The continuous braking limiter (DBL) is a safety system which makes it impossible to improperly disengage the drive system by stepping on the clutch, for example when driving downhill. The continuous braking limiter constantly monitors the legal speed limit of the vehicle. If the vehicle exceeds this limit, such as when driving downhill, the continuous braking limiter communicates with the other safety systems. First the fuel injection to the engine is interrupted, and if further action is required, the retarder, the wear-free auxiliary brake, is activated. This improves safety on sections of road with steep downhill gradients and makes it impossible to accidentally exceed the speed limit in cases when this could otherwise rapidly occur.