"Full-time four-wheel drive, please don't tow", what is it?

Why is it that all-time four-wheel drive is not allowed?

Maybe sometimes when we wander around the roadside, we will see all kinds of stickers on some car bodies, some of which are funny car stickers such as "I'm shy, don't kiss me", and some of which are car stickers like internship signs. These slogans are all the ones we can understand at a glance, but some people may not understand them, such as "Full-time four-wheel drive, no towing" posted on some cars, and some people don't know what full-time four-wheel drive is. Let's explain it below.

there are many ways to drive a car, including front-wheel drive, rear-wheel drive, time-sharing drive and full-time drive.

the so-called front wheel means that the front wheel is the driving wheel, and the power is mainly output at the front wheel, while the rear wheel is the driven wheel, with no power output. In the same way, I don't think we need to explain the rear drive. Time-sharing and full-time driving are more advanced. The driving device of each wheel of full-time four-wheel drive is independent, and there is a central differential to adjust the speed difference.

part-time 4wd can have both two-wheel drive and four-wheel drive.

Two-wheel drive is equivalent to ordinary vehicles, and the owner can adjust the two-wheel drive and four-wheel drive according to the road conditions at that time. When the road conditions are good, most of them use two-wheel drive, and when the road conditions are bad, most of them use four-wheel drive, so that the power can be improved to deal with potholes. Multi-disc clutch and additional adhesive clutch are two main basic types of full-time four-wheel drive.

There are two main reasons for the car being towed away:

One is that the car can't move when it breaks down on the road, and the other is that it is forcibly towed away by the traffic police in violation of the traffic law. The way the latter towed the car was that the front wheels were lifted and the rear wheels landed, which was the biggest nemesis of full-time four-wheel drive. In this trailer mode, the rear wheel rotates on the road due to friction, but the front wheel cannot rotate because it is overhead. As we all know, the central differential is connected to the front and rear axle, and the rotation of the four wheels is controlled by it. They are all driving wheels, and this situation that only the rear wheel rotates and the front wheel does not move can easily lead to the central differential being damaged.

It's all right if the mopping time is short and the distance is not far, but if it is a long-distance trailer, the harm to the car is quite great. In this case, all four wheels should be off the ground, and the wheels should not rotate. If it is part-time 4wd, it can be used as an ordinary vehicle for towing just by adjusting it to two-wheel drive.