Abstract: In order to improve engineering vehicular efficiency, the expression of shift schedule is deduced from the function of torque converter and transmission in vehicular powertrain, and shift schedule saving energy of engineering vehicular automatic transmission is obtained. The shift schedule can maintain torque converter working in the range of a limited idealized value under all the working condition except the left low efficiency range when transmission worked in the lowest shift and the right low efficiency range when transmission worked in the highest shift. The bench-test of automatic shift adopting this shift schedule is done on automatic transmission’s test-bed. The experimental results show the shift schedule is correct. This shift schedule will improve the efficiency of hydrodynamic drive system of the vehicle.

Key words: Automatic transmission, Engineering vehicle, Hydrodynamic drive, Saving energy, Shift schedule, 3D topography, Cutting path, Gear grinding, Gear honing, Internal meshing, Mechanism