After {TAIL ~ the head portion} 46 is sensed by {HEAD ~ the magnetic sensor} means 58, a signal is sent to an active controller 50 
After { TAIL ~ the head portion } 46 is sensed by { HEAD ~ the magnetic sensor } means 58 , a signal is sent to an active controller 50
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH