a spool feeding back excess discharged oil to {HEAD ~ a bypass passage} of said pump in accordance with differential pressure between upstream and downstream sides of said variable throttle mechanism when said excess fluid exceeds {TAIL ~ a predetermined value}; and 
a spool feeding back excess discharged oil to { HEAD ~ a bypass passage } of said pump in accordance with differential pressure between upstream and downstream sides of said variable throttle mechanism when said excess fluid exceeds { TAIL ~ a predetermined value } ; and
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH