masoud tarahomi

The purpose of this paper is to optimize the gearbox conversion ratios of vehicles and the gearbox gear ratios are calculated in such a way that the engine provides the maximum possible traction, thus providing the maximum slope force with respect to the stability condition. First, the gearbox conversion ratios are determined by considering the type of vehicle and the appropriate calculation method. Then the gear conversion ratios are changed so that, considering the stability condition, the traction force diagram in the gears is as close as possible to the ideal traction force diagram and the uncovered parts are less in the ideal traction force diagram and the actual middle gear diagram. This is done for a two-stage gearbox with two intermediate axles, which is located in the transmission line with a diesel engine. The obtained results show that with the optimization of the gearbox, the rate of improvement of traction force in the maximum case is 17.5%, slope 16.3%, acceleration 17.2% and torque 13.5% in 3rd gear. Comparisons made for validation with a base vehicle also show a good agreement between the base vehicle and the vehicle in this study.