In this case, {HEAD ~ the gap} 23 is provided between the internal gear 3 and {TAIL ~ the iron ring} 22 as shown in FIG 2 
is provided between
In this case , { HEAD ~ the gap } 23 is provided between the internal gear 3 and { TAIL ~ the iron ring } 22 as shown in FIG 2
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH