{HEAD ~ a peripheral surface} for engaging {TAIL ~ a pulley cable} for causing said pulley to rotate 
for engaging
{ HEAD ~ a peripheral surface } for engaging { TAIL ~ a pulley cable } for causing said pulley to rotate
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH