A control means, for a mine roof support having hydraulically extensible prop means and some other pressure-fluid-operated component (e.g. a hydraulic ram for advancing the support), comprises a control valve having selectable positions in one of which (the prop extend position) it will select for a supply of hydraulic pressure-fluid to said prop means. The control means also include a valve device having a position in which it will provide for a supply of pressure-fluid to the prop means and having means adapted to cause it to move to that position, when the control valve is operated to the prop extend position, and to keep it in that position even position. the control valve is operated from the prop extend positon. By this arrangement a pressure-fluid supply to the prop means will still be maintained so as to ensure proper setting thereof and to make up any leakage of fluid. The operation of the control valve from the prop extend position may be, for example, to bring it into a neutral position or to a position in which pressure-fluid is supplied to the advancing ram of the support.In one preferred embodiment of the invention the valve device has a pressure-fluid responsive movable member and is adapted to be connected, for its operation, to a pressure-fluid supply via the control valve.