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<div class="section abstract"><div class="htmlview paragraph">The power loss of bearings is a significant factor in the overall efficiency in a drive unit system. Such bearings are subject to combined radial and axial loading needed to support the gear mesh forces. An experimental methodology has been developed to perform sets of power loss measurements on TRB, 4PCBB and DGBB. These measurements were performed under a variety of speed, load, temperature, and lubrication conditions. The loss behaviors of these types of the bearings are discussed, along with the tradeoff of different bearing arrangements for the fuel economy cycles. Several power loss models are employed to assess the accuracy of the estimations as compared to the experimental measurements. At low speed some models showed good correlations for TRB and DGBB, while at higher speed, they start deviating from the testing results. A higher fidelity model for estimating the losses at high speed, especially speed around 20krpm and beyond, needs to be developed. For 4PCBB, the models showed under prediction for the losses within the testing range.</div></div>

Power losses of load carrying gear and bearing components of automotive transmissions have become a major research area in recent years. Measurement of power loss of a gearbox is a routine task where losses from rolling element bearings, gear meshes and seals collectively define the total loss. However, separating bearing and gear mesh losses is not possible, as a gear mesh cannot be operated without support bearings. This study aims at developing a methodology for measuring power losses of rolling element bearings of different types operated under realistic load, speed and temperature conditions. A test machine concept is implemented to apply combined radial and axial loads to a pair of test bearings in a stable and repeatable manner, with rotational speed and lubrication parameters controlled tightly during tests. The proposed test methodology is employed to evaluate power loss for three different types of bearings. Load-dependent and load-independent components of power loss are separated, and influence of speed and load values on bearing mechanical loss are quantified. A repeatability study of the machine and methodology is also presented to demonstrate the accuracy of the proposed setup.