Experimental simulation of gear contact along the line of action

Abstract

In highly loaded gears, lubricated rolling/sliding contact conditions change greatly along the line of action. This leads to variation in gear frictional properties and to failures such as pitting and scuffing that take place in different positions along the tooth flank. Information on instant contact behavior is therefore very useful, but this kind of measurement in real gears is extremely complicated. Single spur gear geometry has been simulated at 38 steady-state measuring points along the line of action using a twin-disc test device focusing on the friction coefficient and on temperature and lubrication conditions. Twin-disc simulations were adjusted to match real gear experiments by using similar maximum Hertzian pressure and surface velocities. The results show that the curve shapes for the mean friction coefficient as a function of pitch line velocity are similar to the corresponding experimental results with real gears. Further, the calculated thermal Λ-values of real gears and the measured mean contact resistance correspond well. This approach shows potential for simulating gear friction and failure mechanisms along the line of action.