A self centering construction 19 wherein said axial movement means comprises a second liquid spring operable in tension and {TAIL ~ compression} on each of {HEAD ~ said liquid springs} 
A self centering construction 19 wherein said axial movement means comprises a second liquid spring operable in tension and { TAIL ~ compression } on each of { HEAD ~ said liquid springs }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD