Design Optimization and Methodology for Safe Wheel End Joint

Threaded joints are considered the most basic of components. Although in use for over a century, significant problems still exist with their usage. Wheel bolt loosening in overloaded segments such as HD tippers and high-speed intercity buses poses a safety challenge for drivers, passengers, and pedestrians. Wheel nut loosening is a notable cause of service, fretting, and cracks in the mating components; contributing a significant chunk of warranty cost to the company. The need of the hour is to reinforce these joints while keeping resources at bay. This paper establishes a methodology for the evaluation and design of a safe wheel bolt joint interface including key parameters such as embedding, axial forces, and shear forces. It is necessary to obtain the minimum preload requirement for a wheel bolt joint to hold the clamped surfaces intact, which if not maintained otherwise would cause relative movement, play, shear load onto the bolt, and eventually failure. For physically auditing the pre-load the “on-off-on tightness checking method” has been incorporated. The study shows a significant increase in pre-load in geomate-coated nuts (M22X2.5 10.9 grade nuts binding rim, drum, and hub having PCD 335 mm) via optimizing the fastener finish and internal profile. A risk assessment study has been done involving bolt-nut grades, bearing stress, and thread stripping. Proof of concept has been established, verified for feasibility, and implemented in HD tippers. This approach saves any cost impact, development time, or changes in service operations, all being crucial to the industry. This proves to be a frugal and efficient way of strengthening bolted joints without disturbing size, PCD, or grade while maintaining modularity across platforms.