{HEAD ~ The present invention} comprises one set of drive gears and {TAIL ~ one set} of driven gears which are in a constant mesh position 
comprises
{ HEAD ~ The present invention } comprises one set of drive gears and { TAIL ~ one set } of driven gears which are in a constant mesh position
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH