What are the types of automobile transmission systems? What are their characteristics?

1. Front and rear drive -FR: front and rear wheel drive of the engine.

This is the traditional layout. Most trucks, some cars and some buses at home and abroad adopt this type. The advantages of FR are that it is easy to get enough driving force due to its large adhesion, the weight of the whole vehicle is relatively balanced before and after, and the handling stability is good. The disadvantage is that there are many transmission parts, many transmission parts and large transmission system, and the transmission shaft running through the cabin occupies the platform space in the cabin.

2. Rear-mounted rear drive-RR: that is, rear-mounted engine and rear-wheel drive.

This arrangement is mostly used for large passenger cars, and a small number of mini-cars and light-duty cars also use this form. The rear engine makes the front axle not easy to overload and can make full use of the area of the trunk. It can also effectively reduce the height of the floor of the car body or make full use of the space under the floor in the middle of the car to place luggage, which is also conducive to reducing the influence of the high temperature and noise of the engine on the driver. The disadvantage is that the engine has poor heat dissipation conditions, and some faults during driving are not easy to be noticed by the driver. Remote control also makes the control mechanism complicated and inconvenient for maintenance and adjustment. However, due to its outstanding advantages, it is more and more used in large buses.

3. Front drive -FF: engine front, front wheel drive.

This control mechanism is simple and the engine has good heat dissipation conditions. However, when going uphill, the mass of the car moves backward, which reduces the adhesion mass of the front driving wheel and makes the driving wheel slip easily. When braking downhill, the car mass moves forward, the front wheel load is too heavy, and it is easy to roll over at high speed. Most cars adopt this arrangement.

4. Drive train of off-road vehicle

Off-road vehicles are generally all-wheel drive, the engine is front-mounted, and a transfer case is installed behind the gearbox to transmit power to each wheel. Light off-road vehicles generally adopt 4×4 drive type, while medium off-road vehicles adopt 4×4 or 6×6 drive type; Heavy off-road vehicles generally adopt 6×6 or 8×8 drive type.

5. Mid-mounted rear drive-MR: It means that the engine is mid-mounted and rear-wheel drive.

The engine is placed between the front and rear axles and driven by the rear wheels, similar to the layout of the F 1 racing car. There is also a "front center engine", that is, the engine is placed behind the front axle and in front of the passengers, which is similar to FR, but can achieve the same ideal axle load distribution as MR, thus improving maneuverability. MR has the advantages of uniform axial load distribution and neutral handling characteristics. The disadvantage is that the engine occupies the cockpit space, which reduces the space utilization and practicality, so MR is mostly a sports car that pursues handling performance.

6. Four-wheel drive -—4WD

No matter which layout above, you can use four-wheel drive. In the past, off-road vehicles were used the most. However, with the development and application of limited slip differential technology, four-wheel drive system has been able to accurately distribute torque between wheels, so high-performance sports cars are increasingly using four-wheel drive to improve maneuverability. The advantage of 4WD is that all four wheels have power, and the attach rate on the ground is the largest, with good trafficability and power.