| 摘要 |
<p>The invention relates to a further configuration of the cutter-shield synchronous control according to the main application P 3019374.9, in which the cutter cylinders, by switching actuation of control valves, can be alternatively connected with their piston space to the pressure line of a pump unit or with their annular space to branch-flow lines of the pump unit, the annular spaces of the cutter cylinders being protected by pressure-relief valves. According to the invention, a pressure-cut-off device (50) is provided which is effective only during the drawing of the supporting frame and cuts off the pressure-medium feed for all cutter cylinders (16) at a system pressure which is lower than the response pressure of the individual pressure-relief valves (47). The pressure-cut-off device immediately stops the action of the drawing of the supporting frame if the drawing-up of the supporting frame meets with a certain resistance, for example due to an obstacle lying in the feed path. At the same time, it is ensured that the synchronous control cannot be disturbed through response of individual pressure-relief valves during the drawing of the supporting frame. <IMAGE></p> |
