Abstract: To study the starting response of heavy-duty off-road vehicle on plateau, a full vehicle model is established using GT-SUITE. The effects of altitude, gear shifting moment of and front gear ratio on the starting-up process of heavy-duty off-road vehicle are studied through simulation. The research results show that the starting process of vehicle takes 14.7 s on plain, while it takes 27.2 s at the altitude of 4 500 m; in comparison with the gear shifting at 1 000 r/min, the response time of starting is decreased by 3.9 s at 2 000 r/min. Therefore, the vehicle starting response can be improved by shifting gear at high engine speed. With the increase in front gear ratio, acceleration increases during starting, but the vehicle speed decreases at steady state. Therefore, the starting response of vehicle can be improved by choosing an apposite front gear ratio. Due to the influence of air-fuel ratio limit, the common input characteristics of hydraulic torque converter and engine during starting are different from the common input characteristics of hydraulic torque converter corresponding to engine full load characteristics at the altitude of 4 500 m.

Key words: power machinery engineering, plateau, starting process, heavy-duty off-road vehicle, engine speed response, front gear ratio