Two mechanically-connected, vertical manometer tubes forming sight glasses (1, 2) share a common headspace containing air. The manometer tubes are connected by flexible tubing (7, 8) to initial and target locations. The common headspace is connected to a s...

The hand-held machine tool, e.g. a hammer drill and chisel, has a hose (4) filled with liquid (3) up to a working position (A), a sensor for detecting the hydrostatic pressure difference of the liquid and a signaling arrangement (10) for signaling a height...