In general, a friction test machine according to the invention comprises a sample holder configured to hold a sample in frictional engagement with a friction surface, and a motion device for effecting relative movement between the friction surface and {HEAD ~ sample holder} in {TAIL ~ a first direction} 
in
In general , a friction test machine according to the invention comprises a sample holder configured to hold a sample in frictional engagement with a friction surface , and a motion device for effecting relative movement between the friction surface and { HEAD ~ sample holder } in { TAIL ~ a first direction }
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