A device for dividing a flow of lumpy material into two sub-flows comprises a dividing mechanism which comprises a dividing edge for splitting the material flow into two sub-flows, an apparatus for directing the material to the dividing mechanism and an apparatus for diverting the two sub-flows away from the dividing mechanism. The method includes determining a change in a combustion temperature rise within an engine based on a change in at least one engine operating parameter. The housing is designed such that it at least partly covers the gas bag towards the cover of the motor vehicle-based on the condition of the gas bag arrangement mounted in the vehicle.