Planetary gear units are a special form. With them, the power transmission is coaxial. In this case, the speed and torque of the input shaft – the central sun gear – are transmitted to an external annulus gear (on the output side) and transformed by three or more rotating planet gears. Their special feature: The input shaft and output shaft move in the same direction throughout this process. In combination with a servomotor planetary servo gearmotors provide particularly high dynamics and precision.
In right-angle gear units, in contrast, the drive shaft and output shaft are perpendicular to each other – with the result that the flow of force there is diverted at a right angle. There are three established versions of right-angle gear units. They include helical-bevel gear units, helical-worm gear units, and, exclusively from SEW‑EURODRIVE, the SPIROPLAN® right-angle gear unit.