the hollow part has an opening that opens at {HEAD ~ an end face} on {TAIL ~ a side} opposite the suction part side end face of the rotating shaft, and 
on
the hollow part has an opening that opens at { HEAD ~ an end face } on { TAIL ~ a side } opposite the suction part side end face of the rotating shaft , and
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH