The internal gear is made of an elastic resin and is separated from {TAIL ~ the casing} of {HEAD ~ the system} or a metal ring fitted in the casing by a predetermined gap 
The internal gear is made of an elastic resin and is separated from { TAIL ~ the casing } of { HEAD ~ the system } or a metal ring fitted in the casing by a predetermined gap
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH