Exact Measurement of Power Loss in Automotive Transmission and Axle for Fuel Economy

Many problems have been encountered in attempting to clarify the behaviors of drivetrain components from the standpoint of the power loss. This paper describes the analytical and experimental research to develop a method of measuring the total power losses of transmission and axle whereby far more accurate test results can be obtained than by the conventional means with good repeatability. In this pursuit, the power loss of the drivetrain is divided into two groups, i.e. gear tooth friction loss and lubricant churning loss, with the resulting practical formulation which permits calculation of these two losses on a separate basis. Also covered are the results so far achieved by means of practical application of the above approach and concept in both bench and field testings aiming at improvement of fuel economy and prediction of the drivetrain lubricant temperatures in the field operation.