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.

Abstract: In the machine disclosed, two flexible welding cables carry capacitor discharge current from a capacitor bank in a capacitor charging welding set and produce a movable electrical connection between a welding gun and a base material onto which a welding element is to be welded. Both welding cables are fixed with respect to one another. According to one embodiment of the invention the cables are arranged to be equidistant from one another substantially over their entire length. They are arranged as close as possible to each other within the breakdown limits of the insulation. The cables are of a predetermined length.