Reliable brakes are integral to the safe operation of any car, of course. They slow and stop your car by converting the kinetic energy of the rotating wheel into heat energy via friction. When your braking pedal is depressed, pads press against the drum or rotor, triggering the energy conversion. The main considerations with a vehicle's braking system are the brake type and actuator mechanism.

Today, we'll briefly discuss the operation of drum and disc brakes. I'll describe how each system works to slow your vehicle and the individual components involved in the process.

Drum Brakes

Most vehicles that roll off the automaker's factory floor are equipped with one of two types of braking assemblies: drum or disc. Each type offers inherent advantages over the other, but your car's make and model will ultimately determine which type is used.

With drum assemblies, a drum that is attached to the wheel houses two semicircular shoes. When activated, the shoes press against the drum, slowing your car. Actuators sit between the two shoes at a specific edge; when triggered, they twist. This twisting motion forces the shoe against the drum. When the pedal is released, the shoes retract via a set of springs.

Depending on the configuration of the actuator, the drum structure may be labeled "single leading edge" or "double leading edge." The term "leading edge" refers to the location in which the actuators are installed and therefore the point of drum contact. Single leading edges have one actuator while double leading edges have two for maximum contact.

Disc Brakes

Disc-based assemblies perform much better than their drum counterparts. As a result, they're more likely to be found in sports cars and other high-performance automobiles. A disc brake system uses a caliper assembly that overlaps the rotor, a metal plate attached to the wheel. A caliper mechanism contains hydraulic cylinders. When it is activated, it presses pads against the rotor, thereby slowing your vehicle.

A rotor is not simply a solid plate that directly bolts to the wheel. In reality, floating rotors are used because the tolerance in a regular, one-piece assembly is very small. If the unit is off by as little as 0.07 mm, damage and large amounts of vibration can result.

Floating rotors rely upon float buttons to connect the carrier and main rotor; the carrier bolts directly to the wheel. These buttons allow a small amount of lateral movement, reducing warping and vibration.

Along with floating designs, rotors are also cross-drilled to improve performance. When pressure is applied, a gas layer can form between the pad and rotor surface, reducing performance. Cross-drilling removes this problem by providing an area for the trapped gas to escape.

Keeping Your Car's Brakes In Good Condition

Most drivers will never need to know what I've just described. However, the more you understand about your car's parts, the better prepared you'll be when you visit your mechanic. The important thing is that you keep your vehicle's brakes in good condition. If you notice squealing or a lack of pressure, have an auto technician take a look. Replacements may be a small investment, but your safety on the road may depend upon it.