Auto Anatomy: Brake Actuator

All About Brake Actuator: Components, Working & More

  • What is a Brake Actuator?
  • Location of Actuator
  • Brake Actuator Parts
  • How It Works
  • Potential Problems
  • FAQs

When compared to light vehicles, heavy vehicles function a bit differently. They are designed to safely carry and transport heavy loads from point A to point B. Heavy vehicles have much larger moving components and more powerful speed-controlling mechanisms. Instead of hydraulic brakes, air brakes are used in heavy vehicles. These types of brakes are applied using the principle of friction with the help of a brake actuator. Let’s learn more about this crucial mechanical device of the braking system in heavy vehicles.

More About Brake Actuator Importance and Role

More about brane actuator function
Understanding more about brake actuator working

The actuator is a small but integral part of the air braking system in heavy vehicles. The device plays a crucial role in balancing heavy-duty braking forces. As a pneumatic device, the help applies air pressure to the brakes when the brake is applied. 

Brake Actuator Operation

When it comes to functioning, brake actuators act like relays. They release bursts of air to the truck’s braking system whenever the driver presses the brake pedal. Whether there are disc or drum brakes in heavy vehicles, the actuator works similarly for both.

Brake Actuator Location

Brake actuators are located on the rear axle of the vehicle. For trucks with trailers, it is located near electrical and airline connections for towing trailers. The positioning of actuators plays a crucial role in eliminating delays in the braking process. 

Optimal performance of actuators in the braking system is essential to ensure road safety in heavy vehicles. The inspection of trailers and semi-trailers by RTA Dubai is a crucial precautionary measure in this regard.

Brake Actuator Components

Simple in appearance and small in size, actuators undertake important tasks in the braking system. It functions with the help of the following components:

brake actuator importance greatly depends on its components and working
Here are some key brake actuator components


The diaphragm is made of rubber. It is designed to flex back and forth to regulate airflow.

Upper chamber

The purpose of this chamber is to hold compressed air. The compressed air passes from the truck’s airlines to the lower chamber.

Lower chamber

The lower chamber holds the build-up air pressure, which then goes to the trailer brakes.

Exhaust valve

The exhaust valve is designed to vent build-up air pressure from the lower chamber after the braking process.

Failure of any of these components may partially or completely impact the actuator’s performance. Add all such crucial components to the ultimate truck inspection checklist to ensure optimal vehicle performance.

Brake Actuators Working

Brake actuator maintenance play crucial role in ensuring road safety
The actuators start responding as soon as the driver hits the pedal

Air in the system flows freely from the upper chamber to the lower chamber when the brake pedal is free. The air channels through the open ports and equalises pressures between the upper and lower chamber.

As soon as the driver presses the brake pedal, the actuator starts responding. It drops the air pressure in the upper chamber to apply brakes. As a result of the pressure imbalance, the flexible diaphragm bends downward into the lower chamber.

The bent diaphragm blocks the ports, which traps pressurised air in the brake’s chamber lines. This sudden burst of air pressure applied to the brakes brings the vehicle safely to a stop.

The moment brakes are released, the bent diaphragm goes back to its original position. This restores the flow of air between chambers through the ports. This is just one aspect of how the air brake system operates. The working of disc brakes is another intricate mechanism to learn about.  

Potential Problems for Brake Actuator Maintenance

Brake actuators ensure responsive brakes, which is crucial to safely drive a heavy vehicle. These mechanical components contribute to heavy-duty braking mechanisms and are subject to wear and tear. Check out some common symptoms of a malfunctioning actuator in the braking system:

Less Responsive Brakes

A noticeable delay in brake response could mean that brake actuators are not activating to their full potential.

Reduced Braking Power for Trailers

Trucks with trailers can face this problem. A malfunctioning actuator fails to supply enough air pressure resulting in a weaker brake application. This may also be one of the causes of the vehicle pulling to one side.

Problematic Pressure Gauge Reading

Actuators have a gauge that gives readings about air pressure. However, if the pressure gauge shows a low reading, this indicates the air is leaking out of the system.

Damaged Hoses

This is a common cause of a failing brake actuator. Check the condition of the rubber hoses for possible cracks or bulges that can be problematic. Such kind of hose damage can create blockages in the airflow to the actuator, preventing it from creating the required air pressure.

An expert diagnosis for any of the aforementioned brake actuator issues. For an optimal solution, visiting a well-reviewed bus repair centre in Dubai or other emirates would be feasible.


What happens when a brake actuator fails?

Failing brake actuators may lead to uneven braking. It can be an alarming situation for a heavy vehicle on the road. Besides optimally functioning brake actuators, here are some other ways to control heavy-duty vehicles.

Can you drive without a brake actuator?

It’s not recommended to drive a heavy vehicle with a failing brake actuator. It may increase the risk of different types of vehicle accidents. 

This was everything to know about the importance and functioning of brake actuators. The efficient functioning of such components is crucial for road safety. Moreover, abiding by the RTA laws for heavy-duty vehicles is also essential to drive safely and responsibly.

Aspiring truck owners can also search the pre-owned market to pick a vehicle according to their requirements. There are plenty of used trucks for sale in the UAE to choose from.

For more updates on brake actuator types and problems, stay connected with the dubizzle Cars blog.


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