Advanced ATF Technology Meets Future Global OEM Needs 2007-01-1975
Fuel economy is a well known driver of change in transmission and automatic transmission fluid (ATF) technology. It has led to reducing transmission components' size and weight and also to adding continuously slipping torque converter clutches and other refinements. Resulting ATF performance improvements include: 1) reduced viscosity to lessen churning losses and improve fuel economy [1,2,3]; 2) high shear stability to ensure adequate fluid film thickness throughout the life of the vehicle; 3) high viscosity index (VI) to improve fuel economy; 4) improved gear and bearing protection due to lower viscosity; 5) high static friction to improve clutch holding capacity; 6) high dynamic friction for good clutch engagement performance; and, 7) long-term anti-shudder performance to enable aggressive use of controlled slip torque converter clutches for fuel economy.
Our paper reports on the development of new ATF technology specifically designed to meet all seven of the ATF fluid performance areas mentioned above. Data is presented from the JASO LVFA (Low Velocity Friction Apparatus), shear stability and film thickness, and FZG pitting testing to establish gear protection properties for lower viscosity formulations with fuel-saving properties. We conducted friction testing on a wide range of composite materials from various suppliers. Results show that the new fluid technology is superior to existing commercial fluid technology worldwide and can address all the major concerns enumerated above.