The lithium electric vehicle internal rotor motor features three step gears that synchronously transmit torque. Theoretically, the upper straight teeth and lower helical teeth of these three step gears must be perfectly synchronized to ensure uniform force distribution and effective torque transmission.

The innovative step gears utilize straight teeth on the upper section, processed through insertion, while the lower section features helical teeth processed through hobbing. Since each gear requires two machining processes, achieving perfect synchronization is impossible, necessitating a manual selection approach. "Synchronized teeth" are designated as "assembly positioning teeth," which are marked with a black dot for later alignment during assembly.

The step gears employ injection-molded teeth, with both the straight and helical teeth formed simultaneously in perfect synchronization. Installation is based on the alignment arrows on the helical teeth, ensuring that all three gears operate in absolute synchronization during motor operation, resulting in uniform force distribution. This significantly enhances the motor's lifespan while increasing the gear modulus design, effectively addressing the gear breakage issues commonly encountered in the current market for lithium electric vehicle motors.