{TAIL ~ The set} of wheels is arranged substantially on a line extending through {HEAD ~ the arbor} 
{ TAIL ~ The set } of wheels is arranged substantially on a line extending through { HEAD ~ the arbor }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD