What are Drum Brakes and How Do They Work?

Drum brakes use a fairly simple hydraulic design. A cylinder sits sideways in the wheel and when pressure is applied to the brake pedal the hydraulic mechanism extrudes bores that put pressure on the friction surface of the wheel, slowing the vehicle.

What are Disc Brakes and How Do They Work?

Disc brakes use some of the same friction principals as drum brakes, however, they are applied in a much different way. With disc brakes, a hydraulic vice sits around the rotor, when the brake pedal is applied several pistons apply pressure to both sides of the rotor, slowing the vehicle.

Why Are Disc Brakes More Popular?

Disc brakes allow the braking system to employ more points of contact, allowing for greater stopping power. Another reason they are more popular is that they are easier to disassemble and maintain.

Combinations

When a vehicle stops, the front brakes provide the majority of the stopping power. Due to this fact, many car companies are able to lower the cost of their vehicles by installing the more powerful disc brake design on their front wheels, while utilizing the older drum brake design in the rear.

Safety Concerns

While a car with disc brakes on all its wheels will provide superior stopping capabilities to its operator than a car with mixed braking technologies or an all drum configuration, there is no reason to be alarmed if an operator is driving a car using drum brakes. They provide adequate stopping power and safety.

Source:

Happy Living: Drum Brakes

Edmunds.com: Brakes