Investigation of the heavy duty truck gear drive failure

Abstract

For heavy vehicle systems, within the power transmission chain from the driving machine to the working components (wheels), gears have a large share of application in the form of gearboxes, differentials and speed reducers. Their purpose is to achieve the highest possible output torque at the working components. In one heavy-duty truck, the gearbox lost its working capacity due to the failure of its vital parts: a tapered roller bearing and a helical gear. The analysis presented in this paper, conducted on the basis of experimental and analytical methods, showed that, due to inadequate installation of the bearings’ outer ring in the gearbox housing in one intermediate shaft support, the roller bearing performed its elementary function in very unfavorable working conditions of mechanical and thermal nature. Due to the damage accumulation, the roller bearing gradually lost its working capacity. As a result, the intensity of the working conditions of the entire gearbox increased. At the moment when they reached the critical value from the aspect of the gear teeth bending strength, volumetric destruction occurred, i.e fracture of the helical gear tooth, and thus the cessation of gearbox power transmission.