Abstract: An apparatus for locating positions on a surface of a structural member indicating the presence of elements within and below the surface of the structural member by means of a detector (1) including a scanning head (3), a position measuring device (4) and an evaluation unit (5) all located within a housing (2). A marking device (6) is connected to and interacts with the evaluation unit (5) for automatically placing a visible marking on the surface of the structural member at the location of the elements scanned by the detector.

Abstract: An apparatus for locating magnetizable material (5, 6) within a structure (4) includes a scanning head (1) with a permanent magnet (28) for producing a magnetic field in the structure (4). Two field plates (30, 31), adjacent one another on only one pole face of the permanent magnet (28), are interconnected by a differential circuit and measure the magnetic field of the magnet disturbed by the magnetizable material (5, 6). The differential values measured by the pair of field plates form a differential measured signal for establishing, after differentiation, the location of the magnetizable material (5, 6) within the structure (4). The location of the magnetizable material (5, 6) within the structure can be shown on a monitor (7) of an evaluation unit (3).

Abstract: In a process using a hand-held drilling device for forming openings in a construction material containing steel reinforcing members, during the drilling step the electrical resistance between the drill bit and the reinforcing members is continuously measured. If the drill bit contacts the reinforcing member the measuring circuit is shorted out and the electrical resistance drops. The drop in resistance can be used as a signal for cutting power to the drilling device or for declutching or braking the device.

Abstract: A hand-held tool, such as a hammer drill or chipping hammer, includes a housing with a driving unit for supplying the driving force for the tool with the driving unit generating vibrations. A handle is mounted on the housing and is displaceable in the direction of the main vibration axis. A stop for the forward movement of the handle is provided by an electromagnet. The electromagnet is formed by a yoke, an armature and a magnetic coil and exerts a controlled constant force on the handle and the housing independently of the position of the handle relative to the housing. The electromagnet can be controlled depending on the position of use of the hand-held tool.