Boundary Conditions Affecting Gear Whine of a Gearbox Housing Acting as a Structural Member

Vehicle cabin gear whine levels have long been known to contribute to driver annoyance and perceptions of poor quality in passenger cars and trucks, as well as contributing to operator fatigue in helicopters and heavy machinery. For material handling vehicles, radiated gear whine not only influences annoyance and fatigue of operators, but also creates unwanted noise in the operational environment such as warehouses and plants. Upfront management of gear whine levels using predictive software tools is therefore critical for satisfactory design of gearboxes used in such applications. One challenge, however, is selecting the proper boundary conditions for modeling a gearbox acting as a load-bearing structural member used in the material handling vehicles. Boundary conditions assumptions, such as for the gearbox housing attachment locations to the chassis, can have a direct impact on the predicted housing deflections and subsequent gear mesh misalignment for a given drivetrain load, thereby affecting transmission error at the mesh location and the resulting vehicle cabin gear whine levels. Various boundary condition approaches were investigated for the virtual analysis of a material handling gearbox, predicting the resulting mesh misalignment and transmission error for each condition. Gearbox vibration levels were also examined for several configurations.