Abstract: A pressure limiting valve has a piston sliding inside a piston bore in a piston guide. A valve spring and a spring plate move in a spring sleeve which has an adjusting screw at an end opposite the spring plate. The spring plate has flow-through openings. The piston extends into a blind bore in the spring plate. The piston guide, which forms the bottom of the spring chamber, has a funnel-shaped recess which extends to the inside wall of the spring sleeve. The spring plate support surface for the valve spring is below the top of the piston.

Abstract: The present invention relates to an adjustable support element for use in underground mining or tunnel construction, particularly for securing mining cavities at the longwall face and headway. The invention is a single use prop made of inner and outer telescopable tubes which can be filled with a hardenable building material core. The tubes have drainage boreholes for draining excess water from a liquid filling material pumped within the tubes after the prop has been braced between the roof and floor of the mines. Plural bands connected between the outer and inner tubes enable the telescopic movement of the tubes.

Abstract: A barrier post (1) for closing a variety of access paths as well as parking lots and parking spaces in particularly easy to use and entails no risk to the user, for example by the presence of clamping points, because the swivel hinge (4) is divided into a lower and an upper hinge (6, 7). The lower hinge (6) constitutes the link between the base (13) and the displacement shaft (11) and then only after that with the tube (5) whereas the upper hinge (7) is the link between base (3) and tube (5). The displacement shaft (11) is connected, either directly through its movement nut (15) or indirectly through a guide (8), a sliding guide (9) and movement unit (15), with the tube (5) and raises or lowers the tube by appropriate rotation. This is achieved by means of a motor (13) with drive (12) accommodated in the tube (5), but which the movement nut (15) together with the whole tube (15) is pivoted upwards or downwards, depending on the direction of rotation.

Abstract: For the temporary blocking of the access to parking places, driveways and cess roads a post is used, which is anchored in the ground and is foldable about an articulation arranged over the ground, whereby a drive is located in the post which can be activated over a receiver in correspondence with a portable emitter. Thereby, the post is suitably built as a hollow body, so that the drive and the remaining parts can be safely lodged therein. This way, the barrier post can be remote-controlled without difficulty from an approaching vehicle by means of a portable emitter, or for instance in the case of blocking the access to football stadiums, from a control center.

Abstract: Alpha gypsum hemihydrate is obtained by calcining calcium sulfate dihydrate, generated with flue-gas desulfurization of power plants or by chemical process, e.g. in the production of phosphoric acid. The calcining process comprises producing initially a dispersion from calcium sulfate dihydrate and diluted, sulfuric acid solution and heating same at a predetermined rate to about 373 K with industrial, dust-free waste heat, whereupon the solid components are separated from the aqueous sulfuric acid and are dried. An alpha gypsum hemihydrate practically free from anhydrite II is obtained from a solution of sulfuric salts in the diluted sulfuric acid. An addition of magnesium oxide yields a hemihydrate with a high degree of fineness and avoids blooming effects.