In essence, this puts {HEAD ~ the tracks} of {TAIL ~ the trencher} into a neutral gear and releases the forward pressure on the cutting wheel 
of
In essence , this puts { HEAD ~ the tracks } of { TAIL ~ the trencher } into a neutral gear and releases the forward pressure on the cutting wheel
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH