What Are Brake Retarders?

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Brake retarders, also known as engine brakes or exhaust brakes, are devices used in vehicles to assist with braking and control the speed of a vehicle. They are commonly found in heavy-duty trucks and buses, but can also be used in other types of vehicles such as RVs and motorhomes. Brake retarders work by using the vehicle’s engine to create resistance and slow down the vehicle, reducing the wear and tear on the brakes and improving overall safety.

How Do Brake Retarders Work?

Brake retarders work by altering the engine’s operation to create resistance and help slow down the vehicle. There are different types of brake retarders, including exhaust brake retarders, compression brake retarders, and hydraulic retarders.

Exhaust Brake Retarders

Exhaust brake retarders work by restricting the flow of exhaust gases from the engine, creating back pressure. This back pressure helps to slow down the vehicle by reducing the engine’s power output. The exhaust brake retarder is typically controlled by a switch or a lever inside the vehicle, allowing the driver to engage or disengage the system as needed.

Compression Brake Retarders

Compression brake retarders, also known as “Jake brakes,” work by opening the exhaust valves at the top of the compression stroke. This releases the compressed air from the cylinders, creating resistance and slowing down the vehicle. Compression brake retarders are often used in diesel engines and are particularly effective at controlling the speed of heavy-duty vehicles.

Hydraulic Retarders

Hydraulic retarders use the vehicle’s transmission fluid to create resistance and slow down the vehicle. They work by redirecting the flow of transmission fluid through a series of chambers, which creates resistance and helps to control the speed of the vehicle. Hydraulic retarders are commonly used in heavy-duty vehicles and can provide precise speed control even on steep downhill grades.

Benefits of Using Brake Retarders

There are several benefits to using brake retarders in vehicles:

Improved Brake Life

By using brake retarders, the load on the vehicle’s brakes is reduced, resulting in less wear and tear on the brake pads and discs. This can extend the lifespan of the brakes and reduce maintenance costs.

Increased Safety

Brake retarders can help improve safety by providing additional braking power, especially when descending steep slopes or driving in slippery conditions. The added control and reduced reliance on traditional braking systems can help prevent accidents and improve overall vehicle stability.

Reduced Brake Fade

Brake fade occurs when the brakes become less effective due to overheating. By using brake retarders, the brakes are subjected to less heat and stress, reducing the likelihood of brake fade and maintaining optimal braking performance.

Fuel Efficiency

Brake retarders can contribute to fuel efficiency by reducing the need for constant braking and accelerating. By utilizing the engine’s power to slow down the vehicle, fuel consumption can be minimized, resulting in cost savings over time.


Brake retarders are valuable devices that provide additional control and safety while reducing wear and tear on the vehicle’s braking system. Whether it’s an exhaust brake retarder, compression brake retarder, or hydraulic retarder, these systems offer numerous benefits, including improved brake life, increased safety, reduced brake fade, and enhanced fuel efficiency. By understanding how brake retarders work and their advantages, vehicle owners can make informed decisions about incorporating these devices into their vehicles for an optimal driving experience.