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