How Exhaust Brakes Work


What is an Exhaust Brake?

An exhaust brake is a device used to control vehicle speeds and decrease stopping distances, especially while towing. They are attached to the truck's exhaust system and use backpressure to effectively use the engine to help slow a vehicle and maintain safe speeds while decending grades.


How does an Exhaust Brake Work?

The main components of an exhaust brake are the housing, butterfly valve, and actuator. An exhaust brake is typically mounted behind the turbocharger, but may be installed further down the exhaust stream when space is limited. There are several styles of exhaust brakes unique to their respective manufacturer, however the operation concepts are the same in all cases. An actuator is attached to the butterfly valve inside the brake housing. In the open position, the truck operates normally and the opened valve does not cause any significant increases in exhaust backpressure. When the exhaust brake is engaged, the actuator closes the valve, forcing exhaust gases through a small opening and therefore increasing exhaust backpressure. This backpressure works against the engine's pistons and causes the engine to slow down. On new trucks, the exhaust valve is controlled by the engine's computer and has the ability to operate in varying positions depending on driving conditions. The exhaust valve will only close when the driver has released the throttle. For the exhaust brake to function, the truck must be in gear w/ the clutch engaged (manual trans) or in gear with the torque converter locked (auto trans). The concept of an exhaust brake is similar to an engine brake in that they both are using the engine to slow the truck.



Benefits of Using Exhaust Brakes:

Exhaust brakes well worth the investment if you find yourself towing often or towing extremely heavy items, especially in mountainous terrain. Drivers will experience decreased stopping distances, increased brake pad/shoe life, and increased safety descending long, steep grades.



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