The casing defines spaced apart internal frustoconical surfaces positioned to engage {HEAD ~ corresponding surfaces} of the segments in {TAIL ~ the same axial direction} 
The casing defines spaced apart internal frustoconical surfaces positioned to engage { HEAD ~ corresponding surfaces } of the segments in { TAIL ~ the same axial direction }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL