When an engine brake is actuated on a current truck diesel engine, what is the maximum fueling permitted?

When an engine brake is actuated on a current truck diesel engine, the maximum fueling permitted is no fuel. This is because when the engine brake is engaged, the primary function is to use the engine’s compression to slow the vehicle down rather than relying on the throttle to provide additional power. In this mode, the intention is to maximize braking effect and minimize any thrust that could counteract the braking force.

By restricting fuel delivery to zero, the engine essentially functions as an air compressor rather than as a power-producing unit. This not only helps in decelerating the vehicle effectively but also minimizes wear on the engine components since higher fueling rates while braking could lead to increased emissions and overheating.