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