What is the difference between drum brakes and disc brakes?
2 Answers
1. Structural comparison: The principle of drum brakes is to add pistons inside the brake drum, which are pushed by hydraulic pressure to press against the brake drum, generating friction to achieve the braking effect. On the other hand, disc brakes apply hydraulic pressure to the caliper, causing the friction material to clamp the brake disc, thereby achieving the braking effect. 2. Principle comparison: The principle of drum brakes involves hydraulic pressure pushing the pistons, causing the brake shoes on both sides to press against the inner wall of the wheel, thus achieving the braking effect. Due to the forward motion of the wheel, the rolling force generated will react on the brake drum, amplifying the braking force, which affects ride comfort. In contrast, disc brakes use a hydraulic pump to push the brake caliper, thereby applying force to the brake pads to achieve the braking effect. Therefore, the braking force directly depends on the pressure of the brake caliper and is not amplified like drum brakes, resulting in inherently smaller braking force. 3. Advantage comparison: Drum brakes provide greater braking force, allowing for timely stopping in emergencies and effectively avoiding accidents. Due to the large inertia of heavy trucks, which require higher braking strength, drum brakes have an irreplaceable position in heavy trucks. Disc brakes, being an external braking system, offer good heat dissipation and easy control, allowing for high-frequency intermittent braking and integration with ABS intermittent braking.
I've driven quite a few cars, from old classics to modern new ones, and experienced the differences between drum brakes and disc brakes. Drum brakes are hidden inside the wheel, shaped like a drum, and rely on internal shoes pressing against the drum surface to brake. They have a simple structure and low cost, which is why many budget cars still use them on the rear wheels. The downside is poor heat dissipation—after a few brakes on a steep slope or under heavy load, they overheat, and the braking force drops noticeably, making driving feel less secure. Disc brakes, on the other hand, are outside the wheel, shaped like a plate, and the caliper clamps directly onto it. They dissipate heat very well, making them especially safe at high speeds or during emergency braking, which is why modern cars prefer using them on the front wheels or all four wheels. Disc brakes respond quickly and perform reliably even in rainy conditions, though they are a bit more expensive. Having used both types, I find disc brakes more worry-free for daily driving—safety comes first, and the extra cost is worth it.
