{HEAD ~ Leading end section} 12 and {TAIL ~ trailing end section} 14 are spaced at a distance, but substantially parallel to each other 
{ HEAD ~ Leading end section } 12 and { TAIL ~ trailing end section } 14 are spaced at a distance , but substantially parallel to each other
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH