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