{TAIL ~ Certain portions} of {HEAD ~ the engine}, such as the flywheel, are left out of FIGS 4 6 to simplify the drawing 
{ TAIL ~ Certain portions } of { HEAD ~ the engine } , such as the flywheel , are left out of FIGS 4 6 to simplify the drawing
TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH