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Address:No.168, getengping, Shifang village, Shifang Town, Wuping County, Longyan City, Fujian Province

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The difference between brake drum and brake disc in auto parts
Add Time:2019/10/25 14:05:46 From: Hits:2019
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Why do some cars use four-wheel brake discs, others use brake discs on the front wheels and brake drums on the rear wheels? Which system is better? What is a vented brake disc? Why do brake discs in the parts market have holes? I often ask a lot of questions about the brake discs. Let's find out.

For decades, four-wheel brake drums have been standard for cars. In the brake drum, hydraulic pressure is applied to the piston, which pushes the curved brake shoes out. The friction material glued or riveted to the brake shoes presses against the inside of the drum, slowing down the drum and axle rotation, and then these old cars stop - if all goes well!

In fact, sometimes brake drums work, but if you use only them to try to stop a high-speed car, you'll find their limitations: they decay. The brake drum is heated by friction, resulting in expansion. The brake shoes must move outward in order to reach the brake drum, which means that the brake pedal must be pressed deeply. The gas produced by the heating of friction material is also trapped in the brake shoe and brake drum, which weakens the braking ability. The first time you brake, the car may stop quickly from high speed, but when you brake the second time, your luck may not be so good.

Car manufacturers add heat sinks or aluminum materials to brake drums to cool them and metal brake linings, but this is not a solution for high-performance braking devices. The brake discs appear.

Brake discs have been used in aircraft and industrial applications. By applying hydraulic pressure to the caliper, the friction material (brake pad) holds the rotating brake pad. Brake discs do not seem to "catch" as easily as brake drums, so they provide better directional stability when parking. Different from closed brake drum, brake disc is open type, which has both advantages and disadvantages.

Since air can easily pass through the friction material, the brake disc can be cooled better. The ventilated disc has two friction surfaces separated by some heat sinks. This allows the air inside the disc between the friction surfaces to cool better. Most of the front brake discs are now vented because they do most of the braking work; most of the rear brake discs are non vented and have a "solid" disc, because the rear brake discs do not generate as much heat.

The brake disc also has the advantage that dirt and gas will be thrown out by the rotating brake disc, and the brake drum will collect dirt. The gas produced by water, oil and friction materials quickly disperses for better braking. Some brake discs have holes or grooves, partly for the sake of beauty, but also for practical use: the water and gas on the friction surface of the brake pads and discs can pass through the hole diameter, so that the brake device can play a role immediately without cleaning through the disc rotation. This is very important in the racing environment, but not very practical on ordinary roads. The holes reduce the area of the friction material and even block small stones, so they need more maintenance.

The biggest weakness of brake discs is that they are exposed to dust. The dust between the disc and the brake pad will wear the brake disc quickly. If the disc is too small, it will not emit heat, and it will burn in extreme environment; the electrode with too much wear must be replaced.

The front brake discs are located in relatively clean air, but the rear brake discs are exposed to dust and debris thrown out of the front tires. This is why the rear brake discs usually wear faster than the front brake discs, although they do only a small part of the braking work.

The ABS uses brake discs because they release quickly and smoothly. Although the brake shoe design and displacement changes now allow the brake drum to release more quickly, the effect of the brake disc is still better. For this reason, and in order to achieve maximum braking capacity, many cars are equipped with four-wheel brake discs.

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