{TAIL ~ The bulged regions} are shifted by the rotation of {HEAD ~ the wave generator} 3, causing the flexible gear 2 to rotate in the opposite direction from that in which the wave generator 3 rotates 
{ TAIL ~ The bulged regions } are shifted by the rotation of { HEAD ~ the wave generator } 3 , causing the flexible gear 2 to rotate in the opposite direction from that in which the wave generator 3 rotates
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH