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How Your Parking Brake or Emergency Brake Works and When to Use It

October 26, 2017

As a driver or passenger in any modern car, you may have noticed the large lever in between the front seats or a smaller pedal positioned way away from the other pedals. It's not there just for looks. This is the parking brake, also known as the hand brake, emergency brake, or e-brake.

What is a parking brake?

The parking brake or emergency brake is a latching mechanism typically connected to the rear wheels which is used to keep your car in a stable position. The emergency brake acts as a backup to the primary service brake, which is the brake that activates when you step on the pedal while driving. If the service brake fails, the emergency brake can keep your car from moving while it should remain parked.

The emergency brake is a completely mechanical ratcheting system that will operate even if the vehicle loses electrical power or the hydraulic system fails in the service brake. The name "brake" is a bit misleading because the emergency brake is primarily used to prevent the car from rolling while it is already parked, but in rare cases, when done properly it can be used to make the car come to a stop in the event that the primary brakes fail.

hand brake

Hand brake / Image source

Types of parking brakes

There are four types of parking brakes:

  1. Center lever - A large lever located in between the driver and passenger seats. This is the most common type of parking or emergency brake found in modern vehicles. To engage a brake of this type you simultaneously push a button on the handle and pull up on the lever. To disengage the brake, you simply push the button and press down on the lever until it's back in the initial position.
  2. Pedal - Located far to the left of the primary brake and gas pedals, usually adjacent to the driver’s side door. This is the second-most common type of emergency brake. Push down on the pedal to engage the brake. There is usually a secondary lever or handle located nearby that releases the emergency brake.
  3. Stick lever - A lever that you push or pull to engage, located underneath the steering wheel or instrument panel. This type is usually only found in older-model vehicles.
  4. Electric - A button located amongst the other controls found on the console of most newer-model vehicles, especially hybrids and electric vehicles. The driver presses the button to both engage and release the emergency brake. There is typically a dashboard indicator light that shows when the emergency brake is in use.

How does the parking brake work?

The parking or emergency brake is operated with a purely mechanical system of cables whereas in most cars, especially modern vehicles, the primary brake system operates on hydraulics. A hydraulic system can fail for a number of reasons, and in the event that that happens, the emergency brake will still be operable.

The system connects the parking brake pedal or lever directly to both rear brakes using emergency brake cables in a "Y" shape. How the emergency brake actually works to hold the car in place depends on what type of brakes the vehicle has, either drum or disc brakes.

Drum Brakes

Cars with drum brakes have the brake components housed inside of a drum located against the rear wheels. Inside the drum are brake shoes that press against the drum when the brake pedal is pressed to apply friction against the drum and slow the wheels down.

The cable for the emergency brake is directly connected to the brake shoes and physically pulls the shoes against the drum when the emergency brake is engaged. Drum brakes are primarily found in older model vehicles.

parking brake shoe

Parking brake shoe

Disc Brakes

In cars with disc brakes, instead of all the brake components being housed inside of a drum, there is a spinning brake rotor located beside the wheels with two brake pads on either side that press against the rotors to stop the wheels when the brake is applied.

There are two configuration styles for the emergency brake cable system in cars with this type of brakes. In some cars, the emergency brake is comprised of a mini drum within the rear rotors. When the emergency brake is engaged, the lever manually pulls the brake shoes into the drum within the rotor and stops the wheels from moving.

The other configuration, mainly found in cars with four-wheel drive, manually attaches the cables to a caliper piston located on the rear wheels. When the emergency brake is applied, the cables press the caliper piston against the brake pads which apply pressure to the rotor and prevents the wheels from moving.

When to use the emergency brake

The primary purpose for the emergency brake is to act as a secondary method of stopping the car's wheels from moving in the event that the primary brake / park system fails. In everyday driving, the emergency brake is most commonly used to secure the car once parked, especially when parking on an incline.

In vehicles with automatic transmission, when you shift the car into park, it engages the "parking pawl", which is a pin that notches in between the output shaft in the transmission and prevents engine power from transferring to the wheels.

In most vehicles, especially modern ones, the parking pawl and automatic transmission system is highly reliable. But like anything else, the parking pawl can wear out over time or break completely. Parking on an incline and utilizing the parking pawl as the primary method to keep the vehicle secure is a major cause of it wearing down faster than usual and it can be very expensive to replace.

Manual transmission vehicles do not have this mechanism. Unless you apply the emergency brake, there is no mechanical system in place to prevent the car's wheels from rolling, especially if you are on an incline.

A far less common use for the emergency brake is to actually stop the vehicle when in motion. While the hydraulic brake systems installed in most cars, especially modern ones, are very reliable, there may be some instances where the brakes fail. In these cases you'll need to react quickly to avoid an accident. As a last resort, your emergency brake can be applied gradually to make the car come to a halt. If necessary to use your emergency brake to stop a moving vehicle, it is very important to not slam on the parking brake pedal or yank on the hand lever because it can cause the rear wheels to lock and make you lose control of the car, especially if you are moving at a high speed.

Other things to know about your parking brake

  • Use the emergency brake often to keep it working properly. Since the emergency brake operates on a purely mechanical system, the cables are subject to corrosion. Frequent normal use (when parking) can prevent the cables from being corroded or stuck in place.
  • Disengage the emergency brake before moving the vehicle. Trying to move the vehicle with the emergency brakes on can cause damage to the brake itself, to the rotors, and the car's transmission.

About the Author

RepairPal is the leading online source of auto repair resources and estimates. With many ASE Master certified mechanics on staff who have decades of experience, RepairPal knows all the fine points of car repair.

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