You can often see a lot of subaru cars on the road are posted on the rear: "all-wheel drive, no trailer".

Have you ever thought about:

Why do you want to attach no trailers?

Is it to prevent illegal stop by trailer, frighten people?

Or is it not recommended because trailers can cause vehicle failure?

What if the car breaks down and you have to tow?

In fact, the so-called "do not trailer" is not subaru, mainly because most of its models are all-wheel drive (except the BRZ of course) so why can't all-wheel drive trailer? Must trailer should how tow?

1. What exactly does the all-wheel drive mean

We have a special introduction to the classification and advantages and disadvantages of the four-wheel drive before. If you need to review, please click this link: is it necessary to have four-wheel drive? What kind of four-wheel drive is good? About the four wheel drive, this is the most comprehensive, the most understandable article!

Here we briefly describe the basic principle of the all-wheel drive and the just-in-time wheel drive.

First look at the general principle of timely four-wheel drive, with the multi-disc clutch central differential as an example: if a wheel slip, the electronic control system control hydraulic mechanism to press the multi-disc clutch, contact the active disc, driven disc, torque from the active disc to the driven disc, so as to achieve four-wheel drive.

That is to say, timely four-wheel drive is normally a two-wheel drive mode, when needed to convert to four-wheel drive.

The all-wheel drive has always been in the form of a four-wheel drive. When there is no need to extricate the active disk and driven disk slightly combined, the torque distribution ratio of front and rear wheels is about 95% : 5%, which can be roughly considered as an approximate precursor.

Once the speed difference is detected, that is, there is wheel slip, the multi-plate clutch changes the degree of combination quickly, which can realize the four-wheel drive in a very short time.

Here the trailer refers to the lift trailer, that is, two wheels fixed, the other two wheels on the ground sliding. The way of lift trailer is bound to make two wheels turn, the other two wheels do not turn, at this point can be understood as two wheels in the slip, to meet the speed difference, the need to extricate.

At this point, the multi-plate clutch quickly increased the degree of integration, but the trailer is not possible "out of the trap", so the possible outcome is that the central differential produced a lot of heat, leading to the central differential burn.

The above is a multi-plate clutch, such as audi's towson differential will occur the same consequences, but burned the worm gear and so on.

2, full time drive how to correct trailer

The correct way to trailer is a flatbed trailer, which means all four wheels don't touch the ground. But very short distance and very short time lift is no problem, such as lift on the cart impact is not big.

Only the subaru has a yellow "do not tow" sticker on its rear, but virtually all all-wheel-drive vehicles should take note. For example, the audi Q5, audi Q7, Benz GLE, Benz GLS and other models are all equipped with full-time four-wheel-drive, and also cannot use lift trailer.

When you buy a subaru, 4S will give you this yellow sticker as a gift. If you don't, you can ask the 4S store for one. Certainly some treasure also can buy a few dollars. If you're worried about your car being "towed away" in an unfriendly way, you can buy a sticker.

3, automatic transmission model how to correct the trailer

In addition to all-wheel-drive models, there are different opinions about the trailer of automatic transmission models. When the automatic transmission model needs a trailer, the gear should be switched to N. N block trailer, also want to ensure that the drive wheel as far as possible do not rotate, such as the front car: the front wheel to be lifted.

Because the engine is not working, the gearbox oil pump can not provide oil to the clutch friction plate, gear, etc., so it will lead to serious wear.

As for how to switch from P to N gear when the engine doesn't work, just press the button that has the unlock button. If there is no button, there must be a small rectangular hole in the platform next to the handle that can be "poked in" with a mechanical key. The effect of poking the hole is the same as the effect of unlocking the button, which can be pushed to N.

Summary: nowadays, many law enforcement trailers are not very dedicated. The owner revealed that the owner was following the trailer and his car fell off the lift plate twice. The trailer still continues to tow like this. So be sure to check your car carefully after being towed.