Many people buy SUVs because of their tall body and better passability than sedans. Although most people choose two-wheel drive, some buyers choose models with four-wheel drive system, thinking that it will be easier to encounter bad road conditions. pass. But don’t think that you can go wild with four-wheel drive, because four-wheel drive is not necessarily suitable for all off-road conditions, and if you get stuck in the car, you will be criticized by your wife.
We all know that the difference between four-wheel drive and two-wheel drive is the difference between “using both hands and feet” and “walking on two legs”. But four-wheel drive also has different structures, which can be simply divided into three categories: split four-wheel drive, timely four-wheel drive and full-time four-wheel drive.
Timely four-wheel drive is just an emergency, don’t run wild everywhere
Urban SUVs with timely four-wheel drive are mostly front two-wheel drive, and the grip is the same as that of front-wheel drive cars. Although many urban SUVs now have 4WD or 4*4 signs on the rear, most of the time they are two-wheel drive. Models such as CRV, Tucson, Smart Run, etc., are all timely four-wheel drive, usually front-wheel drive, and only when the front wheels slip, will the power be transmitted to the rear wheels.
But don’t think that with four-wheel drive, you can go wild everywhere. In the face of some extreme road conditions, the timely four-wheel drive is lagging behind because of the switching, so when it starts to move, it may be too late, and the vehicle may have been stuck in the mud. Can not extricate themselves. Of course, some urban SUVs have a four-wheel drive lock mode, which can force the vehicle to be kept in a four-wheel drive state. On slippery or rough roads, this locked state makes it easier for the vehicle to obtain stronger grip and get out of trouble, but this Lock mode only works at low speeds, and off-road performance is only marginally better than regular 4WD.
The fuel consumption of full-time four-wheel drive is higher than that of timely four-wheel drive, and the off-road performance is relatively higher
Full-time four-wheel drive can improve road performance and driving performance on slippery roads, but full-time four-wheel drive without a central differential lock has limited off-road performance, because if one wheel spins, it will stop.
Models such as Subaru Forester, Acura MDX, Audi Q5, BMW X3, and Mercedes-Benz GLK are full-time four-wheel drive, which means that all four wheels are working hard at any time . Compared with the other two driving methods, full-time four-wheel drive has more advantages. Better road adaptability, now many systems can freely distribute the driving force of the front and rear axles, and even the left and right wheels can be freely distributed. Whether it is a normal road or a muddy and slippery road, it is in a four-wheel drive state, so it can provide better driving performance. , of course, its fuel consumption is relatively increased, after all, the simultaneous action of four wheels will consume more power.
In addition, full-time four-wheel drive is also commonly used in some high-performance cars. For example, Audi A4, A6, and A8 all have four-wheel drive versions, and Volkswagen’s imported Magotan, Golf R, Subaru Impreza, Nissan GT-R, etc. These models themselves or Its high-end version has full-time four-wheel drive. These models generally advocate sports, pursue high horsepower and neutral steering characteristics. Because power is distributed to four wheels, it is less likely to slip than two-wheel drive, so this type of vehicle can obtain greater grip and greater acceleration during rapid acceleration. Of course, four-wheel drive also allows them to increase their performance on slippery roads. Compared with the understeer of front-wheel drive vehicles and the oversteer characteristics of rear-wheel drive vehicles, their steering performance is more neutral, that is, where to hit, and the driving is more able to achieve the state of the car as people want.
Part-time four-wheel drive hard-core off-road representative requires a higher level of operation
Don’t say you are a hardcore off-road fan if you don’t buy a time-sharing four-wheel drive SUV.
Part-time four-wheel drive is often used by hard-core off-road vehicles. Their drive mode can be selected manually. Under normal road conditions, the rear-wheel drive mode is often used. When encountering difficult roads, the driver can connect the front wheel through the transfer case The original Beijing 212 Jeep, the current Suzuki Jimny, Mitsubishi Pajero, Toyota Land Cruiser, etc. all use this transmission mode. However, the time-sharing four-wheel drive also has subdivisions. Some models do not have a central differential, which means that the front and rear wheels are rigidly connected in the four-wheel drive state. On hard roads, when turning, there will be interference between the front and rear wheels. This leads to difficulty in steering and tire wear, so this type of model can only use four-wheel drive on off-road and slippery roads for a short time, and must be switched back to two-wheel drive mode when returning to normal road conditions.
Now , many time-sharing four-wheel drive models are equipped with a central differential , which can successfully solve such problems, and the four-wheel drive mode can be used on normal roads, even at high speeds without any problems. Off-road vehicles using this method usually have a low gear, that is, the transfer case has two high and low gears. In the low gear, the vehicle can obtain greater torque, making it easier to get out of trouble or climb a steeper slope.
Timely four-wheel drive and full-time four-wheel drive do not have a central differential lock. In the four-wheel drive state, the connection between the front and rear wheels is usually a flexible connection. In other words, when one of the four wheels leaves the ground or slips, the driving force Most of it will be transmitted to this wheel, while the other three wheels can only get very little power, resulting in slippage and car sinking. Therefore, some intelligent timely four-wheel drive or full-time systems will achieve a certain degree of “hard connection” through limited-slip differentials, forcibly combining multi-plate clutches, and electronic system control brakes to lock slipping wheels. The four-wheel drive is in the same state as the front and rear wheels to achieve good off-road performance. Of course, it depends on whether the four-wheel drive system is smart enough, because it judges the state of the vehicle, and then distributes the power through the centralized method mentioned above. And lock the wheels to achieve the effect of getting out of trouble. And this kind of model equipped with this kind of intelligent four-wheel drive system is usually relatively expensive.
Photo and text source: Chezhaocha.
