Fluid Performance in Automatic Transmissions

In order to determine transmission fluid requirements, fluid performance in automatic transmissions has been investigated using engine-transmission-dynamometer test apparatus. It was found that the rate of fluid oxidation was essentially the same using two-speed and three-speed transmissions. Further, the rate of fluid oxidation was very similar in part throttle and full throttle cycling tests. In addition, the effect of fluid frictional deterioration on shift performance was similar between the two transmission types. It is concluded that fluid performance in the two-speed transmission can be evaluated using the three-speed transmission, or vice versa. The significance of the full-scale laboratory test results was confirmed by establishing a correlation with car test results.