Vacuum braking system: Definition, Components, working, Pros, Cons, Applications

Vacuum braking system: Definition, Components, working, Pros, Cons, Applications

What is vacuum braking system?

Vacuum braking system is a type of braking system that uses a vacuum to assist in applying the brakes. It utilizes a vacuum pump or connection to the engine’s intake manifold to create the necessary force.

When the driver presses the brake pedal, the vacuum is used to amplify the force and engage the brakes.

Components of the vacuum braking system  

Components of a vacuum braking system typically include:

Vacuum Braking system components
Vacuum Braking system components

Vacuum Booster:

This component uses the vacuum pressure to amplify the force applied by the driver on the brake pedal, providing power assistance to brake application.

Master Cylinder:

The master cylinder is responsible for converting the force applied by the driver into hydraulic pressure. It distributes the hydraulic pressure to the individual brakes.

Brake Pedal:

The brake pedal is the interface between the driver and the braking system. When the driver presses the brake pedal, it initiates the braking process.

Vacuum Lines: 

These are the pipes or hoses that carry the vacuum from the vacuum source (vacuum pump or engine intake manifold) to the vacuum booster.

Check Valves: 

Check valves are one-way valves placed in the vacuum lines. They ensure that the vacuum is maintained within the system and prevent the loss of vacuum pressure.

Brake Calipers/Cylinders: 

These components are responsible for applying the pressure to the brake pads or shoes, creating friction against the rotors or drums, which slows down the vehicle.

Brake Pads/Shoes: 

These are the friction materials that make contact with the rotors or drums when the brakes are applied. They generate the necessary friction to stop the vehicle.

Brake Rotors/Drums: 

These are the rotating components on which the brake pads or shoes make contact. The friction between the pads or shoes and the rotors or drums generates the stopping force.

Note: The specific components may vary depending on the design and type of vacuum braking system used in different vehicles.

Working of vacuum braking system?

The working of a vacuum braking system can be summarized in the following steps:

1. Creation of Vacuum: 

The vacuum for the braking system is created either by a dedicated vacuum pump or by tapping into the engine’s intake manifold. The vacuum source generates a partial vacuum, typically around 18-22 inches of mercury (inHg).

2. Vacuum Booster Activation:

 When the driver presses the brake pedal, it initiates the braking process. The pedal movement activates the vacuum booster, which is connected to the brake pedal mechanism. The vacuum booster contains a diaphragm and a valve mechanism.

3. Vacuum Assistance: 

As the driver applies force to the brake pedal, the vacuum booster utilizes the vacuum pressure to amplify the force. The diaphragm within the vacuum booster is pushed by the differential pressure created between atmospheric pressure and the vacuum. This amplifies the force exerted by the driver, making it easier to apply the brakes.

4. Hydraulic Pressure Generation: 

The amplified force is then transmitted to the master cylinder. The master cylinder converts this force into hydraulic pressure. Inside the master cylinder, there are pistons and seals that generate the hydraulic pressure as the driver continues to apply force to the brake pedal.

Vacuum brake booster
Vacuum brake booster

5. Brake Application: 

The hydraulic pressure generated by the master cylinder is distributed to the individual brakes through brake lines. The pressure reaches the brake calipers (in disc brake systems) or brake cylinders (in drum brake systems). The hydraulic pressure forces the brake pads or shoes against the rotors or drums, creating friction that slows down the vehicle.

6. Brake Release: 

When the driver releases the brake pedal, the vacuum booster disengages, and the hydraulic pressure in the system is relieved. This allows the brake pads or shoes to retract, releasing the braking force and allowing the vehicle to move freely.

Vacuum braking system working youtube video

Features of Vaccum braking system 

Vacuum Braking system Features
Vacuum braking system features

Power Assistance: 

The vacuum in the system amplifies the force applied by the driver on the brake pedal, making it easier to apply the brakes. This power assistance reduces the physical effort required by the driver, especially in situations that demand sudden or hard braking.

Reliable Operation: 

Vacuum braking systems are known for their reliability. They have fewer moving parts compared to some other braking systems, reducing the likelihood of mechanical failure or malfunction. Additionally, the vacuum source is generally independent of the vehicle’s electrical system, providing a reliable backup in case of electrical failures.


Vacuum braking systems are relatively simple and cost-effective compared to more advanced braking systems. The absence of complex electronic components and sensors makes them easier and less expensive to manufacture, install, and maintain.

Compatibility with Older Vehicles: 

Vacuum braking systems were commonly used in older vehicles, and many vintage or classic cars still utilize this system. Therefore, the key feature of a vacuum braking system is its compatibility with older vehicle models, making it a suitable choice for preserving the originality and authenticity of vintage automobiles.

However, it’s worth noting that vacuum braking systems have limitations compared to modern braking systems, such as hydraulic braking systems and electronic braking systems (ABS). These advanced systems offer improved control, responsiveness, and safety features, making them the preferred choice in most contemporary vehicles.

Pros of vacuum braking system?


Vacuum braking systems are relatively simple in design and have fewer components compared to more advanced braking systems. This simplicity can lead to easier maintenance, troubleshooting, and repairs, as there are fewer parts to inspect or replace.


Vacuum braking systems are generally less expensive to manufacture and maintain compared to more complex braking systems. The absence of electronic components and sensors reduces the overall cost, making vacuum braking systems a cost-effective option, particularly in budget-conscious scenarios.

Backup System:

Vacuum braking systems often serve as a backup or secondary braking system in modern vehicles equipped with more advanced braking systems. In case of a failure or malfunction in the primary braking system, the vacuum braking system can still provide some braking force, allowing the driver to stop the vehicle safely.

Compatibility with Vintage Vehicles: 

Vacuum braking systems were commonly used in older vehicles and are still found in many vintage or classic cars. They offer compatibility with older vehicle models, preserving the authenticity and originality of these vehicles. Retrofitting modern braking systems into vintage vehicles can be challenging and expensive, making vacuum braking systems a practical choice for maintaining the historical integrity of these automobiles.

Reliability in Certain Conditions: 

Vacuum braking systems can offer reliable performance in certain conditions where other braking systems may encounter challenges. For example, in off-road or low-traction situations, where excessive moisture or dirt can affect the operation of electronic or hydraulic systems, a vacuum braking system may provide a more dependable braking solution.

Cons of Vaccum braking system?

Limited Braking Power: 

Vacuum braking systems have limited braking power compared to hydraulic or electronic braking systems. The force generated by the vacuum booster is dependent on the vacuum level, and it may not provide sufficient braking force in certain situations, such as high-speed emergency stops or when towing heavy loads.

Reduced Responsiveness: 

Vacuum braking systems generally have slower response times compared to hydraulic or electronic braking systems. The delay in transmitting the force from the brake pedal to the brakes can result in longer braking distances, particularly in critical situations where quick and precise braking is essential.

Vacuum Dependency: 

Vacuum braking systems rely on a consistent vacuum supply to function properly. If there is a leak in the vacuum lines, a malfunction in the vacuum pump, or a loss of engine vacuum, the braking performance can be significantly affected or completely lost. This dependency on vacuum makes the system more susceptible to failures or malfunctions.

Limited Control and Features: 

Vacuum braking systems lack the advanced control and safety features found in modern braking systems, such as anti-lock braking systems (ABS), traction control, or stability control. These features provide enhanced stability, control, and maneuverability in various driving conditions, contributing to overall safer braking performance.

Compatibility Limitations: 

While vacuum braking systems are suitable for older vehicles, they may not be compatible with newer vehicle models that require more advanced braking systems to meet safety and regulatory standards. Retrofitting a vacuum braking system into a modern vehicle might not be feasible or may require extensive modifications, making it impractical.

Overall, while vacuum braking systems have served as effective braking solutions in the past, their limitations in terms of braking power, responsiveness, control features, and compatibility with modern vehicles have led to their replacement by more advanced braking systems.

Applications of Vaccum braking system? 

Vacuum braking systems have been used in various applications in the past, particularly in older vehicles and specific industries. Some notable applications of vacuum braking systems include:

Vacuum braking system in cars: 

Vacuum braking systems were commonly used in older cars, trucks, and motorcycles. They were prevalent in vehicles manufactured before the widespread adoption of hydraulic braking systems and electronic braking systems. Many vintage or classic vehicles still utilize vacuum braking systems for authenticity and preservation purposes.

Vacuum braking system in trains: 

Vacuum braking systems were historically used in some railway systems, particularly in older steam-powered locomotives. These systems relied on vacuum pressure to apply the brakes on train cars, ensuring safe deceleration and stopping. However, modern railway systems have transitioned to more advanced braking technologies, such as air braking systems.

Vacuum braking in  Agricultural Machinery: 

Vacuum braking systems have been utilized in some agricultural machinery, such as tractors and heavy-duty equipment. These systems assist in applying the brakes on agricultural vehicles, providing controlled stopping power during operations in fields and on uneven terrain.

Vacuum breaking in Industrial Machinery: 

Vacuum braking systems have found applications in various industrial machinery, such as material handling equipment and heavy machinery. They have been used to provide braking capabilities, ensuring safe operation and controlled stopping in industrial settings.

Manufacturers of Vaccum braking system?

Some well-known manufacturers of braking systems include:


Bosch is a global technology company that offers a wide range of automotive components and systems. They have expertise in various braking technologies, including regenerative braking systems, which may involve vacuum-based or vacuum-independent designs 

TRW Automotive: 

TRW Automotive, now a part of ZF Friedrichshafen AG, is a leading supplier of automotive safety systems, including braking systems. They provide innovative braking solutions for both conventional and advanced braking technologies.

Akebono Brake Industry:

Akebono Brake Industry is a Japanese manufacturer specializing in braking systems for various applications, including automotive and industrial sectors. They produce a wide range of braking components and systems, including vacuum-related technologies.

Continental AG: 

Continental is a major automotive technology supplier that develops and manufactures various components, including braking systems. They offer advanced braking solutions for different vehicle types, including electric and hybrid vehicles.


Knorr-Bremse is a prominent manufacturer of braking systems primarily focused on the commercial vehicle sector, including trucks, buses, and trains. They produce a range of braking systems, which may include vacuum-based technologies for specific applications.

Please note that this list is not exhaustive, and there may be other manufacturers in the market producing vacuum braking systems or related components. It is recommended to conduct further research or contact specific manufacturers for more detailed and up-to-date information regarding their product offerings.


Difference between Vacuum braking system and Air braking system?


Vacuum Braking System

Air Braking System

Operating Principle

Relies on vacuum pressure to assist in braking

Relies on compressed air to assist in braking

Source of Power

Engine intake manifold or dedicated vacuum pump

Compressed air from an air compressor

Braking Force

Limited braking force compared to air brakes

Higher braking force than vacuum brakes

Response Time

Slower response time

Faster response time


Relatively simple and fewer components

More complex system with additional components

Brake Pedal Feel

Lighter pedal feel due to vacuum assistance

Firmer pedal feel due to higher air pressure


Used in older vehicles, vintage cars, and some industrial machinery

Commonly used in commercial vehicles, heavy-duty trucks, and railway applications

Safety Features

Limited or no advanced safety features

Advanced safety features like ABS and EBS


Generally less expensive compared to air brakes

More expensive due to additional components and features


Becoming less common in modern vehicles

Widely used in commercial vehicles and railway industry

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