Home GADGETS How the increasing popularity of electric vehicles led to the revival of drum brakes

How the increasing popularity of electric vehicles led to the revival of drum brakes



Drum brakes are an OG technology that has been around for almost as long as a car. This brake was first developed in 1899 and can be found in some of the earliest car prototypes made by Wilhelm Maybach and Louis Renault et al. Drum brakes are only slightly younger than their disc alternatives. In view of their good performance and low production costs, they have long been a standard means of slowing vehicles. But in the mid-1960s, when short-brake disc brake systems became commonplace, they became unpopular with automakers. Today, it is most common in medium to heavy trucks and buses. Due to the increasing popularity of electric vehicles, drum brakes are expected to make a comeback.

The operation of drums and discs is very different, and each system has its own advantages. Disc brakes work in the same way as on bicycles: a pair of brake pads connected to the caliper squeeze the rim down to create friction and slow the rotation of the wheel. In the case of car brakes, it is a dedicated metal plate (hence the disc) rather than the rim itself. The disc system is more powerful than the drum and stops faster. This is very necessary, because compared to the rear brake, the front brake will carry 60% to 80% of the momentum of the decelerating vehicle. This is why you can hardly find The cause of the drum of the car was. Discs are also self-adjusting, which results in fewer grabs or pulls, and self-cleaning, which makes them quieter. They are also less prone to deformation due to prolonged exposure to high temperatures, and will not fade under severe braking conditions such as prolonged downhill.

Instead, the drum’s brake shoes are located in a cylindrical tank, which rotates with the rest of the wheel, and uses pistons to press the two brake shoes outward, wedging them into the inner wall of the drum to create friction. The vehicle slows down. Due to the larger surface area inside the cylinder, the drum shoes can be made much larger than the brake disc of the brake disc, which makes them have a longer service life and exerts more force than the brake disc on the brake disc of similar size. Greater braking force. More importantly, because the drums are located farther in the wheel assembly, they can easily be used as parking or emergency brakes, while vehicles with four-wheel discs need to add a separate electronic brake.

In the latest generation of electric vehicles, drum brakes actually make a lot of sense.Take the public New ID. 4 with Coming ID.3 Take electric cars as an example. The rear wheels of both models use drum brakes designed by Continental. “Drum brakes are designed with no residual braking resistance,” a spokesperson for Volkswagen’s electric vehicle testing team in North America told Engadget. “Shoes are always pulled apart by internal springs. This helps range.”

An electric car Regenerative braking system, Whenever you release the throttle, it will reverse the rear motor (convert it into a generator to charge the vehicle’s battery), and it also functions as a drum brake. Volkswagen said that because the electric motor is mounted on the rear axle and automatically decelerates during regenerative braking, the rear brake is usually not used much. Then, if they are discs, you will be at risk of rusting or corrosion of the discs when you need them most. Drums are usually not affected by this problem because they are effectively isolated from the surrounding road environment.

A spokesperson for Volkswagen’s brake development department agreed, “Drum brakes seem to be outdated, but for electric vehicles like ID.4, it is the perfect solution.” They pointed out that the brake drum does not have The residual torque and resistance, wear and corrosion rates are low, which results in lower brake dust emissions than brake discs, which are the main advantages of the brake system.

Dr. Bernhard Klumpp, Head of Continental’s Hydraulic Brake System Business Unit, said: “The built-in drum brakes in ID.3 provide many benefits, especially in the field of electric vehicles. 2020 press statement, “For example, longer service intervals of up to 150,000 kilometers.” This is actually the service life of the vehicle.

In electric vehicles, The weight of the battery pack can be as heavy as the U-Haul trailerEvery gram is precious, and every ounce has a price. Although disc systems may be more effective than drums, they are also much more complicated mechanically-and those additional components, such as independent electronic brakes, will increase the overall quality and price of the vehicle.

Although drum brakes have existed since the 19th century, the technology itself is still evolving. For example, a variant of the Continental brake system used for ID.4 has been used in six other applications by various original equipment manufacturers.

“We initially started to develop [of this brake system], Including the electronic parking brake…” Alejandro Abreu Gonzalez, the engineering director of Continental’s hydraulic brake system department, told Engadget. “We have taken another step forward. Drum brakes will be completely With mechatronics, we will continue to invest in this technology. “


Continental previously committed to the development of an integrated disc brake system for the electric vehicle market in 2017, known as New wheel conceptThe company explained in a press release at the time: “The rim consists of two aluminum parts. The inner aluminum star wheel has aluminum brake discs, and the outer aluminum rim complements the tires.” Compared to the new wheel brakes, the New Wheel Concept brakes engage aluminum brake discs from the inside. This gives it a particularly large diameter, which is beneficial for braking performance.”

Gonzalez pointed out that although New Wheel was never actually put into production, this work “really gave us a lot of knowledge about new materials that reduce weight.” “That’s for sure, with heavy batteries, we will need to continue to develop.”

Gonzalez acknowledged that it is still a challenge to change the public perception that drum brake technology is outdated and inferior to disc brakes. But, although we may never see the return of the four-wheel drum system, especially in any high-performance and sporty vehicle, “For urban driving, I think this is the best technology that makes sense for electric vehicles.”

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