What are the advantages of four-wheel drive in rainy and snowy weather?

As we all know, cars can be divided into two-wheel drive and four-wheel drive according to the driving mode. Generally speaking, four-wheel drive vehicles are installed in SUVs or high-end vehicles, and more complex systems also bring stronger performance to vehicles to cope with more complex road conditions. So, what four-wheel drive systems are there? What are the advantages of four-wheel drive vehicles in dealing with complex road conditions such as rain, snow and slippery?

First of all, in terms of types, the four-wheel drive systems currently on the market are mainly divided into three categories: full-time four-wheel drive, part-time four-wheel drive and timely four-wheel drive. Full-time four-wheel drive, as its name implies, is that under any circumstances, the four wheels always have power output, and the handling is the best. Part-time four-wheel drive is to manually switch the four-wheel drive mode by parking, which is mostly used for some hard-core off-road vehicles, mostly hard-linked, and has high operational requirements. Timely four-wheel drive is to automatically distribute the torque of the front and rear wheels according to the road conditions through the driving computer and switch between two-wheel drive and four-wheel drive.

Although these three types of four-wheel drive have different costs, different application scopes and different strengths, they correspond to the needs of vehicles at different price points and different levels. In the current passenger car market, timely four-wheel drive firmly occupies the market of small and medium-sized SUVs with its advantages of simple operation, small occupation space and low cost, and is more suitable for vehicles driving on urban roads and light off-road sections. However, due to its structural defects, it can only transmit 25%~40% of the power to the rear wheels, and more than 50% of the power cannot be transmitted to the rear wheels, so it has a weak ability to get out of trouble under extremely bad road conditions. In this case, the hard-wired part-time 4wd has better reliability and ability to get rid of difficulties. As for the full-time four-wheel drive system, although it is excellent in maneuverability and difficulty relief, its application is limited to high-end cars because of its high fuel consumption and maintenance cost.

Of course, these three four-wheel drive systems have absolute advantages in driving safety compared with two-wheel drive vehicles (front drive and rear drive). Especially in the northern winter, the snowfall is large and it is easy to freeze; There are many rainstorms in the southern coastal areas, and the tires are easy to slip when vehicles drive on icy roads and wet roads. Once the driving wheel slips and the direction is out of control, the driven wheel can't adjust the direction, so it can only follow the side slip or tail flick, causing traffic accidents. It's like climbing a mountain and encountering a steep hillside, and you need hands and feet to stabilize your body. In addition, four-wheel drive vehicles also have better ability to get out of trouble, not only on rainy and snowy roads, but also on off-road and desert sections. When a tire gets stuck in the mud, the vehicle will automatically lock the trapped tire and distribute power to other tires, thus getting out of trouble.

Accordingly, vehicles with four-wheel drive system have higher fuel consumption and maintenance costs than vehicles with two-wheel drive system. Taking timely four-wheel drive as an example, the oil of the four-wheel drive system needs to be replaced. The limited slip differential oil and rear axle gear oil need to be replaced every 40,000 ~ 60,000 kilometers on average. But it is more important to save your life in bad weather than the extra hundreds of dollars. Take the well-known four-wheel drive system Audi Quattro as an example. The system adopts a Tolson central differential. When the vehicle skids in the snowy road conditions in the north and the rainy coastal and mountainous areas in the south, the central differential will immediately reduce the torque distribution to the front wheels, so that more driving force will be continuously transmitted to the rear wheels, which will push the vehicle forward. Therefore, for users living in the rainy coastal areas and mountainous areas in the north, four-wheel drive is more conducive to driving safety.

This article comes from car home, the author of the car manufacturer, and does not represent car home's position.