What does the parking brake hold?

The parking brake holds the vehicle in place by locking the rear brakes to prevent wheel rotation and unwanted movement, especially on hills. It acts as a dedicated, supplementary safeguard to the main braking system when a car is parked.

What the parking brake holds

The parking brake works by applying the rear brakes so that the wheels cannot rotate. This holds the entire car in place, serving as a safeguard on hills and in preventing wind or inadvertent movement when parked.

• It clamps the rear brakes (drums or discs) to stop wheel rotation and prevent rolling on slopes or level ground.


• It can function independently of the engine, so you can set it with the engine off or running, depending on the vehicle.


• In most vehicles, the parking brake also acts as a backup to the transmission’s parking mechanism, providing redundancy if the main system fails.


• On modern cars with electronic parking brakes, an electric motor actuates the rear calipers or drums via a control unit for reliable engagement.


• Some systems include features like auto-hold or hill-hold that maintain brake force temporarily when going from brake to throttle.

In practice, the parking brake’s job is to prevent movement while parked, not to stop a car in motion. It is a dedicated brake function that complements the service brakes rather than replacing them.

How it works across different systems

Parking brakes come in a few configurations, with the core goal of preventing movement. Here is how the major types operate and what drivers should know about each.

• Cable-operated (manual) parking brake: A hand lever or foot pedal pulls a cable that clamps the rear brake shoes or calipers. The result is a mechanical hold on the rear wheels.


• Electronic parking brake (EPB): An electronic switch sends a signal to a control module, which powers an electric motor to apply the rear brake calipers or drums. It often includes auto-release and hill-hold features.


• Hybrid/Brake-by-wire implementations: In some vehicles the parking brake control is integrated with the main braking system, using sensors and actuators to engage the rear brakes as needed.


• Auto-hold and hill-hold capabilities: Some EPB systems automatically engage or maintain braking on a slope when the driver’s foot leaves the brake pedal, improving start-off safety.

Regardless of the mechanism, the function remains the same: to keep the vehicle stationary by applying friction to the rear wheel brakes and resisting movement, particularly on inclines.

Safety and best practices

Understanding how and when to use the parking brake improves safety and longevity of the braking system. Here are guidelines for responsible use.

• Engage the parking brake every time you park, especially on hills or windy conditions, to reduce the chance of rolling away.


• Never rely on the parking brake to serve as the primary means of stopping a moving vehicle. Always use the service brakes to stop and then apply the parking brake after coming to a complete stop if needed.


• Be mindful of icy or wet conditions; a portion of the parking brake might not grip as well on slick surfaces. Use wheel chocks on steep or slippery grades if available.


• Regularly test the parking brake after parking to ensure it holds the vehicle, and have the system inspected if you notice slipping, unusual noises, or a soft lever feel.


• For manual transmissions, place the car in gear (or in first/reverse on a slope) in addition to engaging the parking brake to reduce strain on the parking pawl and brakes.

Following these practices helps maintain effectiveness and extends the life of the brake components while ensuring the vehicle remains secure when parked.

Maintenance and common issues

Like any brake component, the parking brake requires periodic inspection and maintenance to stay reliable. Common issues include cable wear, stretched cables, seized calipers or drums, and worn rear brake linings. Regular checks by a qualified technician can prevent unexpected failure.

• Inspect the parking brake cable for fraying, corrosion, or kinks and adjust as needed to ensure full engagement and release.


• Check rear brake pads or shoes for wear; worn components reduce holding power and can compromise safety.


• Test the system: after applying the brake, try slightly moving the car with light throttle to confirm it holds.


• Ensure the release function works smoothly; a sticking brake can leave the rear brakes engaged, leading to overheating or binding.


• In vehicles with EPB, keep the battery and control module in good condition, as a fault in the electronics can prevent the brake from applying or releasing correctly.

Routine maintenance helps prevent rollaways and extends brake life, making the parking brake a dependable safeguard.

Summary

The parking brake holds the vehicle in place by applying friction to the rear brakes, preventing wheel rotation and unwanted movement when parked. It can be cable-operated or electronically controlled, with modern systems offering auto-hold and hill-start features. Use it regularly on inclines, don’t rely on it to stop a moving car, and maintain the system to keep it reliable.

What holds the parking brake in place?

Parking brakes are completely mechanical and use only cables and levers to operate. When a parking brake lever is pulled (or when a parking brake pedal is pushed), these cables transmit the necessary force to keep your vehicle in place or to stop the vehicle.

What is parking brake hold?

When activated, Automatic Brake Hold retains brake pressure when the vehicle comes to a stop such as at a traffic light or in heavy traffic. This frees the driver from continually pressing the brake pedal to maintain the vehicle in a stopped position until the driver presses the throttle pedal.

What does the parking brake lock?

The emergency brake bypasses your vehicle's hydraulic brake system to lock the wheels in place. This mechanical system uses cables that are attached to the emergency brake lever. When engaged on cars with drum brakes, the cables pull another lever that puts pressure on the brake shoes to hold the vehicle.

Does the parking brake lock all wheels?

No, a standard parking brake does not lock all wheels; it typically locks only the rear wheels of the vehicle. The system is designed to hold a parked vehicle still, but it operates separately from the main hydraulic brakes. In some specialized vehicles, like certain trucks or those in 4WD mode, the parking brake may engage more wheels.
 
You can watch this video to learn how parking brakes work: 55sspeedkar99YouTube · Nov 4, 2019

• Rear wheels only: In most cars and light trucks, the parking brake uses cables to actuate the brakes on the rear wheels. This is the standard system because it's less expensive and simpler to install, as the front wheel hubs are connected to the steering system. 
• Less efficient: Using the parking brake to stop a moving vehicle is less efficient than using the main brakes because it primarily acts on the rear wheels, which are lighter under braking due to weight transfer. 
• Special cases: Some heavy-duty trucks may have a parking brake that acts on multiple rear wheels. Additionally, some 4-wheel drive vehicles will have a parking brake that engages all four wheels when in 4WD mode, because the front and rear axles are linked together. 
• Electronic parking brakes: While electronic parking brakes are becoming more common, they also typically apply only to the rear wheels. 

This video explains how 4WD affects the parking brake system: 1mTeam O'NeilYouTube · Dec 12, 2019