Abstract: A description is given of an inclined feed shaft for feeding particulate material to a mill. The feed shaft is configured for rotation about its longitudinal axis. The feed shaft may be configured so that any incipient formation of coatings on a wall of the shaft is continuously cleaned off and dislodged from that wall by descending material particles in the feed material so that the feed shaft is self cleaning.

Abstract: An endoscope with a sealed housing having inner magnetic structures coupled to a displacement element and outer magnetic structures coupled to an adjustment element. The inner and outer magnetic structures are magnetically coupled to each other through the wall of the housing and are displaceable parallel to the wall. The inner magnetic structure is displaceable toward and away from stop and the outer magnetic structure magnetically drives the inner structure. The outer magnetic structure can be affixed beyond the stop position of the inner structure in a secured adjustment position.