Design and Construction of the Steering System on the Trolley City Three-Wheeled Bicycle Considering Quasi-Dynamics

Abstract

Three-wheeled cargo or city bicycles often experience dynamic instability and risks of tipping during cornering at moderate speeds, yet conventional rigid steering mechanisms fail to accommodate lateral leaning while maintaining structural rigidity under dynamic loads. To address this gap, this study aims to design, analyze, and construct an optimized bracket for a tilting steering system on a trolley city three-wheeled bicycle considering quasi-dynamic loading conditions. Following the VDI 2221 systematic design approach, design concepts were generated and systematically evaluated through alternative functional combinations (AFK) using evaluation criteria based on structural rigidity, manufacturability, safety factor, and weight efficiency. The selected design was fabricated and evaluated using two candidate materials: ST37 structural steel and 3D-printed PLA. Structural behavior was investigated through Finite Element Analysis (FEA) in SolidWorks Simulation to assess stress distributions and safety factors under combined static and quasi-dynamic forces, followed by direct field operational testing. The results demonstrate that the ST37 steel bracket withstood a maximum operational load of 143 kg with a safety factor exceeding 1.5, maintaining structural stability and handling control during turns. In contrast, while PLA is suitable for rapid prototyping and lightweight validation, it exhibited insufficient long-term durability and lower safety margins under real cornering forces. In conclusion, integrating quasi-dynamic considerations with systematic AFK selection yields a reliable tilting steering bracket, providing critical structural and material benchmarks for developing stable urban three-wheeled vehicles.