Each one of the drive gears constantly meshes with {HEAD ~ its counterpart member} of {TAIL ~ the driven gears} 
of
Each one of the drive gears constantly meshes with { HEAD ~ its counterpart member } of { TAIL ~ the driven gears }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL