The two-stage reduction of cycloidal gears makes solutions from Nabtesco Precision so successful. The reason is that the speed is reduced by the double cams. Vibration is reduced by the two-stage reduction principle and low inertia. The force is also distributed very evenly, thanks to the roller cam design, and this contributes to the minimum hysteresis loss and enormous resistance to shock loading. Consequently, cycloidal gears are as versatile as they are resilient.
The drive or servomotor is connected to the spur gear stage of the gearbox via a pinion. The rotating speed reduces at this point relative to the reduction ratio between the pinion and planetary gear. The planetary gears are connected to crankshafts which drive the cams using needle bearings. These cams rotate inside the case which is lined with pins.
The cam has exactly one eccentric section less than the pin ring has pins. A 360° revolution of the crankshafts therefore causes the cams to rotate one pin farther, whereby practically all the gear teeth are in continuous contact with the pins. The rotating movement is then transmitted from the input shaft to the crankshafts via the spur gear stage, and these then shift the cams in the pin ring and, consequently, generate a reduced speed with high precision. This technology enables the RV gears to absorb 5 times the rated torque in emergency-stop situations without suffering any damage. The resulting overall reduction is the same as the product of the two reduction ratios (spur gear stage and eccentric stage).