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