Abstract
To gain advantage in off-road racing such as the King of the Hammers racing event, racers use a 74Weld 2 gear crawler portal system. Currently, frequent failures of spur gears from the portal system occur under the extreme loading conditions of off-road racing. The goal of the current study was to identify the cause of the failure and attempt to redesign the component to reduce the failure rate. The microstructure and components surface were analyzed using light microscopy. A failed spur gear was analyzed through finite element analysis (FEA) using the SolidWorks FEA package. Five FEA models were developed to determine the baseline stress for the current design and for a component redesigned with a chamfer to determine if the maximum stress can be reduced with the new design. The material identified was close to the composition of commercially available AISI 4340 quenched and tempered (Q&T) steel. Based on the microstructural analysis, the material was eliminated as an issue for the failure. Examining surface effects, the wear on the face of the gear was not an issue for failure. Under the loading conditions of the off-road racing vehicles 1000 hp engines, the FEA predicted brittle failure based on the cracks present at the root of the gear. The FEA analysis also predicted a reduction in stress at the gear root indicating the new design was a potential solution to prevent gear failure under these harsh racing conditions.