Gearbox Cyclo

There are two main types of gearboxes used on decanters. These are the epicyclic gearbox and the Cyclo gearbox, made by Sumitomo of Japan. However there are a number of decanters which have eliminated the gearbox by using a hydraulic system called a Rotodiff manufactured by the Swiss company Viscotherm. The Rotodiff and the Cyclo gearbox will be covered in more detail in Sections 2.3.7 and 2.4.15, respectively. 

The epicyclic gearbox is described in Section 2.2.7. The main alternative is the Cyclo type gearbox. The German Cyclo Company was founded in 1931 when Lorenz Braren invented the Cyclo gearbox. Shortly after this date Sumitomo of Japan licensed the device and eventually absorbed the Cyclo Company into its own group. 

The Cyclo gearbox, as stated, uses cycloid discs (see Figure 2.59) in place of the inner gearwheels of the Maun gearbox. The outer gearwheel is replaced by a series of rollers on pins. There is one less roller than the number of lobes on the cycloid disc. The drive pins of the output shaft are also fitted with rollers. 

The ratio of a Cyclo gearbox is from about 6 to a maximum of about 120. Therefore, for the decanter, many Cyclo gearboxes need only be single stage, which substantially reduces manufacturing costs. 

It remains to be described how the output shaft of the Cyclo gearbox is attached to the two cycloid plates. The output shaft has another ring of pins and rollers on its inner end. These rollers engage in corresponding circular holes in the two cycloid plates. The holes in the cycloid plates are of such a diameter that each hole wall is always in contact with its corresponding roller in spite of the eccentric throw of the cycloid plate. 

The Cyclo gearbox torque characteristics are different from those of the epicyclic. Its torque capability varies with differential speed while the maximum torque transmission of the epicyclic remains essentially constant for all differentials used. According to the manufacturer s performance data, the torque capacity of the Cyclo gearbox approximately halves when differential is increased from minimum to maximum. 

When an epicyclic gearbox is used, the conveyor rotates at a speed less than the bowl speed, while with a Cyclo gearbox the conveyor rotates at a speed above the bowl speed. This fact can have an effect on process performance... 

To calculate conveyor differential, the same relationships as described for the epicyclic gearbox are used, except, as already stated, the Cyclo differential is faster than the bowl speed whereas the epicyclic is slower. 

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