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