Assessment of Probability of Gear Tooth Side Wear of a Planetary Gearbox

Abstract

Gear tooth side wear in planetary gearboxes represents one of the main reasons for damage occurring in these gears. Wear magnitude is unpredictable and depends on temperature, lubrication, load, material and other random variables. Wear is a non-stationary process which is impossible to describe using a mathematical model, or to accurately assess its intensity, magnitude and distribution along the tooth sides. This paper suggests a probability assessment model for gear tooth side wear, based on experimental tests and a statistical representation of obtained results. Experimental tests of planetary gearbox gears were performed within a closed power circuit, using a previously prepared testing table, and the results of wear probability distribution were analysed. Wear probability distribution was represented using the Weibull distribution model. Obtained results of this statistical analysis have shown good compliance with the experimental ones, hence this model is applicable to all gearboxes. This method represents a considerable contribution to wear probability distribution assessment and can be used in order to assess the work life and elementary reliability of gears.

Reliability Evaluation of Transmission Planetary Gears “bottom-up” approach

“…Zero thickness of worn layer corresponds to zero probability. Since the process of surface destruction of the tooth flanks is long-lasting and gradual, the Weibull function is also extended over a large interval of the number of stress changes, i.e., the number of gear teeth [32].…”