Understanding Disc Brakes and Drum Brakes


Your tyres and brakes are essential for safe driving. In this article, we are looking at disk brakes and drum brakes to see how they operate and how they differ from each other. These two parts are based on the hydraulic pressure system that carries out the operation of brakes. When your foot presses the brake pedal, it creates a mechanical force that signals to the operation of the braking system.

There is a piston that creates a compression force on the brake fluid which results in an increase of hydraulic pressure. The pressure generated has a force greater than what you used to just press the brake pedal. The generated pressure will then be transferred through the brake lines and hoses via brake fluid. The hydraulic pressure is again converted to a mechanical force by wheel cylinders and brake friction material is then pressed against the brake drum or brake disc. This will result in the vehicle slowing down or coming to a complete stop. You can find disc brakes in many vehicles and they will be mounted at the front and rear axles. The disc brake has a caliper with brake pads. This caliper is mounted to the vehicle framing the brake rotors. The calliper has brake pads, one or more pistons, a rubber piston seal, anti-rattle clips, a breeder screw and a dust boot that keeps dust and other contaminants away from the cylinder. When you brake, the brake pads are pressed onto the rotor by the pistons. The piston seal will prevent brake fluid from leaking and when you take your foot off the brake pedal, the seal will retract the piston.

There are floating and fixed disc brakes. The floating disc brake is more common and when brakes are applied, there is an inner brake pad that presses against the disk. Simultaneously, the caliper will move closer to the rotor forcing the outer brake pad against the rotor.  There are more pistons in a fixed caliper design. When brakes are applied, the caliper will not move but the caliper pistons will start to move forcing the brake pads against the brake disc. Drum brakes are not that common in modern vehicles and they were only used on the rear axle as opposed to disc brakes that are used in front and rear both. The friction materials in drum brakes are not brake pads as used in disc brakes. The drum brakes use a wheel cylinder that has pistons. These pistons will push the brake shoe against the inner side of a rotating drum which will result in the vehicle slowing down.

The same rule of hydraulics applies to both disc brakes and drum brakes. But when you look at efficiency, disc brakes are more efficient and have higher stopping power. Disc brakes have a shorter stopping distance than drum brakes making them a lot safer. They can also deal with heat that comes with friction better and they perform better than drum brakes in wet conditions. Drum brakes are more complicated than the disc brakes and therefore need more repairs and servicing.

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