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