There is one radial opening in {HEAD ~ drum} 5 for {TAIL ~ each crank arm} 6 
for
There is one radial opening in { HEAD ~ drum } 5 for { TAIL ~ each crank arm } 6
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH