This movement causes {TAIL ~ the compensating spool} to reduce {HEAD ~ the opening} of one row of cross sectional holes and increase the opening of the other 
This movement causes { TAIL ~ the compensating spool } to reduce { HEAD ~ the opening } of one row of cross sectional holes and increase the opening of the other
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH