{HEAD ~ The body} has a base, a rear cover, a front cover, a bearing seat and {TAIL ~ a middle liner ring} 
has
{ HEAD ~ The body } has a base , a rear cover , a front cover , a bearing seat and { TAIL ~ a middle liner ring }
HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL