{HEAD ~ The control system} provides for prompt and variable adjustment by the operator of the amount of torque transmitted to downstream components and also provides for {TAIL ~ the prompt and easy resumption} of the trenching operation after an obstruction has been encountered 
provides for
{ HEAD ~ The control system } provides for prompt and variable adjustment by the operator of the amount of torque transmitted to downstream components and also provides for { TAIL ~ the prompt and easy resumption } of the trenching operation after an obstruction has been encountered
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH