{HEAD ~ The number} of {TAIL ~ gear teeth} between adjacent bulged regions differs between the two gears and the relative motion between the two gears is caused by shifting of the engagement regions 
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{ HEAD ~ The number } of { TAIL ~ gear teeth } between adjacent bulged regions differs between the two gears and the relative motion between the two gears is caused by shifting of the engagement regions
HEAD HEAD HEAD HEAD HEAD HEAD REL 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