Abstract: A drilling device comprises a drive motor (22), which sets a tool (36) in rotation, and a feed motor (14) which axially displaces the tool. Load sensors (12, 18, 20, 24) detect not only the tool feedrate (V) but also at least two of the three parameters, tool feed force (F), tool torque (M) and tool speed (U). An evaluation and control unit (70) evaluates the above-mentioned parameters and via control units (38, 42) activates the drive motor (22) and the feed motor (14) in such a way that the tool feed force (F) and the tool speed (U) or the tool torque (M) assume values at which the tool feedrate (V) for a specific ground hardness (H) is maximized.

Abstract: A boring tool with two driving heads which are used to sink a casing string and a borer string includes a controllable coupling mechanism fitted between the two driving heads. A mechanism is also provided for the lower driving head, such that the driving head is subjected to an additional downwards acting force. When both driving heads are coupled, the upper driving head is also subjected to an additional, downwards acting vertical force. In order to free the top end of the casing string, the coupling mechanism can be released so that the upper driving head can be fully raised, whilst the lower driving head remains in position adjacent to the ground.

Abstract: A drilling machine for a mobile drilling appliance which includes a housing which is adapted to travel along a jobber, a drive motor mounted on said housing, a pinion operatively connected to said drive motor, a step-down gear rotatably engaging said pinion, a driving socket located in the vicinity of a side face of said housing that contains a central opening which is adapted to receive a driving shaft that in turn is adapted to be connected to a drilling tool, and a driving ring positioned in said driving socket and engageable with said step-down gear.

Abstract: In a hydraulic pile driver (10), the lifting cylinder (34) acting on the driving weight (12) has an attached position indicator (46, 50), which produces a signal corresponding to the momentary position of the piston rod (32) of the lifting cylinder (34). This signal is used for reversing a 4/3-valve, by which the two working chambers of the lifting cylinder can be connected to a pressure line or return line.