When {HEAD ~ top plate} 10 is lowered by displacement of {TAIL ~ cylinder} 62, fluid extension ducts 182 compress springs 186 and thereby maintain the seal 
When { HEAD ~ top plate } 10 is lowered by displacement of { TAIL ~ cylinder } 62 , fluid extension ducts 182 compress springs 186 and thereby maintain the seal
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH