Optimization of a Manual Transmission Gear Ratios for a Small Cargo Carrier using Statistics-Based Simulation Techniques

This paper proposes a statistical design procedure to follow during the optimization of gear ratios for a 4-speed synchromesh transmission for a small cargo carrier application. The exercise starts with the simulation of a cargo vehicle using one of the commercially available simulation softwares. One of the reference vehicles has been simulated and then tested on chassis dynamometer to validate the simulation model. Further simulation model is adapted for the proposed vehicle. The first gear ratio is fixed based on the vehicle and the engine specifications to achieve gradeability requirements of the vehicle. The statistical technique of ‘design of experiments’ is used to carry out L27 experiments with 2^nd, 3^rd and 4^th gear ratio as the three parameters and the simulation results are predicted for each of these sets of gear ratios for the fuel consumption, acceleration and the emissions. The optimum gear ratio set is then subjected to the sensitivity analysis using L8 experiment to check the robustness of this design for variation in vehicle parameters.