a main cylindrical member, extending in {HEAD ~ the axial direction} of said {TAIL ~ housing sections}, for movably containing said housing sections, 
of
a main cylindrical member , extending in { HEAD ~ the axial direction } of said { TAIL ~ housing sections } , for movably containing said housing sections ,
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH