The eccentrics and cranks associated with each piston and {HEAD ~ cylinder} maintain {TAIL ~ their parallel relationship} while they are rotating 
The eccentrics and cranks associated with each piston and { HEAD ~ cylinder } maintain { TAIL ~ their parallel relationship } while they are rotating
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH