The torque transmitted by the engine through the drive train is received, and the traction is generated by the driving wheels. Transmit and bear the reaction force and torque of the road surface acting on the wheels. There are 5 driving modes of imported car driving wheels, namely FF, FR, MR, RR, and 4WD. In addition to 4WD (four-wheel drive), the other 4 types (two-wheel drive) are represented by 2 capital letters. The first letter indicates the installation location of the engine; the second letter indicates the imported drive wheel. The front F means the front of the engine (FRONT), M means the middle, the engine is in the middle of the front and rear wheels (MIDPOINT), and R means the rear of the engine. If the capital letter at the back is F, it means front-wheel drive, and R means rear-wheel drive. The following briefly introduces the two-wheel drive of imported drive wheels: In the two-wheel drive form, it can be subdivided into front-rear drive (FR) and front-front drive (FF) according to the position of the engine in the vehicle and the position of the imported drive wheels. , Rear-mounted rear drive (RR), mid-mounted rear drive (MR) and other forms. 1. Front-rear-drive FR with imported driving wheels: that is, front-engine and rear-wheel drive. This is a traditional engine arrangement and driving method. The front wheels are responsible for steering, and the rear wheels are used to drive the entire vehicle. In this driving form of imported driving wheels, all the power output by the engine is transmitted to the rear drive axle, which drives the rear wheels to make the car move forward. That is to say, in actual movement, the rear wheels 'push' the front wheels to drive the vehicle forward. 2. Front-front-drive FF with imported driving wheels: that is, front-engine, front-wheel drive. This is a driving form that only appeared in the late 1970s. Most cars now use this method. It moves everything after the transmission forward. The transmission is integrated with the drive axle, and it is fixed next to the engine to directly transmit the power to the front wheels. The front wheels take on the two important tasks of steering and driving, and the long drive shaft is omitted. , Shortening the distance of power transmission, reducing power transmission loss and correspondingly save fuel. 3. Rear-mounted rear-wheel drive RR with imported driving wheels: that is, the engine is rear-mounted and rear-wheel drive. This arrangement is mostly used in large passenger cars, and a small number of miniature and light cars also use this form. 4. Mid-mounted rear drive MR with imported drive wheels: the engine is placed between the front and rear axles and driven by the rear wheels. This driving method of imported driving wheels is only used in some high-performance sports cars, which is hard to see on ordinary cars. The characteristic of MR is that the inertial heavy engine in the vehicle is placed in the middle of the car, so that the sports characteristics that the car can obtain, due to the weight distribution of the MR car's body can achieve an ideal balance.