Analytical efficiency calculation for grease lubricated worm gears

Abstract Lubricating oils are the predominant choice for lubrication in many commercially utilized worm gearboxes. However, specific requirements and environmental conditions have driven a growing demand for oil-free drive systems. In certain applications this can be achieved using lubricating greases. Substituting lubricating oil with grease, and the consequent alteration in lubricant properties, introduces new challenges in the design, analysis, and tribological characterization of these gearboxes. In this context an analytical model to determine the efficiency of grease lubricated worm gears was developed including the rheological properties of greases and the tribological description of a grease-lubricated tooth contact which helps to take advantage of greases in worm gears by predicting the friction in these applications. Experimental results from different tribometers are used to determine lubricant parameters as well as tests on worm gears to validate the model. A simulative and experimental study for various operating conditions was conducted to investigate the influence of different operating modes on the efficiency of grease lubricated worm gears.