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