AFTER making an extensive examination of many brake lining materials, Mr. Oetzel comes to the conclusion that no short test can show adequately the characteristics of a piece of lining.
It seems that no one value of coefficient can be used to represent a piece of lining, according to the author, because the coefficient varies so widely with temperature and pressure and with the degree of service curing.
He says further that there seems to be no way to reduce the characteristics of a lining material to some simple “index number”; that the best that can be said is that, when correlated with road tests, characteristics determined from samples form a useful basis of judgment.
