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Brake Drums: How They Work and What You Should Know

A brake drum is a cylinder that is attached to a car’s wheel. When the brake pedal is pressed, the brake shoes inside the brake drum are pushed outwards to slow the car down.

A few decades ago, the disc brakes began to replace drum brakes. Disc brakes provide higher braking force and are considered safer. However, drum brakes are still used on many new automobiles, mostly on budget models and nearly solely on the rear wheels.

Drum brakes have been around since 1900, when they were first employed on a Maybach automobile, though Louis Renault didn't patent the technology until 1902.

How Brake Drums Work

Hydraulic wheel cylinders, brake shoes, and a brake drum make up a drum brake system. When the brake pedal is depressed, hydraulic wheel cylinders force two curved brake shoes with a friction material lining against the inner surface of a revolving brake drum. As a result of this contact, friction is created, allowing the vehicle to slow or stop.

Pneumatic brake fluid is forced through the brake lines and into the brake cylinder when you press the brake pedal. A pair of springs in the cylinder is forced against a piston at each end of the cylinder.

Each piston is forced against one of the two long, curved brake shoes attached to the wheel via the lug nuts. The shoe comprises a metal base and a friction-material pad that contact the drum, slowing and stopping the wheel.

Importance of Brake Drums

The brake drums are important for the following reasons:

  • One of the most important safety-related car elements is the brake drum. It has a long service life and is relatively low-wear. However, if the wear limit is surpassed (the inner diameter exceeds the legal limit) or other damage (such as the wheel bearing) happens, reliable braking is no longer possible.
  • One brake drum provides a friction pair that slows the wheel's rotation with the brake shoe. The brake drum is also responsible for collecting and releasing heat generated while braking. This is especially significant as the friction between the braking drum and the brake shoe lining decreases as the temperature rises.

Benefits of Brake Drums

Drum brakes have the following advantages:

  • Drum brakes can provide more braking force than disc brakes of comparable diameter
  • Drum brakes have a large friction contact surface; therefore, they last longer
  • Drum brakes production costs are comparatively lower
  • Drum brakes generate less heat
  • Drum brakes have built-in self-energizing action; less input force is required (such as hydraulic pressure)
  • Drums brakes are easier to recondition when compared to brake calipers
  • Drums brakes have superior corrosion resistance than discs and maintenance is required less frequently

Issues with Brake Drums

Brake drums can occasionally develop problems because of their hollow, enclosed construction.

  1. When a large amount of heat cannot be released, "Long Pedal" occurs. This is more likely to happen if you brake too hard when driving down a hill. The heat generated by the friction will cause the drum to expand, as almost all materials that have been heated do.

The driver will have to push the pedal substantially further to achieve the same amount of contact to slow the car as the drum walls expand away from the brake shoes. This will reverse when the brake drum slows down, although it's best to avoid extended braking when traveling downhill. Avoiding extending braking is a recommendation that applies to both drum and disc brakes. The brake drum's design isn't particularly problematic, but it may take longer to service or replace than a normal disc brake.

  1. Asbestos was previously used in the brake shoes of antique cars as part of the friction material. This is no longer an issue with current cars but may resurface if work is done on an older vehicle.
  1. Water can become trapped inside the drum and get stuck in between the brake shoes and drum walls which reduces friction and braking ability.

5 Tips To Maintain Brake Drums

Here are some helpful hints for keeping your vehicle's drum brakes in good working order:

  • Make sure the brake drum isn't rusted.

Keep your brake drum clean to avoid rusting as the friction side of the drum must be free of scratches and cracks for the vehicle to brake. If the brake drum needs to be replaced, it must be replaced on both sides of the axle to prevent the braking system from malfunctioning.

  • Choose an all-in-one brake drum rear kit.

When replacing drum brakes, make sure to choose a high-quality kit that includes all of the necessary components.

  • Maintain a reasonable speed.

The faster you drive, the quicker your brakes wear out. If you feel vibrations, shaking, or noises when braking, you should visit a brake system repair workshop or reach out to NuBrakes to get an inspection.

  • Examine the brake fluid

Monitor your vehicle's brake fluid and make sure you replace it every 30,000 miles or two years using the manufacturer's recommended fluid.

  • Visit a reputable workshop

Braking systems are important to your safety on the road. Having your brake drums regularly inspected by reputable mechanics, such as those at NuBrakes will help give you peace of mind.

Conclusion

If you have drum brakes on your car, they are essential for keeping you and your vehicle safe. Make sure to inspect the drum brake for wear and effectiveness as part of routine repair and maintenance.

Only high-quality manufactured components should be used if the brake drums or other sections of the drum brake need to be replaced. If you are worried about your brake drums and looking for the most convenient automobile service experience, NuBrakes makes brake repair convenient and affordable for everyone by combining our mobile model with the personal, friendly touch of our certified brake repair technicians.

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