1 pinion drives the axis (the "master") while the 2nd pinion is "preloaded" to eliminate the backlash (the "slave"). The preload is designed electronically which has a Exclusive motor controller; these units can be create to generate with each other for the duration of cycle situations when backlash isn't vital. https://gearbox-cvt64296.get-blogging.com/33197751/how-much-you-need-to-expect-you-ll-pay-for-a-good-gearbox-cvt