The electric four-wheeled vehicle production line refers to the automated assembly line used for the production of electric four-wheeled vehicles. The assembly line for electric four-wheeled vehicles typically includes the following main steps: 1. Frame Assembly: Assemble the frame parts of the electric four-wheeled vehicle, including the front and rear axles and the main chassis. 

2. Motor Installation: Install the motor and related transmission devices of the electric four-wheeled vehicle to ensure the normal operation of the electric system. 

3. Battery Pack Installation: Install the battery pack of the electric four-wheeled vehicle in the designated location, which can be done using automated robotic arms or manually. 

4. Control System Installation: Install the mainboard, sensors, and other related components of the control system to ensure the vehicle's stability and safety. 

5. Wiring Harness Assembly: Route and connect various electric wires and connectors to ensure the circuit is smooth and signals are transmitted correctly. 6. Body Assembly: Assemble the outer shell, lights, glass, etc., of the vehicle to ensure the integrity of its appearance.