Thus, {HEAD ~ the wheels} 23 are faced with {TAIL ~ the slope} 311, and the propped surfaces 312, 313 
are faced with
Thus , { HEAD ~ the wheels } 23 are faced with { TAIL ~ the slope } 311 , and the propped surfaces 312 , 313
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH