{TAIL ~ a reversible motor} operatively connected to said throttle valve for operating {HEAD ~ said throttle valve} 
{ TAIL ~ a reversible motor } operatively connected to said throttle valve for operating { HEAD ~ said throttle valve }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD