{HEAD ~ The belt} is toothed on one side and not on {TAIL ~ the other side} so that some slippage can occur 
is toothed not on
{ HEAD ~ The belt } is toothed on one side and not on { TAIL ~ the other side } so that some slippage can occur
HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH