Computing Gear Sliding Losses

ABSTRACT

Accurately predicting frictional losses is critical for increasing gearbox efficiency. Whereas several empirical algorithms are available for numerically predicting coefficient of friction and gear sliding losses, a systematic evaluation of these is necessary to establish their accuracy and range of applicability. This paper evaluates nine different algorithms available in the literature for determining coefficient of friction and calculating gear sliding loss, and their applicability to commercial vehicle transmissions. Power loss results are compared initially to the experimental data from a standard FZG gear set, and then to two transmissions with helical gears for a range of operating torque, speed, and temperature. The differences between predictions and measurements are discussed for each algorithm evaluated and a recommendation is presented for improved accuracy within the application range investigated. The findings of this study might help gear engineers select the appropriate algorithm for calculating gear sliding losses, and ultimately increase gearbox efficiency.