1：What is it?
A transmission that changes the vehicle's speed by utilizing different gear ratios is called a fixed gear ratio transmission, which is also a type of electric vehicle transmission.
2：Principle
Based on a known transmission body, bearings, and various standard components, a motor flange is installed between the motor and the transmission, connecting them as a single unit. The motor's output shaft directly inserts into a connecting sleeve inside the transmission, transmitting power to one of the transmission's shafts. The gear on this shaft meshes with a passive gear on the differential housing, driving the passive gear to rotate the differential and the wheels, completing the power transmission.
3：Pros and Cons
By using this transmission, power is directly transmitted from the motor to the transmission, which then directly transfers power to the two wheels, reducing power loss. It also has advantages such as a simple structure, ease of production, and low manufacturing costs.
4：Electric vehicle development in the history of automobiles has taken only a small step. Currently, most electric vehicles use a single-stage transmission, which achieves performance similar to regular internal combustion engine vehicles through compact matching structures. It remains in one gear, covering the range from start to the vehicle's maximum speed. This is akin to driving a gasoline vehicle in first gear without shifting until the engine reaches the redline, resulting in reduced power when accelerating as the engine cannot return to the optimal torque output range. This makes the vehicle's acceleration in the middle and later stages feel strained. Currently, we have not seen the existence of multi-stage transmissions in pure electric vehicles. In plug-in hybrid models, BMW has taken the lead in equipping a compact "two-stage" transmission for the front-wheel electric motor. It is believed that the future application of multi-stage transmissions in pure electric vehicles will bring significant progress to the development of electric vehicles.
