The Impact of Lubricant Viscosity and Materials on Power Losses and Efficiency of Worm Gearbox

The results of the experimental research of the power losses and efficiency of single-stage worm gearbox, which is designed for such purpose, are presented in this paper. Three worm pairs (coupled gears) ZI type with the same geometric characteristics were used in the research, where worms are made of the same material (hardened and ground steel type 42CrMo4) and worm gears are made of three different types of material (zinc-aluminium alloy ZA12, aluminium alloy A356 and tin bronze CuSn12). The main part of the research is conducted to investigate the application of new materials for the manufacturing of worm gears (alloys ZA12 and A356) and their impact on the power losses and efficiency in comparison to tin bronze CuSn12. The values of efficiency are determined for different operating modes of the gearbox, that is, for different values of input rotational speed and load, where different viscosity lubricants were used. Depending on the operating mode and measured operating temperatures, the calculation of power losses and coefficient of friction for all experimental worm pairs was performed. Based on the obtained results, it can be concluded that the best tribological characteristics has worm pair 42CrMo4/ZA12, which is the recommendation for the use of ZA alloy for manufacturing of worm gears as the alternative for tin bronze and other non-ferrous metals.