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Up to now, during the automatic shift, the throttle opening of the engine usually has maintained a constant. But due to the sudden change of the gear ratio in shift process, the pull and the acceleration of the vehicle are also changed rapidly, which results in the reduction of vehicle performances and deterioration of shift qualities. For mechanical automatic transmission with non-power shift this problem becomes more serious. This paper brings forward some countermeasures to solve this problem, i.e., adjusting the throttle opening in shift process, using dynamical closed loop control, the speed difference between the synchronized gears in gearbox and the speed difference between the driving and the driven plates of the clutch can be reduced; and using sequence feedback control, the engine, the clutch and the gearbox will get the optimum matching by which the vehicle performances can be increased.

An automated mechanical transmission controlled by an optimized dynamic 3-parameter gear-shift schedule, which makes maximum use of the power-train potential and meets well with the optimal driving conditions of the vehicle, is developed in this paper. Two methods to calculate the 3-parameter controlled shift schedule are introduced-one of which is of graphic, and the other, of analytic. For the latter, the mathematical model of shift as well as an actual computer program is given, which is very accurate and convenient for use with the computer. To make full benefit of the 3-parameter-controlled shift schdule in getting better fuel economy, dynamic performance and favorable riding comfort, the throttle angle should be changed during shift which, too, is a break through when comparing with the constant throttle angle now used all over the world.