A gap is defined between {HEAD ~ each lobe}, the gap being defined at {TAIL ~ the radial outer edge} 
A gap is defined between { HEAD ~ each lobe } , the gap being defined at { TAIL ~ the radial outer edge }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL