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