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Exhaust Brake System

Exhaust Brake System

1. What is  Exhaust Brake ?

An exhaust brake is a means of slowing a diesel engine by closing off the exhaust path from the engine, causing the exhaust gases to be compressed in the exhaust manifold, and in the cylinder. Since the exhaust is being compressed, and there is no fuel being applied, the engine slows down the vehicle. The amount of negative torque generated is usually directly proportional to the back pressure of the engine.

Exhaust Brake System

An exhaust brake is a device that essentially creates a major restriction in the exhaust system, and creates substantial exhaust back pressure to retard engine speed and offer some supplemental braking. In most cases, an exhaust brake is so effective that it can slow a heavily loaded vehicle on a downgrade without ever applying the vehicle’s service brakes. Exhaust brakes are manufactured by many companies. The brakes vary in design, but essentially operate as described above. More advanced exhaust brakes have exhaust pressure modulation (EPM) that controls the back pressure which in turn improves the braking performance across a range of engine speeds.

Exhaust Brake System 1

2. Working principle of Exhaust Brake System

Essentially, it works by trapping engine pressure in the exhaust system, which in turn forces the engine to rotate slower (backpressure).

Normally, pistons travel upward in their cylinder bore to force spent exhaust gasses out of the engine via the exhaust valve. When the exhaust brake is applied and the inline butterfly valve is partially closed, significant additional force is required to push the spent exhaust from the engine. This additional force slows the engine’s rotational speed.  As the engine slows, the vehicle decelerates.

Exhaust Brake System 2

In some exhaust brake systems, the vehicle computer controls their operation. In others, the driver can manually actuate the exhaust brake. With either system, the mechanism which closes the butterfly valve may be powered by hydraulic pressure, air pressure or rely on an electronically operated servo motor.

Exhaust Brake System 3

3. Benefit of Exhaust Brake System

– Controls downhill vehicle speed

– Reduces brake heat

– Reduces brake wear

– A greater braking reserve for the conventional brake system

–  Completely silent

– Increased lifespan of normal brakes

4. Circuit diagrams of Exhaust brake System

Almost manufacturer car use Solenoid or Magnetic Valve on Exhaust Brake System. It usually has 2 wires, such as: Hyundai Trago D6CC 2014 and Isuzu NHR55

Exhaust Brake System 4

Exhaust Brake System 5

5. Location of Exhaust Brake System

An exhaust brake is typically mounted on the outlet side of the turbocharger and retards the engine’s ability to push out or exhaust compression

Exhaust Brake System

Exhaust Brake System


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