Abstract: A pressure reducing valve of an air damping system of motor vehicle chassis makes available a constant output pressure when the input pressure varies. The pressure reducing valve has a housing with a general longitudinal axis, at least one fluid input opening and at least one axial fluid passage opening. In the housing a valve piston with a valve body is mounted displaceably which forms a seat valve with the axial fluid passage opening. An elastic diaphragm arranged stationarily in the housing is coupled to the valve piston and forms two axially active differential pressure areas. A pressure return passage penetrates the valve piston and guides an output pressure present downstream of the seat valve onto the elastic diaphragm.

Abstract: A laser levelling instrument with a levelling base (7) and fine self-levelling of the laser beam (10) has an inner cylinder (5) which bears aligning elements and is suspended in an oscillating manner inside an outer cylinder (1). The laser levelling instrument is characterized in that the outer cylinder (1) and the inner cylinder (5) form a capacitor system with opposite electrode faces; the outer cylinder (1) is joined at right angles to the base (7) and is centred with respect to the beam axis (11); and signals for detecting the oscillating position of the inner cylinder (5) may be derived from the capacitor system.

Abstract: An apparatus for aligning a laser leveling instrument along a building line can remain standing unchanged on its base throughout both horizontal and vertical leveling operations. The light source is located in the base of the instrument. The instrument head can be swung through 90.degree. and houses a rotating prism which generates the vertical plane, and an adaptor. The adaptor includes a prism for deflecting the light from the source into the rotating prism and a triple prism which, when brought into the light path, deflects the light coming from the base perpendicular to the generated vertical plane, projecting it onto the building line.