Exhaust brake

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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.

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. 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.