Drilling appliance

摘要

The drilling appliance has a sensor device (20) which reacts if persons or objects approach the drill string and cuts off the hydraulic drive in this eventuality. Since manual intervention in the monitoring area of the sensor device (20) is necessary for various assembly work, such intervention is generally only possible when the hydraulics are switched off. According to the invention, a timing element (D) is provided which briefly switches on the hydraulic drive upon actuation of a pushbutton (T2), even if the sensor device (20) has responded. In this way, the rotary motor (16) for coupling a pipe to the pipe string and for other assembly work can be utilised, but continuous operation which could lead to persons being put at risk is impossible. The operation has to be changed over from continuous operation to stepping operation by a change-over switch (37). <IMAGE>