In a spiral groove bearing {HEAD ~ a gap} between a surface portion which has grooves thereon and {TAIL ~ its opposing surface portion} is smaller than the gap between any other surface portion which does not have grooves thereon and its opposing surface portion 
In a spiral groove bearing { HEAD ~ a gap } between a surface portion which has grooves thereon and { TAIL ~ its opposing surface portion } is smaller than the gap between any other surface portion which does not have grooves thereon and its opposing surface portion
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH