In the transmission tecnique a low speed is frequently necessary; sometimes even of just some rounds per minute or fractions of rounds per minute. Some examples of this type may be found in different fields: environment, food, chemistry, concrete, ceramic and drive engineering industry.
In such cases, high gear ratio gearboxes are requested, because the power that need be transmitted is generally medium/low, while ouput torques often reach high values.
In order to achieve such high ratios, combined gearboxes are implemented such as:
Double worm reduction gear
Coaxial + parallel axle
Multi stage planetary gearbox
Planetary gearbox – Worm reduction gear
A comparison with similar amount of power transmission and gear ratio makes it possible to find the most effective solutions and techniques; generally, the solution where the planetary gearbox is combined with a worm gear, turns out to be the best one because the special characteristics of both may perfectly integrate.
In fact, the input worm gear reduction enables a first speed reduction with little effort because it does not allow a significant increase of the power but grants a very smooth operation and silence; while the output planetary reductions with their sturdy features allow a further decrease of speed (hence of power) with limited dimensions.
The gearbox structure is completely modular thus ensuring a quite high versatility which derives from the many possible executions. The screw-crown couple has a reduction ratio chosen to have the best performance. The screw is made of ground, case hardened and tempered steel. The crown has bronzed teeth with great features in terms of resistance and low friction.
The planetary reductions together with the worm gears offer a wide range of ratios. They have been designed and dimensioned to enhance their sturdiness.
Gears have teeth with corrected profiles, materials and thermal treatments ensure high resistance. Among the executions different outputs are available: for foot or flange-mounting, with swinging hollow shaft and shrink disc connection. The male output shaft are endowed with tapered roller bearings with high load capacity to be able to carry high radial loads and external axial loads.
The range reaches up to 45 kW power, from 1:400 a 1:5000 ratio (even higher on demand) and up to 400.000 Nm output torque.
The motor lubrications of the worm gear reducer and the planetary gearbox are separate. For the worm gear reducers, of a size ranging from MVF 49 to MVF 86 included, a permanent lubrication with synthetic grease is used; while oil is used for a size from MVF110 to MVF 210 included.
The planetary gearboxes on the other hand are always lubricated with oil.
Obviously, in all oil lubrication cases it is necessary to follow the guidelines for a correct maintenace.