Engine braking is prohibited due noise from large diesels using compression brakes aka "jake brakes" - specialised engine braking hardware. They make engine br

Engine braking is prohibited due noise from large diesels using compression brakes aka "jake brakes" - specialised engine braking hardware. They make engine braking much more effective, so that trucks can slow down more without heating the regular brakes as much, but they can be loud. The parent is essentially right; engine braking is using the engine to slow the vehicle down.