hydraulic supports for supporting several of the load points to the control valve means, and said connecting means including at least one reversing valve operable to alternately connect control valves to selected hydraulic supports.