How does a diesel engine utilize engine braking if there is no throttle body to control air intake like in a gas engine?

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How does a diesel engine utilize engine braking if there is no throttle body to control air intake like in a gas engine?

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Is not the vacuum generated by the engine to do the work but compression in to the chambers

Jake brakes were never my specialty, and I haven’t worked on a diesel engine (or any engine, frankly) in almost a decade, but if I remember correctly it basically breaches the cylander at the point of compression so that the force goes out of the engine instead of transferring to the driveshaft. I’m possibly completely misremembering though, just putting myself out there to draw engagement and be corrected because I’m curious.

You basically turn off the fuel injectors so instead of adding fuel and making power in the cylinder which is sent to the wheels, the engine cylinder becomes an air compressor and “sucks” power away from the wheels, slowing the vehicle.

Modern diesel engines have a lot of things in the exhaust system to reduce emissions (turbochargers, exhaust gas recirculators, particle filters etc) which restrict the flow of gas through the exhaust and creates back pressure which adds some engine breaking effects.

Some engines also have an exhaust value to restrict exhaust flow to add more engine breaking, or jake breaks as another poster says.

If you drive an old diesel car, the engine braking is terrible / non-existent. Pretty much every modern diesel has a turbo that restricts the exhaust to provide some engine braking. Some trucks have specially designed turbos that adjust their vanes while braking, and redirect some exhaust back into the intake to increase engine braking. Others have a valve that blocks the exhaust pipe. I don’t think jake brakes are common on anything smaller than a class 7 truck.