magnetic pole detecting means disposed in an internal space of the housing member for detecting {HEAD ~ the position} of a magnetic pole on {TAIL ~ the permanent magnet member} 
magnetic pole detecting means disposed in an internal space of the housing member for detecting { HEAD ~ the position } of a magnetic pole on { TAIL ~ the permanent magnet member }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL