The company Dosiertechnik GmbH presents its new generation of circular vibration screens (Fig. 1). The extremely robust machines with extraordinarily long service lives are equipped with overdimensioned spherical roller bearings (Fig. 2). Thus, the inside diameter of the bearing of the machine Victoria KS 2290/7000/2 (Figs. 3 and 4) is 180 mm. The very expensive oil lubrication of the bearings has been chosen deliberately.
Generally, Dosiertechnik GmbH attaches greatest importance to a robust quality and the associated long service life of the manufactured machines. For example, the largest serial machine with a width of 2400 mm and a length of 7000 mm has a machine body with a material thickness of 12 mm. It goes without saying that such machines, which are particularly manufactured for the harsh conditions of the rock and associated products industry, have a corresponding weight. That of the Victoria KS 2290/7000/2 is an impressive 14 t! This machine is driven by a foot-mounted geared motor of 30 kW. The power is directly transmitted to the central shaft of the screening machine via an articulated shaft. All machines are manufactured both with screen nettings of steel and with plastic screen components. In the main Dosiertechnik GmbH manufacture all screening machines in the single-deck and double-deck design as well as open and closed types.
The kind of drive is determined by the size of the screening machines. Vibration motors are the most frequently used type of drive. The functional performance of the screening machine is achieved by means of two counter-rotating vibration motors, which generate a linear, directional vibration. This linear, directional vibration makes it possible to install the machine horizontally. The result is very clean screening, since the material being screened has a long and intensive retention time on the screen surface (Fig. 5).
With vibrations motors, single-deck screening machines up to a size of approx. 2000 x 5000 mm can be manufactured economically. The weight of such a machine amounts to close to 7 t. Vibration motors as drive units can be used up to a maximum total machine weight of approx. 7500 kg. Then the above-described circular vibration screens are frequently used. However, circular vibration screens must have an inclination of 12–15 °C because the vibrations are “circular” in all directions in this case. For this reason they are called “circular vibration screens” as opposed to “linear motion screens”.
The third and certainly most impressive kind of drive is known as the directional exciter, which is a technically simple kind of drive. Also in this case, “directional, linear vibrations” are generated. A directional exciter is a kind of gearbox where two shafts with their centrifugal weights on the corresponding ends are driven by “forced synchronization” via gears. Screening machines with a width of 3 m and a length of 9 m can be driven by these directional exciters without any problem.
Dosiertechnik GmbH manufacture directional exciters with a working moment of 2600 cm/kg up to 16 320≈cm/kg. The maximum centrifugal force of the largest directional exciter is an incredible 51 310 kg! The weight of such a directional exciter of the size ES 7.B3 amounts to approx. 1800 kg. It is quite possible to use two or more exciters for large machines. It is possible to drive vibration machines with a total weight of 30 t using directional exciters from Dosiertechnik GmbH without any problem.