How does the braking system in a vehicle work?
The brakes in a car are one of the most important safety-related systems in a vehicle. They enable the driver to reduce speed, bring the vehicle to a controlled stop, and reliably master dangerous situations. Despite their central importance, many drivers are not exactly sure how a modern braking system actually works, which components are involved, and how different types of brakes differ from one another.
The braking system in a car is based on a sophisticated interplay of mechanical and technical elements. The design, mode of operation, and differences between disc brakes and drum brakes illustrate how this system ensures controlled stopping.
The function of the braking system
The fundamental task of brakes in a car is to reduce kinetic energy in a controlled manner and convert it into heat. This reduces the speed of the vehicle or brings it to a safe stop. As a central safety-related system, the braking system is an indispensable prerequisite for the safe operation of a vehicle. In addition, the braking system plays a central role in the safety and stability of the vehicle. It ensures that forces act evenly during deceleration and that the vehicle remains controllable even in unexpected situations or difficult driving conditions.
Key components of the braking system
A modern braking system in a car consists of several coordinated components that together form the braking system. Each of these elements fulfills its own function and is indispensable for safe braking. The precise interaction of all components ensures that the braking system works reliably and that the brakes in the car respond in a controlled and safe manner in every driving situation.
Brake pedal
The brake pedal is the direct interface between the driver and the braking system. Pressing the pedal triggers the braking process and transfers the force applied by the driver to the car's braking system. The position of the pedal determines how hard the brakes are applied, allowing the driver to finely control the braking power. The brake pedal is therefore the starting point for the entire braking function in the car.
Brake booster
The brake booster supports the pedal force applied by the driver and ensures that even slight pedal pressure enables effective braking. It significantly reduces the amount of force required, thereby increasing driving comfort and safety. Within the car's braking system, the brake booster ensures that the braking system responds quickly and reliably, even in stressful situations.
Master brake cylinder
The master brake cylinder plays a central role in the braking system. It converts the mechanical force applied via the brake pedal and brake booster into hydraulic pressure. This brake pressure forms the basis for the function of all other components in the car's braking system and enables the individual wheel brakes to be supplied evenly.
Brake lines
The brake lines transmit the pressure generated in the master brake cylinder to the individual wheels. They are an essential component of the hydraulic brake system, as they enable uniform and instantaneous power transmission. Damage or leaks in the brake lines can significantly impair the function of the brakes in the car and must therefore be checked regularly.
Brake fluid
Brake fluid is the transmission medium within the brake system in a car. It ensures that hydraulic pressure is transmitted quickly and evenly to all wheel brakes. In order for the brakes in a car to work reliably, the brake fluid must be of consistent quality, as it can absorb moisture over time and lose its effectiveness. For this reason, regular replacement is an important part of maintenance.
Wheel brakes
The wheel brakes on the wheels themselves are responsible for actually slowing down the vehicle. Depending on the design of the brake system in the car, either disc brakes or drum brakes are used. These components convert the kinetic energy of the vehicle into heat through friction, thereby slowing it down. As the final link in the braking system, the wheel brakes are crucial for the actual braking effect of the brakes in the car.
The drum brake
Structure of a drum brake
The drum brake is a classic component of a car's braking system and is mainly found in combination with other brakes in the car within the overall braking system. It consists of a closed brake drum that is firmly connected to the wheel. Inside the drum brake are brake shoes with friction material applied to them. These are mounted in such a way that they can press outwards against the inner surface of the drum during braking. As part of the car's braking system, the drum brake contributes significantly to the deceleration of the vehicle.
Braking process with drum brakes
When the brakes are applied in a car, hydraulic pressure builds up in the brake system, which acts on the wheel brake cylinder of the drum brake. This pushes the brake shoes apart so that they press against the inner wall of the brake drum. The resulting friction converts kinetic energy into heat and slows down the wheel.
Thanks to its closed design, the drum brake is well protected from dirt, water, and other environmental influences within the car's braking system, which increases its reliability in everyday use.
Typical areas of application for drum brakes
In modern vehicles, drum brakes are often used on the rear axle, where they supplement other brakes in the car's braking system. They are considered robust, durable, and low-maintenance, and are therefore a proven component of many braking systems. However, due to their limited heat dissipation, drum brakes react more slowly to high loads than disc brakes, which is why they are not usually used on the front axle.
The disc brake
Structure of a disc brake
Today, disc brakes are the most commonly used type of brake in cars and a central element of modern car braking systems. They consist of an open-design brake disc that rotates with the wheel and a brake caliper that houses the brake pads. Depending on the design, the brake caliper can be fixed or floating. The disc brake is specially designed to absorb high braking forces and to work reliably within the entire braking system, even under heavy and frequent use.
Braking process with disc brakes
When the brakes are applied in a car, the brake system generates hydraulic pressure, which presses the brake pads in the brake caliper against the rotating brake disc. The resulting friction slows down the wheel and reduces the speed of the vehicle. The open design of the disc brake allows for effective heat dissipation, which keeps the braking performance stable even with frequent braking in the car. This allows the braking system in the car to respond directly and evenly to different braking requirements.
Typical areas of application for disc brakes
Disc brakes are now used in almost every car's front axle braking system and are increasingly being installed on the rear axle as well. Within the braking system, they impress with their high braking performance, precise controllability, and reliable function under high loads. They also offer better heat dissipation than other designs. These characteristics make disc brakes indispensable, especially for modern vehicles, higher speeds, and demanding driving situations.
Safety systems for braking systems
The most important assistance systems in a car's braking system include the anti-lock braking system (ABS), the electronic stability program (ESP), and the brake assist system. These systems are permanently integrated into the braking system and work continuously in the background to provide optimum support for the car's brakes in critical situations.
The anti-lock braking system (ABS) prevents the wheels from locking up during heavy braking and the vehicle from skidding. It continuously monitors the wheel speed and regulates the brake pressure on each disc brake or drum brake individually. This maintains the grip between the tires and the road, so that the vehicle remains steerable even during emergency braking. The driver can avoid obstacles and maintain control of the vehicle even on slippery roads.
The Electronic Stability Program (ESP) supplements the function of the braking system in the car by detecting unstable driving conditions. As soon as the vehicle threatens to skid in curves or during sudden evasive maneuvers, ESP intervenes in a targeted manner by braking individual wheels and adjusting the drive power. In this way, the braking system actively contributes to driving stability and reduces the risk of skidding or rollover accidents.
Brake assist supports the driver, particularly in dangerous situations. It detects emergency braking based on the speed and intensity of pedal operation and automatically provides maximum braking force. This allows both disc brakes and drum brakes within the car's braking system to reach their full performance potential, even if the driver does not brake hard enough due to stress or uncertainty.
Maintenance as the key to safety
The operational safety of a vehicle depends largely on the condition of the braking system. Even a technically efficient system can only function reliably if all safety-related components are working properly. Car brakes are subject to continuous wear and tear and must therefore be checked and serviced regularly.
Brake components subject to friction are particularly susceptible to wear, especially brake pads, brake discs, brake shoes, and other mechanically moving parts. As wear increases, the effective friction surface area decreases, resulting in longer braking distances and reduced deceleration performance. In addition, increased thermal stress on worn components can impair the stability of the braking effect and cause uneven braking behavior.
Another safety-related component of the brake system is the brake fluid. It is responsible for hydraulic power transmission and is hygroscopic, which means that it absorbs moisture over time. This lowers the boiling point of the brake fluid and can lead to the formation of vapor bubbles under high loads. As a result, pressure transmission in the hydraulic brake system is impaired, which can manifest itself in delayed or reduced brake response.
Conclusion
A functioning braking system is a fundamental prerequisite for road safety. The braking system in a car consists of a multitude of mechanical, hydraulic, and electronic components that must work together precisely to ensure reliable deceleration. From the brake pedal to the hydraulic power transmission to the wheel brakes, each component performs a clearly defined task within the overall system. The differences between drum brakes and disc brakes show that different designs are used specifically to meet requirements for braking performance, load capacity, and economy. The braking system is supplemented by modern assistance systems that intervene to stabilize the vehicle in critical situations and support control over the vehicle.
However, the condition of the entire brake system remains crucial for long-term functionality and safety. Wear, thermal stress, and aging of the brake fluid have a direct impact on braking performance. Regular maintenance ensures that the brakes in the car function reliably and that the required level of safety is maintained at all times.