The arrangement of the support pulleys and endless cable is such that by operation of the winder pulley , {HEAD ~ the cover} is retractably moved over {TAIL ~ the top} of the trailer body  
is retractably moved over
The arrangement of the support pulleys and endless cable is such that by operation of the winder pulley , { HEAD ~ the cover } is retractably moved over { TAIL ~ the top } of the trailer body
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH