Means are provided to prevent jumping of the belt from the second pulley when {HEAD ~ the head} is in {TAIL ~ other positions} 
is in
Means are provided to prevent jumping of the belt from the second pulley when { HEAD ~ the head } is in { TAIL ~ other positions }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL