Disc brakes are the most common type of braking system found in consumer vehicles today. Like a lot of car components, disc brakes are often taken for granted. Most people know very little about the brakes on their car except that they cause the vehicle to slowdown and stop once they step on the pedal. Yet disc brakes are arguably the most important part of any automobile in terms of safety. Without well-functioning disc brakes, most cars would be dangerous to operate. Here is a primer on what they are and how they work.
What Are Disc Brakes?
Disc brakes are located beside the tires of a vehicle. They use a caliper to squeeze pairs of brake pads against a disc (or rotor) to create friction. This friction slows the rotation of the vehicle axle that turns the tires. As a result, a vehicle slows and eventually stops completely. As you might imagine, the friction from disc brakes causes a lot of heat, which is why disc brakes are vented to allow excess heat to escape. Disc brakes can be found on both the front and rear tires of most modern vehicles.
How Do Disc Brakes Work?
In many ways, disc brakes are like the brakes found on bicycles. The same braking principal applies between disc brakes on cars and hand brakes found on bicycles. Bike brakes also have a caliper that squeezes brake pads against the wheel. The difference is that disc brakes squeeze a rotor rather than the wheel itself, and the force applied is transmitted hydraulically instead of through a cable as on a bicycle. Both disc brakes and bicycle brakes use friction between pads and a disc to slow a moving vehicle. Vented disc brakes have a set of vanes on either side of the disc that pump air through the disc to cool them.
Vehicles that don’t operate with disc brakes typically use drum brakes instead. Drum brakes consist of a brake drum attached to the inside of the wheel. When the brake pedal is engaged, hydraulics press two brake shoes against the brake drum. This creates the friction needed to slow and stop a vehicle. Drum brakes used to be the main type of braking system in vehicles worldwide but have been largely replaced by more reliable disc brakes. Today, drum brakes are used most often on heavy duty trucks. Almost all vehicles manufactured these days now use disc brakes.
Who Invented Disc Brakes?
The very first automobile disc brake was used on Lanchester cars manufactured in Birmingham, England in 1902. However, the limited choice of metals at the time meant that disc brakes had to be made of copper, a softer metal that wears out quickly. As such, disc brakes were dismissed as impractical. Forty years later, during World War II, the Daimler Company company developed disc brakes for use on their four-wheel drive armored cars. The German army also used disc brakes on some of their tanks during the war.
After the Second World War, the Chrysler Corporation began experimenting with disc brakes on its more expensive luxury cars such as the Chrysler Crown and the Town and Country Newport – selling disc brakes as a $400 upgrade at the time. The first company to mass produce disc brakes and put them on vehicles as a standard option was Citroën, which placed them on all its family-friendly Citroën DS cars beginning in 1955. Disc brakes eventually caught on in America in the 1960s, as brands such as Studebaker and Chevrolet began to mass produce them.