The switch opens a solenoid valve which vents the hydraulic pumps which move the tracks of {TAIL ~ the trencher} in {HEAD ~ the forward direction} 
The switch opens a solenoid valve which vents the hydraulic pumps which move the tracks of { TAIL ~ the trencher } in { HEAD ~ the forward direction }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD