Now, when we talk about car safety, we often think of seat belts and airbags, but the braking system that plays an important role in safety is often ignored by us.
In fact, since the invention of the carriage, there has been a braking system, but the earlier carriage braking system used the lever principle. When braking, use crowbar-shaped wood to rub the edge of the carriage, so as to achieve the braking effect. Yes, it has the same effect as "sole braking" when riding a bicycle.
In fact, early cars didn't have brakes. After all, none of them can run fast, so they use the "foot brake" if they really can't.
But with the development of technology, cars can already be faster than carriages, but how to stop has become a big problem. The original "sole brake" used in the carriage is obviously not enough. That kind of braking method is effective in the slow carriage, and it is stretched to the limit in the high-speed carriage.
Therefore, in 1900, wilhelm maybach designed the earliest drum brake for automobiles, and the current Mercedes-Benz S-Class Maibakh sedan was named after this engineer. In a sense, this also shows wilhelm maybach's great contribution to the automobile industry (this person has made great contributions to the development of automobiles, so I suggest you have time to look up information to learn more).
And almost at the same time of 1902, the British engineer Frederick William Lanchester designed the automobile disc brake and applied for a patent.
So many people often say that drum brakes have a longer history, but they are not. The invention time of disc brake and drum brake is not as far as expected.
However, due to the problems of metal materials at that time, the disc brakes produced had poor wear resistance and were not widely used, which made the drum brakes popular and had the basis for universal application.
However, like disc brakes, drum brakes have encountered many setbacks in terms of materials. Due to poor heat dissipation, thermal attenuation will occur after long-term use, resulting in poor brake stability and very difficult operation, but the biggest advantage is to promote its wide application-cheap.
Moreover, there was actually an important reason for the poor braking performance at that time. Yesterday's article mentioned that the early vehicles used rear-drive structure, and the brakes were only installed on the rear wheels, so the braking effect was not good. The real four-wheel braking system was not invented until 1909. However, the shortcoming of poor braking performance still cannot be solved.
After hundreds of years of development, the automobile is actually a complete history of human industry. Due to the influence of war and other factors, the brake system with poor performance has been used for decades.
Later, metal materials made great progress, and people once again turned their attention to disc brakes with better performance. By 1939, the Plymouth test car produced by Chrysler became the first car equipped with four-wheel disc brakes.
Influenced by World War II, it was not until 1950 that mass production began, and Chrysler Crown Empire became the first mass production model with four-wheel disc brakes.
Although great progress has been made in materials, the cost of disc brakes at that time was still very high. It is said that the price of Chrysler disc brakes at that time was as high as 400 dollars, and the structure was different from what we see now. What we are seeing now is the friction braking between the brake disc and the brake pad. At that time, a kind of braking form called "double disc" was adopted, which is more like the principle of "friction welding" that we often see, so the stability is not much better than that of the drum brake.
In 1960s, with the continuous development of technology, the materials of brake discs ranged from copper to cast iron to aluminum alloy and carbon ceramics. With the continuous improvement of technology and durability, disc brakes have become popular.
But until now, the disc brake and drum brake have not decided the outcome, but they have their own duties and are equally divided in the market. The reason is inseparable from their structural characteristics.
Generally speaking, the simple difference between drum brake and disc brake is an "inner seal" and an "outer suspension".
The core component of the drum brake is the brake drum, in which two semicircular brake pads are placed on the "inner ring" of the drum brake. When braking, the hydraulic piston expands the two brake pads and generates friction with the wheel wall, thus achieving the purpose of braking.
The biggest advantage of this method is low cost and strong braking, so many large cars love to use it. However, it also has obvious shortcomings, because it is not good for the brake pad to be locked in the rim for a long time to dissipate heat, and the heat will be attenuated when braking for a long time, which will reduce the braking effect.
Therefore, many large trucks need to be sprayed to cool down after braking for a long time, and because the accumulated friction debris is difficult to remove, when the braking force is large, it is easy to cause uneven braking force of four wheels. Once the training is not good, it is easy to cause route deviation after braking.
In addition, due to the complexity of the traditional system, the braking response of drum brake is much slower than that of disc brake. Even if equipped with EBS and other brake assist systems, it is difficult to maximize efficiency.
Disc brake is easy to understand, just like a pair of pliers with an iron plate. "Pliers" are brake calipers (with brake pads inside) and "iron plates" are brake discs.
When it comes to advantages and disadvantages, except the high cost, it basically avoids the shortcomings of drum braking. At the same time, the disc brake also adds an unexpected benefit, which is to make the vehicle look more fashionable and beautiful.
It is based on this feature that disc brakes began to spread to larger cars. According to the requirements of GB7258-20 17, from 2020 onwards, three-axle track and barn semi-trailers should be equipped with disc brakes. At the same time, all three-axle track semi-trailers and storage semi-trailers with total mass greater than 12000kg should be equipped with air suspension.
But then again, today when trucks have begun to popularize disc brakes, is there a drum brake car?
The car smell searched for models that may have "front disc and rear drum". After checking, I found quite a few. Joint venture vehicles such as Guangqi Honda Fit, SAIC Volkswagen -Polo, GAC Toyota-yaris Zhixuan and FAW Toyota VIOS are still equipped with "front disc and rear drum" brakes.
Of course, these cars are also entry-level family cars that pursue economy, and the prices are mostly concentrated in the price range of 7-65,438+10,000 yuan. Therefore, the reason why manufacturers configure this way is to consider economy more. You need not worry too much. The rear wheel of such a small car uses drum brakes, which is not so beautiful in appearance and has guaranteed braking performance. Moreover, car companies have reduced costs and the price of buying a car can be lower. Just don't reduce the cost, but the price hasn't changed. Do you think so?
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.