At {TAIL ~ the extreme end} of {HEAD ~ the shaft} 16 and closest to the wall 27, radially extending blades 28 are mounted; these may be straight, as shown, or in other embodiments curving and possibly extending tangentially to the shaft 16 
At { TAIL ~ the extreme end } of { HEAD ~ the shaft } 16 and closest to the wall 27 , radially extending blades 28 are mounted ; these may be straight , as shown , or in other embodiments curving and possibly extending tangentially to the shaft 16
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH