IF brake-lining manufacturers would insist on holding the values of friction coefficients to 0.3 or 0.4, many of their troubles would cease, in the opinion of the author, who asserts that the main objections to high friction-coefficients are rapid wear, greater liability to cause scoring, and instability.
The first results of tests on molded brake-lining materials were so superior to tests on woven material that further development of molded materials was carried on. Regardless of the type or make of molded material tested, it was found that the friction-coefficient value remained much more uniform than did that of woven material and that, without exception, the friction value and general characteristics of molded material were not changed by wear conditions.
Molded material shows longer life than woven material, according to tests, and the author thinks that possibly this is because of the completeness of the saturation of the molded material. Discussing the wide variation of friction-coefficient values, usually found in woven material and absent in molded material, the author feels that atmospheric moisture is responsible, and that woven material is affected to a much greater degree because of a much deeper penetration of moisture. In conclusion, he states that molded lining usually reaches its full efficiency after about 300 miles of service. It resists oil to a marked degree and, after it has been running in oil for some time, it can be succesfully restored by washing in clean gasoline.