a first rotor which is connected to {HEAD ~ the output shaft} of {TAIL ~ the internal combustion engine} 
of
a first rotor which is connected to { HEAD ~ the output shaft } of { TAIL ~ the internal combustion engine }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL