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Recently, Volkswagen released its proud pure electric vehicle ID.4, which caused an uproar in the automobile industry headed by Tesla.

Some people think that this is a few years ago, China people lying counting money entered the mast sail of the electric blue ocean; Others think that ID.4 will become a sword for Volkswagen to kill Tesla.

Whether ID.4 can defeat Tesla or even be defeated by new domestic forces such as Weilai and Tucki is not my concern today.

Today, I will talk about something that should not be unusual: Volkswagen officially "invented" the drum rear brake again.

Where are the domestic consumers? Volkswagen ID.4 made an emergency booking immediately after its debut, but the drum brake on the rear wheel of ID.4 worried everyone.

In order to highlight the importance of the domestic market, Volkswagen naturally has to give a presentation as usual, so the senior executives of Volkswagen gave the following analysis: only the motor is enough to slow down, and most electric vehicles use the front axle for braking, and the number of brakes used is less than that of fuel vehicles.

Volkswagen conducted a survey and found that users in China only used the rear brake when braking in an emergency. The advantages of disc brake can have better braking performance in all scenarios. Drum brake inherits many advantages, and is protected by shell, which is more solid and corrosion-resistant. Moreover, the drum brake can be used until the end of the product life cycle of this car, and the maintenance cost is lower. This also shows that the drum rear braking system re-invented by Volkswagen is the most advanced braking system.

As soon as this statement came out, some netizens in Weibo jokingly expressed their strong dissatisfaction: hand-cranked windows are not only low in cost, but also less in wiring layout and high in safety. At the same time, it also saves power consumption, improves battery life and keeps healthy. It is also the most advanced window control system, which is worth recommending.

Some netizens also said not to make the restoration so fresh and refined.

People who have been deeply involved in the China market for many years may think that they are still qualified to educate the China market, but I don't agree with the above explanation.

Before expressing my opinion, let's learn about drum brakes. There are two kinds of braking methods commonly used in automobile industry: one is drum braking, and the other is called disc braking.

Drum brake can be regarded as the earliest braking system applied to vehicles, in which the brake drum is installed on the wheel and rotates with the wheel; When the vehicle is braked, the brake piston will push the brake pad outwards to generate friction with the brake drum, thus achieving the braking effect.

Drum brakes are simple in structure and low in manufacturing cost, and are often used in the braking system of rear wheels of low-end cars or large trucks.

Because of the low manufacturing cost, there will naturally be other defects. For example, the diameter of the brake drum will increase after heating, and the stroke will increase when stepping on the brake plate; The intuitive feeling is that you step deeply, but the braking effect is not obvious.

This is also the reason why people hesitate to buy ID.4 After all, this thing has long been associated with the low-end without hesitation.

The structure of disc brake is different from that of drum brake, and its braking mechanism is not encapsulated in the brake drum; By driving the initially stationary brake disc and clamping the brake disc rotating with the tire to generate friction, the wheel speed is reduced.

Therefore, the heat dissipation performance of disc brake system is much better than that of drum brake, which reduces the risk of brake failure caused by heat when braking continuously; The change of brake disc size after heating will not lead to the increase of brake pedal stroke; In addition, the disc brake system responds quickly and is suitable for high-frequency braking, so it is more in line with the requirements of ABS system.

We know that some domestic electric vehicle enterprises, in order to improve the braking effect of vehicles, began to use expensive carbon ceramic ventilation brake discs instead of cast iron brake discs on the basis of using disc brakes; Compared with this, I think the public should feel a little ashamed.

It can be said that the drum brake has basically disappeared in the automobile jungle of more than 654.38+ million; I am puzzled to put such a work with a strong sense of time on the platform of MEB. Is it because the CEO of Continental Group said "Brother, look at this epidemic, business is hard to do" when having coffee with the CEO of Volkswagen Group? . Dude, I still have some drum brakes in stock. Why don't you help me consume them? Volkswagen CEO readily said: What's so hard about this? It depends on my brother. Then let's kill two birds with one stone. (This story is pure fiction)

We need to make it clear that when driving an electric car without stepping on the accelerator pedal, the speed of the car will decrease. But is this exclusive to electric vehicles? Of course not. For a fuel car, you can also slow down by not stepping on the accelerator.

The difference is that the manual fuel truck needs to step on the clutch and shift gears when the speed decreases. For an automatic fuel car, the clutch is simply omitted. From this point, I don't see the advantages and convenience of electric vehicles in deceleration.

The only difference is that electric vehicles are generally equipped with energy recovery devices; When the car slows down, the energy recovery system will intervene, thus improving the deceleration effect of the car. However, for ID.4, the energy recovery effect is very slight when the D gear is engaged for deceleration; Unless you engage the B gear (kinetic energy recovery mode), the recovery during deceleration will be significantly enhanced and the deceleration effect will be stronger.

But how many people will stay in B gear to protect the drum brake?

We know that when using this powerful electric energy recovery function, the rear passengers will feel uncomfortable and get carsick easily; Moreover, when using the electric energy recovery device, the rear car can't see the brake signal light of the front car, which will form the illusion that the front car has no brakes, which is easy to cause rear-end collision.

In addition, Volkswagen hopes to compete with the current new energy killers. It seems that its battery life is less than 400 kilometers, so the battery life of ID.4 has reached 555 kilometers. When the battery life goes up, the weight of the battery will inevitably leap (the current battery energy density remains unchanged), which has created the self-weight of Volkswagen ID.4 of more than 2 tons; Self-importance, inertia is naturally great. It's like a fat man and a thin man with the same figure running to hug you at the same speed, and you can feel the difficulty of the fat man stopping.

In addition, the motor can only slow down at low speed, and it is inevitable that the brakes will be used frequently when encountering obstacles in front or following cars at high speed.

Therefore, in my opinion, it is untenable for Volkswagen executives to find excuses for installing drum brakes through the fact that electric vehicles use motors to slow down.

I don't quite understand this point, because when we step on the brake pedal, four wheels should brake at the same time, but the braking force of the front and rear wheels is different; It should not happen that most users only use the front axle for braking.

For the specific braking process, everyone may not be particularly clear; Let me explain in detail here that the brake pedal we step on directly controls the brake master cylinder, which is connected with the brake cylinders distributed in the wheel brakes through pipes filled with brake oil, and the braking force will also be transmitted to the four wheels through the brake oil.

In my opinion, when the car brakes, the speed of the car will decrease. At this time, under the action of inertia, the car will continue to move forward and the overall center of gravity of the car will move forward. At this time, the braking force on the rear wheel will be less than that on the front wheel, but at this time, the rear wheel will also be braked, and the rear brake will not be used when the user brakes urgently.

So I don't agree with this sentence of Volkswagen executives. I don't know if the Volkswagen executives at that time didn't express themselves clearly or let it slip.

In any case, a very obvious disadvantage of drum brake is that it is not easy to dissipate heat; Although when we use the foot brake, the braking force on the rear wheel is less than that on the front wheel, when the brake pedal is strongly depressed or the high-frequency brake is used for emergency braking, the brake is prone to thermal recession, which is not conducive to driving safety.

In this case, the public may have to put warning signs when selling cars. It is not recommended for car owners who often brake suddenly when driving to buy this car.

ID.4 of FAW-Volkswagen 550km battery life? CROZZ and SAIC Volkswagen's ID.4 have a battery life of 555 km? X's subsidized price will not exceed 250,000 yuan, so it can be seen that Volkswagen is a little different from Tesla's model in price. 3 the meaning of hard and rigid.

However, it is said that the installation of drum brakes by Volkswagen was caused by Tesla. It is estimated that Musk will feel that he is lying down. But after all, in the electric vehicle market with a price level of more than 200,000, everyone seems to have no shortage of choices; Therefore, if the public wants to step in quickly and occupy a place, they must have an advantage in price.

After all, no one wants to make money at a loss; It is imperative to control costs. Seeing that Tesla is localizing parts on a larger scale, the future selling price may be further reduced; Volkswagen has been operating in China for many years and has a mature supply chain. It is very difficult to significantly reduce the price of parts like Tesla. So the soldiers took risks and made an abacus to replace the traditional structure at a lower cost.

In any case, it takes years or even decades for a brand to be established, but its collapse is only in an instant. The influence of the China insurance research event is still fermenting, and the continuous decline in sales volume is warning the public not to make any attempt to damage the brand image.

If the public wants to win the public's favor, the better way is to replace the drum brake with a disc brake as soon as possible, and don't ruin a pot of porridge because of this mouse shit.

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