The common shaft 138 runs adjacent to {HEAD ~ the front wall} 30 of {TAIL ~ the trailer} 20 
The common shaft 138 runs adjacent to { HEAD ~ the front wall } 30 of { TAIL ~ the trailer } 20
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH