a first pressure regulator in {HEAD ~ communication} with said first reservoir for controlling pressure supplied through said pressure supply conduit to said {TAIL ~ first reservoir}; and 
a first pressure regulator in { HEAD ~ communication } with said first reservoir for controlling pressure supplied through said pressure supply conduit to said { TAIL ~ first reservoir } ; and
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH