A casing is mounted to two respective outer peripheries of {HEAD ~ the two end caps} and accommodates {TAIL ~ the axle} therein 
A casing is mounted to two respective outer peripheries of { HEAD ~ the two end caps } and accommodates { TAIL ~ the axle } therein
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH