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