Research Topic

Short Title	Efficiency test
Start of Project	Q4/2025
Funding	FVA-Nr. 345/III, IGF-Nr. 01IF24400N Federal Ministry for Economic Affairs and Energy, BMWE
Contact	Dr.-Ing. T. Lohner

Project Description

The total power loss of a gearbox is significantly influenced by the load-dependent gear power loss, which is determined by the friction conditions in the gears. With the FVA 345 I method, the current state of the art offers an established procedure for determining mean gear coefficients of friction and for comparing the friction behavior of lubricating oils on the FZG efficiency test rig. By covering all lubrication conditions in the test sequence, the results provide the basis for deriving tribosystemspecific model parameters for the Doleschel approach to accurately calculate the mean gear coefficient of friction.

Due to the increasing use of low-viscosity lubricating oils, the lubrication conditions are shifting towards boundary lubrication, so that the friction behavior is increasingly determined by the interaction of the lubricant and the additives with the surface and less by the base oil. As a result, there are sometimes insufficient operating points for full-film lubrication and no model parameters can be derived. Due to the increasing formulation of ever more efficient lubricants, the influence of the load-dependent bearing power loss calculated according to SKF94 in the derivation of the mean gear friction coefficient is increasing. In-situ measurement of the bearing power loss offers great potential for improving accuracy.

The aim of the research project is to extend the efficiency test according to FVA 345 I with regard to the reliable evaluation of very low-viscosity lubricants and to improve the absolute accuracy by measuring the bearing power loss in situ. In addition, a proposal for the introduction of energy efficiency classes will be developed. An extended test specification based on FVA 345 I will be formulated.