Control device for an extracting unit in the work face of a mine

摘要

The invention relates to a control device for an extracting unit in the face of a mine, for actuating the hydraulic actuator in the sense of drawing, stepping, setting, and having a plurality of main valves for connecting the actuator of the extracting unit to a main pressure line and a main return line, and a similar plurality of pilot valves, each associated with a main valve for adjusting same and connected to the main pressure line via a pilot pressure line common to all pilot valves and connected to the main return line via a return line common to the main valves and the pilot valves. The pilot pressure line (13) can be shut off and the return line (9) can be blocked off from the main return line (5) and connected to a measuring device (20) for measuring escaping hydraulic fluid. By selectively blocking off or unblocking the pilot pressure line (13), the inner leak rate of the valve block can be determined separately for the main valves and the pilot valves. The measuring device (20) can be a flow rate meter or other flow meter disposed in a bypass. By setting a check valve (22) in the bypass, the return line (9) is permeated only when a limit pressure is exceeded, but the bypass is always permeated, even when the pressure line is blocked off.