Along the development process of gear units efficient software tools for design, calculation and simulation are in use. The applied systems, under it numerous expert tools of the Forschungsvereinigung Antriebstechnik e.V. (FVA) for design, calculation and simulation of various machine elements as well as CAD systems were operated mostly in isolation of each other. The geometrical- and functional development process was separated and the data exchange had to go to substantial parts manually. Today by the realization and standardization of a consistent product model for gear units the developer can fall back on a data-technical linkage of the different systems during the whole design process. As basis for the product model for gear units the international standard ISO 10303 STEP [1] (Standard for the Exchange of Product model data) is applied. STEP is used for the system-neutral product modelling and provides not only the complete geometry for data exchange, but also methods for other product data, like in this case calculation and simulation data of power train engineering. The product model of gear units was published in 7/2003 as VDMA-specification 23900 "Recommendation for a Product Model of Gear units". In the course of the national and international standardization the project was confirmed as value adding, because the abstract world of STEP has been adapted onto a specific product and an implementation is in use in companies of power train engineering. Due to these facts the standardization as a Technical Specification within ISO 10303-STEP is ongoing. The neutral model for the link of functional data to the geometrical product structure has generic character and is transferable to any other scope. With the demonstrated approach the usability for gear-units is proved and an extension to other parts and functional investigations will be promoted.