The "front disk and rear drum" sounds like an old story, but there are still cars using it, is it safe?

In the era of bicycles with front and rear disc brakes, there are still a lot of cars sticking to the "front disc and rear drum" brake layout. I've often heard that drum brakes are unsafe, so when buying a car, should I still consider a model with "front discs and rear drums"?

Now we mention the car safety often think of seat belts, airbags, these manufacturers often publicize the configuration, but play an important role in the safety of the brake system is often ignored.

In fact, since the invention of mankind's horse-drawn carriages, there has been a braking system, but the earlier horse-drawn carriages braking system is the principle of leverage, the need for braking with a crowbar like wood to the rims of the carriages to produce friction, so as to achieve the braking effect, that's right, and we use the bike with the "soles of the shoes brakes! "

Early days

There were no brakes on early automobiles, after all, they didn't run as fast as people did, and they couldn't use the "foot brake".

But with the development of technology, the automobile can be faster than the horse-drawn carriage, but how to stop has become a big problem. Originally used in the carriage on the "sole brake" is obviously not enough, that kind of braking in the quality of light, slow carriages are still effective, put into the high-speed car on the elbow.

So, in 1900, Wilhelm Maybach designed the earliest automobile drum brakes, the current Mercedes-Benz S-class Maybach sedan, which originated from the name of this engineer. This also shows in a sense the great contribution of Wilhelm Maybach to the automobile industry (this person has made a great contribution to the development of automobiles, and it is recommended that you have time to look up information to further understand).

And almost at the same time, in 1902, British engineer Frederick William Lanchester designed and patented the automobile disc brake.

So many people often say that drum brakes have a longer history, but in fact, the invention of disc and drum brakes is not as far apart as one might think.

Only limited by the problem of metal materials at the time, the production of disc brakes wear resistance is very poor, the application is not widespread, so let the drum brakes are very popular with the basis of universal application.

But and disc brakes a situation, drum brakes also encountered a lot of setbacks in the material, due to poor heat dissipation, long-term use will produce thermal decay, resulting in the brake stability is not good, the operation is also very difficult, but the biggest benefit is still in the drive to its large number of applications - cheap.

And there was actually another important reason for the poor braking performance at the time, as mentioned in yesterday's article, early vehicles used a rear-drive structure, and the brakes were only mounted on the rear wheels, so the braking effect wasn't good, and the real four-wheel braking system wasn't invented until 1909. But the disadvantage of poor braking performance still hasn't been solved.

The development of the automobile through hundreds of years, in fact, is a complete history of human industry, due to the impact of war and other factors, the poor performance of the braking system is just so again was cobbled together for decades.

Later metal materials have made great progress, mankind will once again look to the better performance of the disc brakes, to 1939, by the Chrysler Motors Plymouth test car became the first sedan equipped with four-wheel disc brakes.

And, influenced by World War II, production didn't begin until 1950, when the Chrysler Crown Imperial also became the first production model to be equipped with four-wheel disc brakes.

Despite the huge advances in materials, the cost of disc brakes at the time was still high, with Chrysler disc brakes reportedly costing as much as $400, and the structure was different from what we see today, with friction braking between the discs and the pads, and a form of braking known as the "dual disc" brake. The brakes were a form of braking called "dual discs", which is more like the principle of "friction welding" that we often see, so the stability was not much better than drum brakes.

In the 1960s, with the continuous development of technology, the material of the brake disc from copper to cast iron to aluminum alloy, carbon ceramics, etc., the process continues to progress, durability also continues to increase, disc brakes began to slowly popular.

But until now, disc brakes and drum brakes have not won or lost the battle, but rather, they each play their own roles in the market and share the limelight. The reason for this is that their structural characteristics are inseparable.

In layman's terms, the simple distinction between drum brakes and disc brakes is that one is "closed inside" and the other is "hung out to dry".

The core component of the drum brake is a brake drum, with two semi-circular brake pads placed in the "inner circle" of the drum brake. When the brake is applied, the hydraulic piston will raise the two brake pads to open up and produce friction on the wheel wall, thus realizing the purpose of braking.

The biggest advantage of using this method is that it is low-cost and the brakes are strong, so many large cars love to use it. But it also has obvious drawbacks, because the long-term "closed" in the rim, the brake pads heat dissipation is very bad, long-term braking will produce thermal attenuation, thus reducing the braking effect.

So many large trucks have to spray cooling after long-term braking, and because of the accumulation of friction debris is difficult to exclude, in the braking force is large, easy to lead to four wheels braking strength is not uniform, once the tuning is not good is easy to produce the route after braking offset.

Additionally drum brakes in the braking, due to the traditional system is cumbersome, braking response compared to disc brakes (disc brakes) to slow down a lot. Even when equipped with a brake assist system such as EBS, it is difficult to maximize performance.

The disc brakes are better understood, like a pair of pliers pinching a piece of iron, "pliers" is the brake caliper (which has brake pads), "iron" is the brake disc.

If we talk about the advantages and disadvantages, in addition to the higher cost, basically circumvented those shortcomings of the drum brakes. At the same time, disc brakes add an unexpected advantage, which is that they make the vehicle look sleeker and better.

It is based on such characteristics that disc brakes have now begun to popularize to larger vehicles. According to the requirements of GB7258-2017, from January 1, 2020 onwards, three-axle railing plate type, warehouse grille type semi-trailer should be equipped with disc brakes. At the same time, all three-axle palletized and barn-type semi-trailers with a total mass greater than 12,000kg should be equipped with air suspension.

But then again, in trucks have begun to popularize disc brakes today, there are cars with drum brakes?

Car News searched for models that might have "front discs and rear drums," and found that there are quite a few. Joint-venture models such as the GAC Honda Fit, SAIC Volkswagen Polo, GAC Toyota YARISL ZhiXuan, and the FAW Toyota Vibe are still equipped with "front disc and rear drum" brakes.

Of course, these cars are also the pursuit of economic entry-level family car, the price is also concentrated in the price range of 7-10 million yuan, so the reason why the manufacturer is so configured or to consider the economy a little more. We do not have to worry too much, such a small car with drum brakes on the rear wheels in addition to the appearance is not so good-looking, there is a guarantee of braking performance, and car companies to reduce the cost of us to buy a car price can be lower, just don't low-cost prices have not changed, you say yes or no?

This article comes from the author of the automobile home car family number, does not represent the views of the automobile home position.