How Does a Drum Brake Work

In this article, we’ll explore how drum brakes work, and look at how they differ from the more modern disc brakes.

What Are Drum Brakes?

They are called “drum” brakes because the main component resembles a drum. They function through a set of shoes or pads that press outward against a rotating drum-shaped part attached to the wheel. This friction slows the wheel, thereby reducing the vehicle’s speed. Despite the evolution of braking systems, drum brakes remain prevalent in many vehicles, particularly in the rear brake system, due to their efficiency and cost-effectiveness.

How Do Drum Brakes Work?

Drum brakes work by using brake shoes to create friction inside a drum. When you press the brake pedal, hydraulic pressure pushes the brake shoes outward against the spinning drum attached to the wheel, slowing down the car. Here’s how the different components work together:

The Drum: This is like the outer shell of a drum, attached to your car’s wheel. When the wheel turns, the drum turns too. It acts as the surface against which the brake shoes press to generate friction.

The Brake Shoes: Inside the drum, there are two curved pads called brake shoes. Think of these like the soles of your shoes, but instead of stopping you from slipping, they stop your car by creating friction.

The Wheel Cylinder: Activated by hydraulic pressure from the master cylinder when the brake pedal is pressed, it pushes the brake shoes outward against the drum.

Springs: Just like a spring pulls a door closed after you open it, springs in the brake system pull the brake shoes back away from the drum when you release the brake pedal. This way, the shoes don’t keep rubbing against the drum and wearing out when you’re not braking.

What is the Difference between Drum Brakes and Disc Brakes?

While drum brakes are efficient, the car industry has seen a shift towards disc brakes, especially for the front wheels of modern vehicles. Here’s how they differ:

Design: Disc brakes use a disc-shaped part that spins with the wheel, with brake pads clamping onto this rotor to slow the vehicle, as opposed to the drum and shoe method.

Cooling: Disc brakes dissipate heat more effectively due to their open design, making them more suitable for high-performance applications and reducing the risk of brake fade under heavy use.

Maintenance: Drum brakes can be more complex and time-consuming to service due to their many components and the need for regular adjustment.

Performance: Disc brakes generally provide more consistent performance, especially in wet conditions, due to their ability to shed water and debris more efficiently than drum brakes.

Do modern cars still use drum brakes?

Several cars still use drum brakes, particularly for the rear wheels such as the Skoda Enyaq. Notably, some EVs like the Volkswagen ID.4 and Audi Q4 e-tron feature rear drum brakes. Despite the general trend in the automotive industry towards disc brakes, this choice is primarily due to the advantages in reducing rolling resistance, which helps improve efficiency and range for EVs.

EVs heavily rely on regenerative braking systems, where the electric motor reverses to slow the vehicle and simultaneously recharge the battery. Since regenerative braking handles a large portion of the braking load, the demand on the traditional friction braking system is reduced. Thus, the high performance of disc brakes might not be necessary, and drum brakes can be sufficient.

In summary, while drum brakes continue to be a reliable and cost-effective choice for many vehicles, especially in rear brake systems, the shift towards disc brakes in modern automotive design highlights brake discs’s superior performance, especially in wet conditions.

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Louanne is a marketing and communications professional in the automotive tech industry currently at ClickMechanic, boasting over 5 years of experience.

Louanne’s work at ClickMechanic might revolve around branding and customer engagement, but her passions extend far beyond the marketing sphere. A true foodie at heart, she loves exploring diverse cuisines and talking about her culinary adventures across the world. Her writing prowess shines through in her car-related blog content, where she offers invaluable driving tips and practical car repair advice.

In her Suzuki Jimny 4-wheel drive, Louanne combines her sense of adventure with her automotive know-how, transforming every drive into a lesson and a pleasure.