The invention relates to an operating material supply device for hydrodynamic components, for example, hydrodynamic switching elements for use in starting units, retarder assemblies or gearing assemblies. The material supply device includes an operating material reservoir arranged in the housing of the starting unit, retarder unit, or gearing assembly and comprises an operating material sump with at least one filling line that connects the operating material sump to the hydrodynamic component. The operating material sump may be closed in a pressure-tight manner.