The outer gear constitutes a rigid gear 1 which is assumed to be fixed, while {HEAD ~ the inner gear} constitutes {TAIL ~ a flexible gear} 2 which is formed as a thin flexible ring so as to be flexible in its radial direction 
The outer gear constitutes a rigid gear 1 which is assumed to be fixed , while { HEAD ~ the inner gear } constitutes { TAIL ~ a flexible gear } 2 which is formed as a thin flexible ring so as to be flexible in its radial direction
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH