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