When it pertains to driving safety, nothing is more an essential than your tires and brakes. Here’s a overview to the two varieties of passenger-vehicle brakes, disc and drum. We define how lock work, exactly how they’re different and alike, why girlfriend may have actually both varieties on the exact same vehicle, what type of wear come expect and also what parts will need maintenance.


Braking mechanism Basics

Disc and drum brakes space both based upon a hydraulic pressure system. Braking starts with a mechanical force — her foot pressing the brake pedal.

You are watching: The function of a brake drum or rotor is to act as


A piston compresses brake liquid inside the grasp cylinder situated under your vehicle’s hood near your engine. This creates a many hydraulic pressure, generating a much bigger pressure than the of the little effort of pressing down on the pedal.The push is transferred via the brake fluid through the brake lines then through brake hoses (flexible tubes) that connect the lines with brake assemblies at each wheel.There, wheel cylinders transform that hydraulic pressure earlier to mechanical force. Brake friction product is pushed versus the brake bowl or drum, slowly or stopping your vehicle.Basics of disc Brakes

Disc brakes are uncovered on most vehicles today. They are mounted on the front axle and also often the rear as well. To protect against a wheel (and your car), a key brake uses a caliper fitted through brake pads to grab a rotate disc, or rotor.


The caliper is an assembly an installed to the auto with a bracket so that frames the rotor. That looks and functions prefer a c-clamp. That contains:

Brake pads: metal plates external inspection with product that provides stopping friction.One or 2 pistons to press the brake pads versus the rotor as soon as you brake.A bleeder screw to allow for servicing the brakes and replacing the fluid.A rubber piston seal that avoids brake liquid leakage and retracts the piston when the brakes release.A dust boot to save contaminants out of the cylinder.Anti-rattle clips that save the brake pads stable.


The rotor is do of actors iron or a steel/cast stole composite. That attached to the wheel hub and turns v the wheel. The the surface ar the brake pads contact. Once you step on the brakes, pressurized brake liquid pushes versus the pistons inside the caliper, forcing the brake pads versus the rotor. As the brake pads press versus both sides of the disc, the friction stops the wheel’s rotation.

Rotors have the right to either be solid or vented. Vented people have more surface area and also can an ext easily dissipate heat.


Two types of disc Brakes

There room two varieties of bowl brakes, called after the kind of brake caliper used: floating and also fixed.

A floating caliper (also dubbed sliding) is the most common type. It has actually one or two pistons. When the brakes space applied, the within brake pad is forced versus the bowl while, at the very same time, the caliper human body moves closer to the rotor. This activity forces the external brake pad versus the rotor.


The resolved caliper architecture has one or more pistons an installed on every side the the rotor. The caliper itself doesn’t budge: that rigidly fastened to a brake caliper bracket or the spindle. Once the brakes are applied, only the caliper pistons move, pressing the brake pads against the disc.


Basics of north Brakes

Drum brakes room an older layout of brake, not typical on today’s vehicles. As soon as they are provided it is only on the rear axle.

They don’t usage brake pads as the friction material. Instead of a caliper the clamps brake pads against a rotor, a north brake system has a wheel cylinder through pistons that press brake pair of shoes out against the within of a spinning drum. This contact slows and also stops the rotation that the brake drum and also the wheel.


Which Is Better?

Although they both run with the same an easy hydraulics, the two varieties of brakes do differently. Key brakes are more efficient, provide better stopping power, dissipate warmth easier and work much better in wet conditions, every while being less complex.

Most the today’s vehicles have disc brakes in ~ all 4 wheels. Some base models have actually disc on the former axle and drum on the rear, to keep costs down. In this models, why room disc put on the front and drum top top the rear? It’s as result of weight factors. A typical, unloaded vehicle is already around 10 percent heavier in front due to the engine. Then as soon as you fight the brakes, the weight of the automobile transfers to the front. An ext braking strength is necessary there, making it a project for key brakes.

Here’s more on exactly how disc and drum brakes compare.



Stopping power. Bowl brakes apply much more braking pressure faster, resulting in shorter stopping distances.

Heat management. Since they space exposed to air, bowl brakes cool better. Drum brake components aren’t as exposed to the air for this reason they take an ext time come cool down after braking. This can cause brake fade, a loss of avoiding power once friction product overheats.

Wet performance. Disc brakes perform better in wet conditions because they are open to the air and also can sling water turn off easily. Plus, the rotors get dried by the pads dragging throughout them. As soon as water gets within a drum brake it has tendency to get trapped within the drum, so that takes longer for the friction material to dried out.

Weight. Discs room lighter than drum brakes draft to apply the exact same force.

Emergency brake. A vehicle’s emergency brake is usually applied to the behind axle. This feature is much easier to download on a north brake than to a caliper or within the hub the a bowl brake rotor.


Cleaning. Key brakes are self-cleaning. The brake pads “wipe” the rotor off as soon as they’re engaged. North brakes room closed and are vulnerable to brake dust collecting indigenous the shoes, so they need periodic cleaning.

Repairs. North brakes have more hardware and also can it is in more complex to service. But drum brake shoes and wheel cylinders generally cost much less to change than bowl brake pads and calipers.


Since a lot of warm is created by the braking system, plenty have the right to go wrong. The plot of braking converts kinetic (moving) energy of the auto into thermal power (heat), subjecting countless parts to really high temperatures.

This way a lot of wear and tear also in common conditions. Part brake components will should be changed over the life the a vehicle. Yes no collection interval because that this since it depends on her driving style, climate and also road conditions.

The solution is just to get continual checks and replace pads, shoes and other components before braking is compromised or other parts acquire damaged.

Friction material

Disc brake pads slow-moving the rotor through friction and they wear with normal use. Eventually, they end up being too thin to function properly. Same thing for north brake shoes. The friction material on the shoe it s okay worn out and braking is compromised.

These contents should it is in inspected regularly. Girlfriend don’t desire to wait till pads/shoes wear down to the metal and also grind against the rotor or drum.

Other item in the braking system are simply as essential to store in good repair. Routine brake company should likewise include the following.

Brake fluid

The brake system should it is in checked frequently for leaks and also fluid have to be changed every few years (usually as soon as the brakes space serviced). Any kind of leak in the grasp cylinder, the brake fluid reservoir, the wheel cylinders, currently or hoses will minimize the hydraulic push that’s developed when brakes space activated. Basically, the device can’t generate adequate force necessary to produce braking power. You’ll an alert you have to push your brake pedal a lot more in order to slow-moving or stop.

Changing the end brake liquid occasionally is additionally essential. This liquid is particularly formulated to stop corrosion the the brake hydraulic components. However time and also moisture air pollution can damage its capacity to do this important job.

Moisture the infiltrates the fluid will mix v the brake fluid, lowering the cook point. Even though it resists evaporation, brake liquid will climate be much more likely to boil and turn right into vapor once it gets hot. There will certainly be less pressure in the hydraulic system, causing a short — possibly very low — brake pedal.

Along with moisture, the also really common because that impurities prefer rust, roadway grit or brake dust to acquire into the fluid, causing internal damages to parts and reducing braking performance.


These rubber rings save the hydraulic fluid from leaking and protect it from moisture and also contaminants. They also cause the piston to go back to its off place so the brake pads disengage properly when you release the brake pedal. If this doesn’t happen, you could experience brake drag and premature wear and also the automobile may traction to one side once you brake.

Brake Lines

Brake lines are steel tubes that connect the grasp cylinder to the brake hoses. A spongy brake pedal could mean wait has acquired into a line.


Brake hoses carry the hydraulic push from the brake lines to the wheel cylinders and also calipers. The rubber brake hoses flex, permitting the wheel cylinders and calipers to move up and also down v the wheels in relationship to the vehicle"s frame. If the rubber wears out, your automobile may pull to one side throughout braking or you may even get fluid loss and also brake failure. If yes wear inside the hose, small rubber particles deserve to restrict the circulation of fluid, leading to a brake traction or drag.


The rotor surface can thin unevenly indigenous the brake pad not releasing, leaving the pad in contact even as soon as the brake pedal isn’t activated. As soon as this happens, you’ll endure shaking or wobbling in the steering wheel when you brake.

Dust Boots

Brake components are continually exposed to roadway debris and brake dust. The dust boot prevents grime from entering the caliper piston. If it fails and can’t carry out its job, piston damages can occur, leading to brake drag, pulls and also premature wear.

Master Cylinder

Failing master cylinders deserve to leak internally. In this case, you may get a low or fading pedal without visible fluid loss. Consistent fluid maintain is important for prolonging cylinder life.

NOTE: over there are various approaches come brake service. Acquire informed around why it’s necessary to maintain more than just the brake pads or drum brake shoes.


Disc and drum brakes are built differently, with somewhat different advantages. Your automobile may have both or just disc brakes. Both work as part of the hydraulic brake system. This is a system that’s under high pressure, is subject to several heat and also can be endangered by road grime, air, brake dust and also moisture.

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It’s essential to get constant brake inspections come keep everything in suitable working condition. Describe your owner’s manual for a recommended schedule. Remember that funny brake sounds, smells or power are indicators you need to get your auto to the shop right away.