An impeller is mounted in the trailing end of the concavity and {TAIL ~ a stator} trails {HEAD ~ the impeller} 
An impeller is mounted in the trailing end of the concavity and { TAIL ~ a stator } trails { HEAD ~ the impeller }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD