CTLGroup was contracted to conduct qualification tests on friction wedges for freight car applications in the North American market. Friction wedges were tested in accordance to the Association of American Railroads specifications (AAR) Manual of Standard and Recommended Standards (MSRP) M-980 “Friction Wedge Performance for Railcars – Dynamic West Test”.
The objectives of the tests were to evaluate the wear performance of cast friction wedges. The samples under test, which were extracted from cast friction wedge casting and wear plates using a precision machining process, were measured and prepared in accordance with the AAR specifications.
Wear testing occurred using a constant clamp for of 750 lbs. on the friction wedge coupons. Under this clamp force, the wear plate was oscillated vertically between the clamped friction wedge coupons using a trapezoidal waveform with an amplitude +/- 0.5 inches for a total of 100,000 cycles.
Pre- and post- measurements were taken to evaluate the performance of the system through the duration of the test. This included dimensional measurement, weight and surface roughness which allowed for the determination of the physical wear on each component as well as the energy dissipation and loss characteristics of the assembly throughout the testing process.