A friction testing machine and {HEAD ~ method} for measuring friction characteristics between {TAIL ~ a test sample} and a friction surface 
A friction testing machine and { HEAD ~ method } for measuring friction characteristics between { TAIL ~ a test sample } and a friction surface
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH