Hydraulic control system for a mining support

In a hydraulic system for controlling a mining support, the space 2 below the piston of prop 1 is connected via a distributor 21 to an adjustable pressure mains 32 and a drain mains 30. A second distributor 22 is connected to a high pressure mains 31 and the drain means 30, and has its outlet connected to the space 2 via a valve 14. The distributors 21, 22 are hydraulically controlled by a manual distributor 46, having its inlets connected to the mains 30, 31 and its outlets connected to control mains 43, 44 which are in turn connected to the control elements of the distributors 21, 22. The control elements of the distributors are connected to a pipe 8 connecting the mains 30, 31 to the space 3 above the piston and the control element of one of the distributors 21, 22 is connected to a pipe 10 connecting the mains 30, 31 to the space 2. The control allows a high initial setting pressure of the prop followed by an alteration of pressure to increase coal workability at the altered pressure.