The tractor sensing {TAIL ~ apparatus} 11 wherein the sensing means is {HEAD ~ a Hall effect sensor} 
The tractor sensing { TAIL ~ apparatus } 11 wherein the sensing means is { HEAD ~ a Hall effect sensor }
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD