Influence of gear loss factor on the power loss prediction

C M C G Fernandes,P M T Marques,J H O Seabra,R C Martins

doi:10.5194/ms-6-81-2015

Abstract

Abstract. In order to accurately predict the power loss generated by a meshing gear pair the gear loss factor must be properly evaluated. Several gear loss factor formulations were compared, including the author's approach. A gear loss factor calculated considering the load distribution along the path of contact was implemented. The importance of the gear loss factor in the power loss predictions was put in evidence comparing the predictions with experimental results. It was concluded that the gear loss factor is a decisive factor to accurately predict the power loss. Different formulations proposed in the literature were compared and it was shown that only few were able to yield satisfactory correlations with experimental results. The method suggested by the authors was the one that promoted the most accurate predictions.

Highlights

According to Kragelsky et al (1982) tribology is an important field in engineering which can contribute to develop more reliable and efficient mechanisms like gearboxes.According to Höhn et al (2009) the power loss in a gearbox consists of gear, bearing, seals and auxiliary losses
No-load losses are mainly related to lubricant viscosity and density as well as immersion depth of the components on a sump lubricated gearbox, but it depends on operating conditions and internal design of the gearbox casing
The results suggest that the gear loss factor presented by the authors in Eq (9), considering the rigid load distribution, present a much lower absolute error for the prediction of a mineral wind turbine gear oil power loss for with helical gears, previously published by Fernandes et al

Summary

Introduction

According to Kragelsky et al (1982) tribology is an important field in engineering which can contribute to develop more reliable and efficient mechanisms like gearboxes. According to Höhn et al (2009) the power loss in a gearbox consists of gear, bearing, seals and auxiliary losses. No-load losses are mainly related to lubricant viscosity and density as well as immersion depth of the components on a sump lubricated gearbox, but it depends on operating conditions and internal design of the gearbox casing. Rolling bearing no-load losses depend on type and size, arrangement, lubricant viscosity and immersion depth. Load dependent losses occur in the contact of the power transmitting components. Load losses depended on the transmitted torque, coefficient of friction and sliding velocity in the contact areas of the components. At nominal loads the power loss generated in a gearbox is mainly dependent of the gears load power losses, which puts in evidence the importance of the evaluation of the gear loss factor. The gear loss factor formulations will be compared with experimental results previously published by Fernandes et al (2015)

Load dependent power loss in meshing gears

Average coefficient of friction

Validation with experimental results

Conclusions