This also pressurizes the track pumps so that {TAIL ~ forward motion} of {HEAD ~ the trencher} is also started 
This also pressurizes the track pumps so that { TAIL ~ forward motion } of { HEAD ~ the trencher } is also started
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH