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