Comparison of advantages and disadvantages between two-wheel drive and four-wheel drive

I won't go into details about the concept of car driving. Let me put it simply:

Front wheel drive and rear wheel drive: that is, only the front wheel or rear wheel of the car can receive power and make the wheels rotate, so that the car can move forward or backward.

Four-wheel drive: that is, all four wheels of the vehicle can receive power to make the wheels rotate and make the vehicle move forward or backward.

Advantages of front wheel drive

1. Increase the internal vacancy: the front drive has no transmission shaft, so the vacant space is more utilized.

2. Low cost and high efficiency: few and concentrated parts, direct power transmission, reducing loss and improving operation efficiency.

3. Weight reduction: the mechanical parts of the front drive are few and simple, which can reduce a lot of weight.

Disadvantaged

1. Poor handling: Because the main components such as engine and drive system are concentrated in the front of the vehicle, the rear counterweight is light, and the rear wheels are easy to lose grip, especially on wet roads.

2. Understeering: Because the front wheel has both steering and driving functions, there is an inherent problem of understeering, especially when turning at high speed.

3. Excessive load on the front axle affects comfort: the front wheel of the front drive is responsible for both driving and steering. Because the front counterweight of the vehicle is large, the front wheel is seriously worn, the front axle is overloaded when accelerating or braking, and the phenomenon of raising the head and nodding is obvious, which affects the ride comfort.

Advantages of rear wheel drive

1. Good handling: the rear wheel is responsible for driving, and the front wheel can concentrate on steering, so the vehicle is more agile when steering.

2. Good starting acceleration performance and high comfort: when the vehicle starts, accelerates or climbs automatically, the center of gravity moves backward, and the rear wheel is used as the driving wheel to enhance the grip, which is beneficial to the vehicle starting, accelerating or climbing, and provides better driving stability and comfort;

3. Convenient maintenance: the layout of control mechanism and the structure of steering mechanism are simplified, which is convenient for vehicle maintenance and repair.

Disadvantaged

1. The cost is high, and the empty room is inconvenient to use: there are many rear wheel drive parts, the assembly is complicated, and the production cost is relatively high.

2. insufficient traction and oversteer: when the rear wheel drive turns, the grip of the rear wheel is reduced due to the forward deceleration, which easily leads to oversteer, which is called "tail flick"

3. Large power loss: Because the power generated by the engine can only be transmitted to the driving wheels through the transmission shaft, the power loss is bound to be greater than that of the predecessor. Generally speaking, the waste oil of the rear drive is more than that of the precursor.

Advantages of full-time four-wheel drive

Full-time four-wheel drive is the transmission mode with the highest turning limit in expressway, which can realize that each wheel can be allocated the best driving force when the vehicle turns at high speed. Therefore, this technology is adopted by a large number of large-displacement vehicles that emphasize handling performance. The main purpose of assembling them is to improve the effective driving force and cornering limit.

Disadvantaged

Full-time four-wheel drive has complex structure, high cost and large space, and is not suitable for assembly on vehicles with low positioning or small volume. At the same time, full-time four-wheel drive consumes power, and the transmission efficiency is lower than that of two-wheel drive. For vehicles that value economy and have low engine power, full-time four-wheel drive is not suitable for assembly.

Advantages of part-time four-wheel drive

Part-time four-wheel drive technology is mature, with simple structure and good reliability. In addition, there is no need to equip a central differential lock, and the cost is much lower than that of a full-time four-wheel drive. When driving normally, it is more economical and flexible to adopt the two-wheel drive mode. In the case of bad road conditions, four-wheel drive can improve the passability of cars.

Disadvantaged

Part-time 4wd is of little significance to expressway, and it requires high driving skills. Because part-time four-wheel drive connection is equivalent to hard shaft connection, you need to be very cautious when using four-wheel drive mode. Never use four-wheel drive mode when turning on expressway. Four-wheel drive mode cannot be used when turning in sand, rain, snow and ice.

Advantages of timely four-wheel drive

The structure of timely four-wheel drive is much simpler than that of full-time four-wheel drive, which can not only effectively reduce the cost, but also help to reduce the weight of the whole vehicle. The front drive platform suitable for the front transverse engine makes it possible for many SUVs or four-wheel drive models based on this platform to be equipped with four-wheel drive systems.

Disadvantaged

At present, most of the timely four-wheel drive power of front and rear axles will be subject to the defects of the structure itself, and more than 50% of the power cannot be transmitted to the rear axle, which makes its adjustability in active safety control worse than that of full-time four-wheel drive.

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