In the exemplary embodiment shown in FIG 1, the relief opening is connected with a return line 41 that leads to pressure {HEAD ~ medium} reservoir 39, and a 2/2 way magnetic valve 42 having {TAIL ~ a spring return mechanism} is used as shutoff valve 40 
In the exemplary embodiment shown in FIG 1 , the relief opening is connected with a return line 41 that leads to pressure { HEAD ~ medium } reservoir 39 , and a 2/2 way magnetic valve 42 having { TAIL ~ a spring return mechanism } is used as shutoff valve 40
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH