Brakes are an important component of every car and we rely on it not only to stop but also help us prevent a potential accident or collision. The car industry has progressed significantly from the early days of woodblock brakes to today’s sophisticated drum and disc brakes. Drum and disc brakes are the two most ubiquitous brake systems that you will find in today’s cars and in many cases, you will find both used on the same car. We explore the advantages and disadvantages of each system to tell you the differences.
Also Read – Anti Lock Braking System
Drum Brake vs Disc Brake
Drum brakes consist of a rotating drum with an enclosed brake shoe which is known for its durability and cost-effectiveness. The disc brakes use calipers to grip a spinning disc which offers a superior stopping power and heat dissipation which makes it perfect for high-performance vehicles.
| Feature | Drum Brakes | Disc Brakes |
| Stopping Power | Lower stopping power, especially at high speeds | Superior stopping power and responsiveness, especially at high speeds |
| Heat Dissipation | Poor heat dissipation, prone to overheating | Excellent heat dissipation, reducing brake fade |
| Cost | More affordable to manufacture and maintain | More expensive to manufacture and maintain |
| Maintenance | Simpler maintenance and inspection | More complex maintenance and inspection |
| Durability | Durable and long-lasting | Can be more prone to warping or needing replacement |
| Common Use | Rear wheels of economy vehicles and city cars | Front wheels and high-performance vehicles |
Drum Brakes
The first proper brakes on cars were the drum brakes, invented by French manufacturer Louis Renault in 1902. A drum brake consists of a drum, a housing connected to the wheel, brake shoes, which are fitted in the housing and a master cylinder that is connected to the brake pedal. When the brake pedal is pushed the master cylinder causes the brake shoes to rub against the inside of the rotating drum, creating friction and ultimately slowing down the wheel to a complete stop. Drum brakes are used on many mass produced cars and on the rear wheels on more premium car models.
Advantages of Drum Brakes
Durability: Since drum brakes have an increased friction contact area, they last longer.
Low Cost: Drum brakes are cheaper to manufacture, hence they are more widely used on almost all types of vehicles.
Low Input Force: Some drum brakes require low input force to get them activated, meaning less push on the brake pedal, this can be done through various means like hydraulic pressure.
Low maintenance: Due to better corrosion resistance, as they are inside of a housing, they are slightly easier to maintain.
Also Read – Types Of Cars
Disadvantages of Drum Brakes
Overheat: Drum brakes tend to overheat in high braking conditions like going down a hill or frequent high speed braking, as they don’t have an outlet to cool themselves down. This causes the brake shoes to glaze or smoothen out and produce no braking action.
Pushing The Brake Pedal Farther: When hard braking occurs, the drum expands slightly due to a phenomenon called thermal expansion. So, to induce braking the driver must press the brake pedal farther.
Grabbing: Grabbing in a drum brake occurs when the brake shoe becomes wet or is slightly rusty. This causes it to offer more braking force than required and stays that way for a brief moment of time. When a grab occurs, the tyres skid and keep on skidding even when the pedal is released. This results in a loss of control of the car and is dangerous for the driver, especially at high speeds.
Complex construction: A drum brake has many components, requiring an expert mechanic for repairs.
Also Read – Diamond Cut Alloy Wheels
Disc Brakes
Disc brakes were also introduced at the same time as drum brakes, but due to lack of proper technology and higher costs these didn’t take off. The first disc brakes were installed on a car called the Crosley Hot Shot, but then again due to insufficient research and reliability issues these were not popular. However, in 1953, Jaguar used disc brakes on its racing car at the Le Mans 24 hour racing event, and won the race, surprising everyone with its braking capabilities. The disc brakes fitted on the Jaguar racing car outlasted the other cars having drum brakes and thus made its winning debut. Since then disc brakes have been used in mass produced cars.
A disc brake contains a disc or a rotor, a caliper housing the brake pads and a piston. When the brake pedal is pushed, hydraulics force the piston in the caliper to push the brake pad on one side while backward force of the piston is used to pull the brake pad on the other side of the rotor. This produces a squeezing motion which pinches the disc at great force and hence slows or stops the vehicle.
Also Read – Engine Service
Advantages of Disc Brakes
Less Effort: Due to hydraulics as a standard on all disc brake systems, engaging a disc brake requires less effort and produces greater braking force.
Heat Dissipation: Due to the large surface area of discs any heat produced by friction of the brake pads on the disc dissipates into the atmosphere. This prevents overheating of the disc and improves braking even in frequent hard braking situations.
Standard Performance In Any Weather: Disc brakes perform well even in wet conditions and don’t slip or grab like their drum counterparts.
Easy Installation: A disc brake has a few components and hence very easy to install, even you can learn how to change the brake pads on your discs.
Disadvantages of Disc Brakes
Expensive: Disc brakes are downright expensive and that is the reason why car manufacturers opt for drum brakes on the rear wheels to bring down manufacturing costs.
Rotor Warping: In case of high speed braking there is a chance that the brake rotor might warp. This can happen due to very high temperatures on the discs followed by immediate cooling. Improper installation of the disc brake could also cause it to warp.
Brake Pad Wear Out: Brake pads on disc brakes tend to wear out faster than drum brakes, this happens due to the powerful squeezing motion of the brake piston on the brake pads. This provides better stopping power but reduced brake pad life.
Less Effective As Parking Brakes: The brake pads on discs tend to expand when heated and contract when cold. Since parking does not produce heat, the disc brakes are less likely to hold the wheels for a longer duration. This is the reason why high performance vehicles have an extra drum brake in addition to four wheel discs.
FAQs
Q. What is this disc brake?
Ans: A disc brake is a type of braking system that uses a metal disc (or rotor) attached to the wheel. Its calipers squeeze the brake pads against the disc which further creates a friction slowing down or stopping the vehicle.
Q. Why is disc brake better?
Ans: Disc brakes are better because they provide superior stopping power, better heat dissipation, and consistent performance while being more responsive and less prone to brake fade against drum brakes.
Q. What is the function of the disc brake?
Ans: The function of the disc brake is to slow down and eventually stop the vehicle by converting kinetic energy into heat through friction while ensuring quick and controlled braking with improved steering stability.
Q. Which is better, disc brake or ABS?
Ans: Disc brakes and ABS (Anti-lock Braking System) serve different purposes as the brakes are a mechanical braking component while the other is an electronic safety system preventing wheel lock-up during hard braking. These work together for optimal safety and control of the vehicle.
Q. Is it brake disk or disc?
Ans: When talking in automotive terms, the correct spelling is ‘disc brake’ while the ‘disk’ is used in the computing world.
Q. How much does it cost to replace disk brakes?
Ans: The approximate cost to replace disk brakes in India typically ranges between ₹3,000 to ₹8,000 per axle. The final price depends on the car model, parts brand and labour charges which make premium cars disk brake replacement more expensive.
Q. Why are disc brakes used?
Ans: Disc brakes are used because of their better performance, faster response, and improved safety compared to traditional drum brakes along with their effectiveness in both high-speed and emergency braking situations.
Q. What is the disadvantage of disc brakes?
Ans: The disadvantages of disc brakes are higher cost, more complex maintenance, and potential warping under extreme heat or prolonged use.
