Efficiency Characteristics of Manual and Automatic Passenger Car Transaxles

Up to the present gearbox efficiencies are assumed to be constant, although the losses in these components are dependent on both speed and load. The primary target of this paper is to provide efficiency characteristics of commercially available passenger car transaxles: a 4-speed manual and a 3-speed automatic transaxle. A test-bench has been constructed in order to simulate the drive performance tests of these transaxles. The information obtained in this way reveals the performance of the transmissions in various torque-speed ranges (at full load power ratings as well as partial load conditions). Also the no load loss tests are carried out. The performance data are presented in the form of graphs, in which the plotted parameters are efficiency, torque and speed. From these results conclusions are drawn on the efficiency of both drive trains.