Difference Between Drum Brake And Disc Brake

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Drum brakes

Drum brakes are a type of mechanical braking system used in cars, trucks, and motorcycles. They have been part of automotive braking systems for many years, although disc brakes have gained more popularity in recent times due to their superior performance.

Drum brakes consist of several essential components. The primary element is the brake drum, a round, cylindrical component that rotates with the vehicle’s wheel. Inside the drum are a set of brake shoes, which are typically made of friction material like asbestos or other composites. When the brake pedal is pressed, hydraulic pressure is used to push these brake shoes outward against the inner surface of the drum, creating friction and slowing down the vehicle.

Components

The basic components of a drum brake system include a brake drum, brake shoes, wheel cylinder, brake backing plate, and various springs and levers. When you press the brake pedal, hydraulic pressure is applied to the wheel cylinder, which pushes the brake shoes outward against the inner surface of the brake drum. This frictional force between the brake shoes and the drum creates the necessary stopping power to slow down or stop the vehicle.

Working Principles

When the driver applies the brake pedal, hydraulic fluid is directed to wheel cylinders located within the brake drum. This hydraulic pressure causes the brake shoes to move outward, pressing against the inner surface of the drum. The friction generated between the stationary drum and the moving brake shoes converts the kinetic energy of the vehicle into thermal energy, ultimately slowing it down. When the pressure on the brake pedal is released, return springs retract the brake shoes, allowing the wheel to spin freely again.

Advantages

Drum brakes are simple and durable. The design is straightforward, and the components are less exposed to external elements compared to disc brakes, making them less susceptible to corrosion and wear. This durability is especially beneficial in heavy-duty applications like trucks and buses, where reliability is needed.

Also drum brakes is their self-adjusting mechanism. Over time, as the brake shoes wear down, the self-adjusters automatically compensate for this wear, ensuring consistent braking performance. This feature minimizes the need for frequent manual adjustments, making drum brakes more user-friendly and reducing maintenance requirements.

Drum brakes also have good heat dissipation characteristics. The brake drum’s large surface area allows for effective heat dissipation, preventing overheating during prolonged or heavy braking. This feature is particularly important in applications like commercial vehicles and trailers, where braking loads can be substantial.

When it comes to disadvantages, Drum brakes have a tendency to fade under heavy and repeated braking. As the heat generated by braking builds up, the frictional performance of drum brakes can degrade, leading to reduced braking efficiency. This fade can result in longer stopping distances and decreased overall braking performance.

Furthermore, drum brakes are generally less responsive than disc brakes. Due to their design, it takes more time for the brake shoes to make contact with the drum and generate sufficient friction to slow down the vehicle. This slower response time can be a concern in situations requiring rapid and precise braking, such as emergency stops or high-performance driving.

Disk Brakes

Disc brakes offers superior stopping power and control compared to traditional drum brakes. These braking systems operate on the principle of friction, where two components – a rotor (also known as a brake disc) and brake pads – work together to slow down or stop the vehicle.

Components

The central part is the brake rotor, a flat, circular metal disc that rotates with the wheel. Brake calipers are mounted on the vehicle’s suspension and house the brake pads. These brake pads are made of friction material, often a composite of various materials like metal, ceramic, or organic compounds. When you press the brake pedal, hydraulic pressure is applied to the brake calipers, causing the brake pads to squeeze against the rotor, generating friction and ultimately slowing down the vehicle.

Operation Principle

When the driver presses the brake pedal, hydraulic fluid is forced through the brake lines to the calipers. This hydraulic pressure pushes the caliper pistons, which, in turn, press the brake pads against the rotating rotor. The friction generated between the rotor and the brake pads converts the vehicle’s kinetic energy into thermal energy, effectively slowing it down. When the brake pedal is released, the hydraulic pressure subsides, allowing the brake pads to retract, allowing the rotor to spin freely once again.

Advantages

They provide rapid and consistent deceleration, making them highly effective in emergency situations. Disc brakes are also less prone to fading, which is a reduction in braking efficiency due to overheating. Their open design allows for efficient heat dissipation, ensuring that they maintain their performance even during heavy or prolonged braking.

Moreover, disc brakes are self-cleaning to a certain extent. As the rotor rotates, it helps to shed water, debris, and dirt from the brake pads, ensuring consistent braking performance in various conditions. Disc brakes also offer better modulation and control, allowing drivers to apply precise amounts of braking force, enhancing safety and stability.

Drum Brake And Disc Brake: Key Differences

Points of ComparisonDrum BrakeDisc Brake
NatureThe drum brake uses a cylindrical drum.A disc brake uses disc-shaped rotors.
AvailabilityA drum brake is available at a cheaper price as compared to Disc brake.But it is available at a costlier price.
UseIt is used for trucks, buses, scooters.It is used for modern bikes or cars.
BrakingIt is slow braking.It is fast and instant braking.
DissipationSlower heat dissipation.Faster heat dissipation.
High TemperatureAt high temperatures, the performance is reduced.Here at a high temperature, the performance is not reduced. Good braking even at high temperatures.
Main ComponentThe drum brake uses an expanding hydraulic cylinder to press the frictional material against the inside of a rotating drum.A disc brake uses a clamp called calipers to hold the friction pads against the rotor disc.
DesignDrum brake has a complex design.The design of the disc brake is easy.
Ventilation PropertyLow ventilation property.Better ventilation property as compared to drum brake.
WeightA drum brake is almost 20 to 30 percent more than disc brake weight.The disc brake has a low weight.
Anti-fade CharacteristicsDrum brake having poor anti-fade characteristics.Disc brake having better anti-fade characteristics.
Replacement of PadsHere changing or replacing frictional pads is difficult.But Here changing or replacing frictional pads is not difficult. It is easy to change.
WearIn drum brake Non-uniform wear of frictional force.Disc brae has Uniform wear of frictional forces between pad and disc.
Self-locking AbilityA drum brake is self-locking.A disc brake is never self-locking.
Maintenance CostThe drum brake maintenance cost is less.The maintenance cost is more.
OperationDrum brake operated mechanically.But Dis brake operated mechanically and ABS technology and others too.
EfficiencyThis is less efficient and when we stop the engine it takes more time butHere the disc brake is more efficient and when we stop it stops fast as compared to the drum brake.
InspectionDrum brake inspection is difficult.Disc Brake inspection is easy.
Brake-fluidHere no fluid is used in the brake system so there is no maintenance.In Disc brake, fluid is used so maintenance is there. When vehicle use after a long time we must check the fluid of disc brake.
TorqueThe torque transmitting time is less in drum brake but incase ofDisc brake the torque transmitting time is high.