a high pressure port and a low pressure port in fluid communication with {HEAD ~ said valve lands} on {TAIL ~ opposed axial sides} of said seal assembly 
a high pressure port and a low pressure port in fluid communication with { HEAD ~ said valve lands } on { TAIL ~ opposed axial sides } of said seal assembly
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH