Many drivers who understand the difference between these two types of brakes often believe that drum brakes are outdated and not suitable for modern cars. However, plenty of drivers use them without any complaints. So, which type of brake is better – disc or drum brakes?
Despite advances in electronic safety systems that assist with deceleration and braking, the final stopping power still comes from one of two mechanical brake types: disc or drum brakes.
Braking mechanisms that stop each wheel come in two types: drum and disc brakes. The difference lies in the shape of the rotating component that moves with the wheel and is slowed down by the braking system. In both cases, brake pads apply pressure to a circular surface, creating friction to slow the vehicle.
Drum Brakes
In a drum brake system, a cylindrical drum is attached to the wheel hub and rotates along with it. Inside the drum, hydraulic pressure forces two brake shoes outward, pressing them against the inner surface of the drum.
Since the brake shoes push outward, the drum must be strong and is typically made of heavy-duty metal, making it quite bulky and expensive. While the drum itself lasts a long time, its weight increases the unsprung mass, slightly affecting ride smoothness. Although engineers can compensate for this added weight by adjusting the suspension springs and shock absorbers, excessive weight is still undesirable.
Additionally, drum brake systems include several extra components, such as springs to return the brake shoes to their original position and mechanisms for engaging the brake shoes. In modern cars, drum brakes are only used on the rear wheels, where they also incorporate the parking brake system, which operates separately but uses the same drum and shoes.
Advantages of drum brakes:
- Longer lifespan – drum brake components wear out much slower than disc brakes.
- Cost-effective – simpler manufacturing makes them more affordable and easier to repair.
For the last 50 years, drum brakes have been used exclusively on rear wheels in passenger cars. The reason? Rear wheels contribute much less to braking force, making drum brakes sufficient for the job.
Disc Brakes
The key difference in disc brakes is that they use a flat metal disc instead of a drum. This disc is squeezed from both sides by a pair of brake pads, generating friction to slow the vehicle.
Advantages of disc brakes:
- Better heat dissipation – less risk of overheating and brake fluid boiling.
- Lighter and more efficient – no excess metal mass like in drum brakes.
- Simpler mechanism – no springs or extra components to return pads to their original position. Instead, the pads retract slightly due to the elasticity of a rubber seal.
At first glance, disc brakes seem simpler, but they require more advanced manufacturing due to the high precision needed for parts. Additionally, disc brakes on rear wheels require a separate parking brake system, which can complicate the design. In some cases, manufacturers add a small drum brake inside the disc just for the handbrake function.
Conclusion
Yes, disc brakes are generally more effective than drum brakes under the same conditions. However, real-world conditions vary depending on the vehicle type and axle placement. Modern design methods allow engineers to perfectly optimize drum brakes for the necessary braking performance.
If you’re driving a family car rather than a sports car, rest assured that factory-installed drum brakes on the rear wheels will be more than sufficient for your needs.