The first paper in this series described the results of laboratory measurements and road evaluation tests on a series of tread stocks over a wide range of severities, and indicated the various advantages and limitations involved in the laboratory and road measurements. It is the purpose of the present paper to describe in greater detail the abrasion instrument used in these studies. The laboratory measurement of abrasion resistance was reviewed by Buist in 1950. The paper describes 21 laboratory abraders. Developments in abrasion instruments and methods which have since appeared in the literature have been primarily concerned with modifications and refinements on these basic types. A novel type of instrument described by Newton, Grinter and Sears, uses stationary knife blades to scrape a rotating rubber disc. The research group at the Emeryville Shell Development laboratories investigating characterization of elastomeric properties some years ago decided that its requirements in laboratory abrasion testing could best be satisfied by an abrader of the Dunlop-Lambourn type because of its versatility in providing control of angular velocity, load, slip, energy transfer, and temperature. Also, in the Lambourn abrader, the motor-driven vulcanizate wheel driving a braked abrasive wheel resembles the action of a driven tire rolling on a pavement. A given section of the tire tread surface is subjected to stressing and abrasion only during the portion of the cycle when in direct contact with the abrading surface. Cooling and relaxation occur during the portion of the cycle when the section is not in contact with the surface. Viscoelastic and abrasion mechanisms can operate in the laboratory at frequency levels approximating those encountered in road tests.

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