To restart the cutting wheel, {HEAD ~ the operator} slowly releases the pedal valve which starts {TAIL ~ the wheel} rotating again 
To restart the cutting wheel , { HEAD ~ the operator } slowly releases the pedal valve which starts { TAIL ~ the wheel } rotating again
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH