A single pinion drives the axis (the "grasp") when the 2nd pinion is "preloaded" to remove the backlash (the "slave"). The preload is developed electronically that has a Distinctive motor controller; these methods may also be put in place to push collectively through cycle situations when backlash is not crucial. https://tysoniigea.blazingblog.com/32741123/a-simple-key-for-gearbox-cvt-unveiled