The distance of {TAIL ~ each roller} from the rotation axis and the angles between adjacent rollers are predetermined such that, at any time during a rotation cycle, two rollers engage {HEAD ~ at least one currently active tooth} 
The distance of { TAIL ~ each roller } from the rotation axis and the angles between adjacent rollers are predetermined such that , at any time during a rotation cycle , two rollers engage { HEAD ~ at least one currently active tooth }
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD