Bolt Strength Evaluation of Tractor Rear Axle Based on Simulation Model

Abstract

An agricultural tractor is a working machine that performs various agricultural tasks, such as tillage operations, loader operations, and transportation. Such machines are exposed to various loads under diverse use conditions. When a massive load is applied during farm operation, bolts, which are among the various axle components, may fail. In this study, to prevent the failure of the rear-axle bolts of tractors, loading and stress tests were performed on such bolts considering the operating conditions of the tractor, and a simulation model was developed to predict the load applied to the bolt. The developed simulation model was validated based on the test results. Using the validated simulation model, the displacement of the rear-axle housing, tensile force, stress applied to the bolt, and bolt strength were investigated with respect to changes in the loading conditions. The simulation results confirmed that the deformation of the rear-axle bolt by the tensile load is considerably larger than that by the bending load. In addition, as the axial load increased, the load was directly applied to the tapered roller bearings and bolted joints. This finding confirmed that only a portion of the radial load and moment acts as the axial load. Finally, the safety factors for the yield strength, fatigue strength, and surface pressure of the bolt were found to be greater than 1.0 under the maximum operating load conditions of the tractor, confirming that there were no safety problems.