SAE Standards Works
E-34 Propulsion Lubricants Committee
ARP6156 - WAM High Speed Load Capacity Test Method
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Lavern D. Wedeven
WAM High Speed Load Capacity Test Method
The WAM High Speed Load Capacity Test Method provides lubricating performance characteristics for the qualification of aviation oils under SAE specification AS5780. It is one of two alternate test methods designed to substitute for the Ryder Gear Test Method. The test consists of a rolling/sliding contact between a ball and disc test specimens fabricated from AMS 6265 (AISI 9310) gear steel. The test characterizes the oil for wear, scuffing and traction (friction) coefficient. Two test protocols are used. They differ only by the entraining (rolling) velocity. A Standard test protocol is used for typical 5 cSt engine oils. A Modified test protocol is used for high load carrying oils. These may include gearbox oils, 9 cSt oils and Enhanced Ester oils. Oil qualification for lubricating ability is based on a scuffing load stage with AMS 6265 (AISI 9310) gear steel. The same test method is used for the evaluation of othe bearing and gear materials, in addition to oils.
Oil qualification for lubricating ability from the early days of jet engines has been conducted with a gear test for scuffing (Ryder Gear Test Method). With gear precision, availability and cost issues associated with a gear test, alternate test methods were developed based on sound tribological theory and advanced testing techniques. The alternate test methods became approved test methods for oil qualification under AS5780. The WAM High Speed Load Capacity Test Method, described in AIR4978, Appendix E is widely used for aviation oil qualification. Its tribological basis, linkage to service performance and acceptance by the aviation community provided the rationale for the SAE E-34 Committee to recommend the development of a standard described in an ARP document.