Glossary of Motor Terms
Wave reduction gear
As explained in the illustration, when the green ellipse-shaped body (wave generator) is driven by the motor, the blue hard inner gear ring rotates at reduced speed. The red external gear, which consists of either a flexible cup or belt, allows for backlash-free Vernier-type speed reduction. There are many rollers between the elliptical plate and flexible external gear ring.
![](/-/media/www-nidec-com/technology/motor/glossary/item/wave_reduction_gear-01.jpg)