The arrangement of the transmission system

The common arrangement of automobile transmission system is mainly related to the position of engine and the driving form of automobile.
The arrangement of automobile transmission system can be divided into the following five categories:

1. Front and rear drive (FR)

Front and rear drive is the full name of engine front and rear wheel drive, which is a more traditional driving form. The front wheel is responsible for steering, and the rear wheel is responsible for driving the whole vehicle. In this form of drive, all the power output from the engine is transferred to the rear drive axle, which drives the rear wheels to move the car forward. Toyota Reiz is a typical front and rear drive layout.

2. Front front drive (FF)

Front - front drive is the full name of engine front - front - wheel drive, front - front - front drive is a modern small and medium - sized vehicles commonly used layout.

The front-front-drive features reduced carriage floor, significant understeer in handling, and better sideslip resistance than the FR.

The disadvantages of front drive are: driving wheel adhesion will decrease when uphill; The front wheel, as a result of driving and steering, leads to complex structure and poor working conditions.

3. Medium rear drive (MR)

The full name of middle rear drive is engine middle rear wheel drive, the engine is placed between the front and rear axles, at the same time using rear wheel drive, similar to F1 car layout form. There is also a "front mid engine" where the engine is placed behind the front axle and in front of the crew, similar to the FR but achieving the same ideal axle load distribution as the MR For improved handling.

The advantages of the middle rear drive are: the shaft load distribution is uniform, with a very neutral control characteristics.

The disadvantage of mid-rear-drive is that the engine takes up space in the cockpit, which reduces space utilization and practicality. Therefore, MR Mostly pursues sports cars with handling performance, such as Porsche.

4. Rear rear drive (RR)

The full name for REar-rear-wheel drive is Engine rear-rear-wheel drive. In the early days, it is widely used in miniature cars, and now it is used in buses, and cars are rarely used.

The advantages of a rear-rear drive are that it is compact, without a heavy drive shaft or a complex steering/driving structure for the front wheels.

The disadvantage of rear-rear drive is that the rear axle load is large, which will produce the over-steering tendency contrary to the FF in terms of controllability. As a result, this arrangement is reserved for high-performance sports cars, such as the Porsche 911 carrera, that specialize in tail-tossing.

5. Four wheel drive (4WD)

The so-called four-wheel drive, refers to the car front and rear wheels have power, according to the driving road state and the engine output torque according to different proportions of all the wheels before and after, in order to improve the car's driving ability. Generally, it is expressed by 4×4 or 4WD. If a car is marked with the above words, it means that the car has the function of four-wheel drive. Four-wheel drive is commonly used in off-road vehicles, SUVs, and now many sedans and luxury sports cars also adopt this configuration.

The salient feature of the four - wheel drive system is the transfer. Meanwhile, according to the distribution of four-wheel driving force, four-wheel drive can be divided into time-shared four-wheel drive, all-time four-wheel drive and timely drive.