Abstract: A magnetic stirrer (1) with a magnet (3) driven in a rotating fashion by an electric motor (2) for the activation of a stirring bar magnet (7) inside a container (5) filled with a medium (6) has a digitally operated regulator (8), implemented with software, that is a software regulator. With this regulator, the rotational drive speed of the motor (2) can be held constant. At the same time, the change in the regulated quantity of this regulator (8) is detected and, in the event of a change in load, is reported to or displayed for the user as a trend or tendency of the viscosity change of the medium (6). In this way, the regulation of a constant rotational motor speed can be used at the same time for detecting changes in viscosity of the stirred medium (6).

Abstract: An upright mixing machine has one or more rotary vertical mixing tools having blades beneath a gear case for transmissions which orbit and/or rotate the tools. The gear case has an upper section which is rotatably installed in a housing, and a lower section which can be separated from the upper section to be thereupon lowered by an elevator for the purpose of convenient inspection of bearings, seals, gears and/or other parts which necessitate frequent inspection, cleaning, other maintenance or replacement. The elevator also serves to raise and lower a vessel for batches of material or materials to be mixed by the mixing tool or tools. At least one section of the gear case has one or more observation windows which are accessible for observation and manipulation of parts within the respective section not later than upon detachment of the lower section from and its lowering beneath the upper section.