Why old-fashioned drum brakes may be the future path for EVs

Drum brakes are an OG technology that has been used for almost as long as automobiles. First developed in 1899, this style of brake is found in some of the first car prototypes manufactured by Wilhelm and others. Maybach And Louis Renault.. Drum brakes have long been the standard means of slowing down vehicles, given their decent performance and low manufacturing costs, which are slightly younger than their disc-style alternatives. But in the mid-1960s, when there were shorter stop discs, it began to lose the support of automakers. Brake system It became popular. Today, the most common drum brakes on medium to heavy trucks and buses are Electric car..

Drums and discs behave very differently, and each system has its advantages. Disc brakes have a pair of pads attached to the caliper that push down to create friction and slow down the wheel. The disk system is more powerful and faster than the drum. Front brakes are very necessary as they carry 60-80% of the vehicle’s momentum that slows down compared to the rear. so that, New car Already with a front drum. The disc also has an auto-adjustment feature that makes it less likely to grab or pull, and the auto-cleaning feature makes it quieter. In addition, there is little warpage due to long-term exposure to heat, and it does not fade even in severe braking conditions.

Conversely, the drum places the brake shoes in a cylindrical can that rotates with the rest of the wheel, and uses a piston to push the two shoes outward and against the inner wall of the drum, the vehicle. Creates friction that slows down. Due to the large surface area inside the cylinder, the drum shoes can be much larger than the disc pads, last longer than the same size disc caliper pads, and provide greater stopping power. In addition, the drum is further back in the wheel assembly, making it easy to use as a parking brake or emergency brake, but vehicles with four-wheel discs require the addition of a standalone e-brake.

In the latest generation of electric vehicles, drum brakes really make a lot of sense.take VWof And EV, For example.Both models use rear drum brakes designed by Continental “Drum brakes have no residual brake resistance by design,” said a spokesman for VW’s North American EV test team. Engadget.. “The shoe is always pulled open by an internal spring. It helps the range.”

EV Reverses the rear motor in reverse each time you release the accelerator (converts it to a generator to replenish the vehicle’s battery) and functionally matches the drum brakes. According to VW, the rear wheel brakes are rarely used because the electric motor is mounted on the rear wheel axle and automatically decelerates during the regenerative braking process. Therefore, using discs at the rear risks rusting and corroding the discs when most needed. Drums are generally unaffected by this issue as they are effectively shielded from the surrounding road environment.

Spokesperson from Volkswagen AG’s Brake Development Department agreed: “Drum brakes seem obsolete, ID.4, It’s the perfect solution. They pointed out that the main advantages of the braking system are the lack of residual torque and drag on the drum, and the lower wear and corrosion rates, which emit less brake dust than the disc.

“The drum brakes built into ID.3 offer many advantages, especially in the field of electronic vehicles,” said Dr. Bernhard Crump, Head of Business Unit for Continental’s Hydraulic Brake Systems. Stated. , “For example, longer service intervals of up to 150,000 kilometers.” That is effectively the life of the vehicle.

In EV , Every gram is valuable and every ounce costs money. Disk systems may be more effective than drums, but they are also much more complex mechanically. All additional components, such as stand-alone e-brake, increase the overall curb weight of the vehicle and the price of the sticker.

Drum brakes have been around since the 19th century, but the technology itself is evolving. For example, the Continental braking system variation used in ID.4 is already in use in six other applications for various OEMs.

“We first started development [of this brake system], To include electronic parking brakes … ”Alejandro Abreu Gonzalez, Engineering Director of Continental’s Hydraulic Brake Systems Division, said: Engadget.. “We have another step forward that will be completely electromechanical for drum brakes, we continue to invest in this technology.”

Continental has previously worked on the development of an all-in-one disc brake system for the EV market in 2017. .. “The wheel rim is made up of two aluminum parts. The inner aluminum carrier star has aluminum brake discs and the outer aluminum rim has tires,” the company explained in a press release at the time. Did. “In contrast to traditional wheel brakes, the new wheel concept brake engages the aluminum disc from the inside, which allows for particularly large diameters and improves braking performance.”

The New Wheel was never actually produced, but this work “provided a lot of insight into new materials to reduce weight,” Gonzales said. “This is definitely a heavy battery and we need to continue developing.”

Gonzales acknowledges that changing the general perception that drum braking technology is outdated and inferior to discs remains a challenge. However, especially in high-performance cars and sports cars, the four-wheel drum system will not be revived, but “I think that it is the best technology suitable for EV here in urban driving.”

Why old-fashioned drum brakes may be the future path for EVs

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