Abstract: A positioning cylinder assembly for subterranean mining applications has a rotary potentiometer connected through a friction wheel transmission with the spindle of the cylinder which is rotated when the piston is axially displaced therein. The friction wheel assembly comprises a pinion wheel connected to the spindle and a hollow wheel connected to the rotary potentiometer, that not only matches the pitch of the spindle to the rotary spring of the potentiometer but also functions as a slip clutch for zero setting of the potentionmeter and the piston.

Abstract: The pressure measuring device has a housing in which a pressure chamber is located in a pin extending freely in the interior of the housing from a base. The pressure chamber wall is deformable elastically under an applied pressure. In the free end portion of the pin a magnetoresistive sensor is mounted which is moved with the chamber wall in a displacement occurring because of pressure changes in the chamber and thus is displaced relative to a permanent magnet. The magnet is mounted slightly transversely in the end portion of a compensating sleeve which surrounds the pin with wall contact. The change of the magnetic field at the sensor on displacement causes a proportional resistance change of the sensor so that an electrical signal proportional to the pressure change is generated which is a measure of the pressure. An amplifier for the signal from the magnetoresistive sensor can be mounted inside the housing adjacent the permanent magnet or the magnetoresistive sensor.

Abstract: An apparatus for the contactless measurement of geometrical dimensions includes a light source emitting a light beam, a first deflector deflecting the light beam at an angle toward an object to be measured, a receiver receiving the light beam and a second deflector for deflecting the light beam reflected by the object toward the receiver. The second deflector rotates about an axis extending perpendicularly to the light beam reflected by the object. The axis of the light beam emitted by the light source extends parallel to the axis of rotation of the second deflector. The light beam conducted to the receiver extends coaxially to the axis or rotation of the second deflector. This apparatus requires no calibration, but only an adjustment. For measuring a distance it is sufficient if only the second deflector rotates. If both deflectors rotate, the second deflector must rotate at a substantially higher rate of rotation than the first deflector. The first deflector is vertically adjustable and lockable.

Abstract: A wall supporting arrangement, especially for supporting mine gallery walls, comprises a supporting frame for a wall to be supported and including at least two frame elements located in a plane which is transverse to the elongation of the wall and are spaced from one another in this plane, and a plurality of shape-retaining shell-shaped connecting elements distributed along the frame elements and connecting the latter with one another in spacially fixed relationship. The supporting frame may include two such outer frame elements and two such inner frame elements connected with one another. In this case each of the connecting elements includes two shell portions connected with one another and including mounting formations for mounting the four frame elements with one another. The supporting frame may include a plurality of frame portions located laterally adjacent to one another in a circumferential direction of the supporting frame.