INTERNATIONAL Technology Internationales Verkehrswesen (74) 1 | 2022 40 Modular platform concept for shunting locomotives Sustainable vehicle architectures for existing vehicles through modularity Shunting, Modularity, Vehicle platform, Rail freight, Sustainability, Efficiency Rail freight vehicles are long-lived and enormously varied. This applies especially to shunting locomotives. Shunting locomotives on the market have an interwoven and interface-rich architecture. On the other hand, there is the discussion about cost efficiency and sustainability. This paper therefore presents a modular platform concept for the sustainable modernization of vehicles. Julian Franzen, Jannis Sinnemann, Udo Pinders, Walter Schreiber R ail transport is seen as the key to sustainable freight transport. Nevertheless, diesel-powered vehicles are predominantly used for shunting and the last mile. The vehicles used for this purpose are put under economic constraints due to tight budgets and the need for economy. As a result, life cycle cost optimization and digitalization approaches are more and more increasing. Innovations are gradually finding their way into research and the market, although mainly for new vehicles. Following on from current sustainability discussions, sustainable and green traction concepts for shunting vehicles are also coming into focus. While green traction technologies are currently not available in a market-ready solution, they are potentially available in a few years. In summary, maintainability, digitalization and sustainability of shunting vehicles will be the key boundary conditions for vehicle architectures in the coming years. State of the art and current challenges There are various types of shunting vehicles with two to four axles, depending on the intended use. All different types have the same basic structure. In principle, the structure of a locomotive can be divided into the running gear (wheelsets, bogies, brake components), the vehicle frame with buffers and the superstructures. The superstructures include the drive train, the brake frame, the auxiliary equipment, the driver’s cab and control components [1]. Currently, the development of shunting vehicles is mostly based on function fulfillment, i.e. the provision of traction to fulfill the transport task. The results are vehicle architectures with interwoven, complicated and interface-rich arrangements of vehicle components. This fact has a negative impact on the maintainability of the vehicle because it results in high workloads and therefore in financial expenses as well as downtimes. At the same time, there are many variants of vehicles in stock. This diversity results from different vehicle configurations delivered by the manufacturer and replacements made during maintenance and modernization. Due to the long life of shunting locomotives, modernizations of existing vehicles are often advantageous from a commercial point of view compared to the acquisition of new vehicles, resulting in the existence of further modernized variants [2]. From the point of view of maintainability, the large number of variants, which is favored by inadequate documentation of modifications, means that maintenance work has the character of a single project and economies of scale cannot be exploited. Furthermore, shunting vehicles have hardly been digitally integrated into value chains to date [3]. Due to the diversity of the individual vehicles (even of the same series), digitalization efforts, e.g. IoT solutions for component monitoring, have a high individual project character and are accordingly not scalable. Moreover, methods, e.g. for predicting component states, are based on reference data. This data cannot be provided due to the lack of data availability and thus prevent the application of such methods. Typically, shunting vehicles are currently equipped with diesel engines. Even if railway-specific engines comply with emission limits, alternative forms of traction are increasingly attracting the interest of operators [2]. With current vehicle architectures, the integration of modern diesel engines represents a common modernization at reasonable cost. Alternative topologies based on accumulators, fuel cells or the combustion of hydrogen in diesel engines cannot be integrated into existing vehicles, or only at unacceptable expense, due to completely different operational and spatial requirements. The state of the art, outlined for vehicle architectures of existing vehicles, is therefore not open to overarching concepts that consider maintainability, digitization and sustainability. Modularity as an enabler The previously mentioned challenges result in new requirements for vehicle architectures of both existing and new vehicles. Due to changing operational and legal requirements, the flexibility of vehicle architectures is becoming more important. A further challenge for the cost-efficient, sustainable operation and maintenance of an existing vehicle is the management of the diversity of variants. Only when vehicles become comparable from a maintenance perspective, economies of scale can be activated to save costs and increase benefits. In this context, the methodical modularization of the vehicle structure represents a promising approach. Rail vehicles are complex technical systems consisting of many components with interdependencies. By definition, the concept of modularity addresses the state of a system in which dependencies Technology INTERNATIONAL Internationales Verkehrswesen (74) 1 | 2022 41 between the individual components of a system are kept low and component interactions take place via unified interfaces [4]. This can be seen as the opposite of the current state of the art for structures of existing shunting vehicles. Figure 1 shows the methodical modularization of the locomotive structure to create an open vehicle platform. Starting from a target system (e. g. a shunting locomotive that has to be modernized due to its age), modularization is carried out in compliance with the usual process specifications (RAMS, CSM-VO according to EU/ 402/ 2013, DIN EN 50126 ff.) to ensure functional safety by first identifying the essential (safety relevant) functions of the target system (e.g. providing traction). Based on these, individual functions are identified in the next development step that are necessary to fulfill the main functions (e. g., increasing the motor speed, filling the flow transmission, controlling the traction motors, etc. to provide traction). The preparation of the overall structure is done with respect to modularity by forming assemblies, which in turn may consist of one or more components and are used to perform a single function. These assemblies are separated from one another in terms of mechanics, energy and signaling, and are connected to one another by defined interfaces. Thus, assemblies can be subjected separately to a safety assessment to promote interchangeability within the framework of the modular principle. The overall system architecture finally results from the arrangement of the assemblies on the vehicle, considering safety, approval and operation requirements. If the project is successfully implemented, approved and tested, the concept is standardized and becomes part of the standardized vehicle platform. The existing vehicle platform is the starting point for the realization of individual customer requirements, which are integrated into the existing standard. This can involve replacing individual components and assemblies (e. g. the engine module with a different performance class) or adding (software) modules to implement individual safety and non-safety-related functions. In addition, the modular architecture allows to implement alternative drive topologies within an acceptable cost framework thanks to economies of scale. However, the core of the implementation remains the approvable standard of the platform locomotive. Realization and advantages of the platform locomotive The Westfälische Lokomotiv-Fabrik Reuschling applies the modular vehicle platform for the modernization of dieselhydraulic shunting vehicles. In the process, the vehicle structure of an existing vehicle is designed in the course of updating the technical structure from the point of view of a modular standard. Figure 2 shows the model of an existing modernization standard for the LHB 530C series. As can be seen from the model, there is a consistent separation of the most important components and assemblies of the superstructure in separate frames and carriages. This achieves a flexibility that not only affects maintainability, as explained in more detail in the following section, but also operational processes. For example, hoods that are easy to dismantle can significantly reduce the complexity of the transport of shunting locomotives to operating locations by road, because the vehicle does not have an oversize body. In this way, costs can be reduced and processes be streamlined. The use of the modular principle to realize individual customer requirements affects not only the design but also the control unit of the vehicle. The control and software architecture of the platform locomotive is also modular in design, so that once modules have been replaced or substituted, there is no need to go through a complete software approval process; instead, all that is required is an examination of the module involved, its interfaces and the impact on the overall system. Vehicle structures based on the modular principle have many advantages. These are presented below in more detail but not exhaustive for the aspects of maintainability, digitization and alternative drives. Maintainability Mechanically, the use of quick-release fasteners to attach the individual modules to the vehicle frame and the storage of components on slides greatly accelerates maintainability and interchangeability. Due to the modular design and better accessibility, times for troubleshooting can be significantly reduced. In extreme cases, modules can be exchanged with identical ones. As a result, downtimes and costs are reduced because disassembly activities, waiting times for services or components are reduced and operational capability can be restored more quickly. An example of mounting a compressor on a carriage for simplified maintainability is shown in figure- 3. By pulling the carriage out, the component can, in contrast to current state of the art architectures, be quickly and easily maintained. The concept also allows procurement to be extended to related, e.g. automotive, suppliers. For example, truck engines of suitable performance classes can be used as part of the platform concept, with exhaust gas standards, lower procurement prices and times, larger quantities, and a highly available maintenance network. Overall, life cycle Figure 1: Procedure for modularization and creation of a standardized vehicle platform Figure 2: CAD drawing of a shunting locomotive modernized according to the modular concept (LHB 530C) INTERNATIONAL Technology Internationales Verkehrswesen (74) 1 | 2022 42 costs can thus be consistently reduced in the realization phase, but especially during use and maintenance. Digitalization As shunting vehicles are increasingly integrated into the operator’s IT infrastructure, the vehicles require appropriate infrastructure and connectivity. The IT infrastructure on vehicles ranges from simple localization sensors (GPS) to decentralized computing capacities for data evaluation, for example for condition monitoring. Furthermore, a decentralized control periphery is implemented on the vehicle. This means that modules are connected to the central control unit via a common link, e.g. Profinet, and components are not wired separately, as it was previously the case. This means that only one instead of several signal cables are required per module, which reduces the amount of cabling, required space and potential errors e.g. due to line damage. Lastly, data availability is guaranteed and the flexibility of the data infrastructure on the vehicle is ensured in order to make replacements or extensions, e.g. for the application of artificial intelligence methods. Sustainability As described previously, the vehicle platform allows drive trains to be considered with a large degree of freedom. Currently, diesel-hydraulic drives are predominantly implemented for shunting vehicles. Using advanced engine technology, these are characterized by reduced emissions and lower consumption (up to 50 % fuel savings compared to existing engines) with the same or higher performance. In the near future, as shown by initial feasibility studies conducted by numerous operators, alternative drive technologies will additionally influence the decision-making space in modernization projects of shunting vehicles. While alternative combustion drives, e.g. gas engines, can be integrated into existing standards due to their similarity to existing solutions, the challenge for green hydrogen-based drives is much more challenging due to storage and refueling. Accordingly, different powertrains can be expected due to different energy conversion processes with different spatial as well as safety requirements. While it does not seem realistic to integrate hydrogen-based drive solutions into state-of-the-art vehicle bodies, the platform concept provides a suitable basis for the realization of such concepts. However, due to the long decision-making cycles, it is important to prepare architectures for corresponding solutions now. Conclusion To date, the concept described for modularizing the vehicle architecture has been implemented for ten shunting locomotives and further vehicles are currently being retrofitted. Modularization of vehicle architectures is also regularly used in some cases, e.g., for remotorization. Observations and experience gained in practice have confirmed the advantages of modularity for maintainability. In the area of digitalization, the decentralized and modular control architecture provides a resilient basis for vehicle control and diagnostics. In addition, it has already been possible to implement sophisticated digitalization projects using the platform concept (see e. g. a3-Lok [5] and RangierTerminal 4.0 [6]). The integration of alternative drive technologies will most clearly shape the further development of the platform concept in the coming years, especially for existing vehicles. The combination of different sustainable energy supplies on the vehicle (hydrogen combustion, fuel cell, battery) in conjunction with their respective novelty poses technical problems for the platform concept on the one hand, because fundamentally different boundary conditions exist with regard to spatial arrangements, interactions and signal and material flows. Apart from the technical functionality, the legal, social and economic constraints of alternative drive technologies also determine the design of a sustainable vehicle platform. Even if the first pilot applications for very limited use cases will appear in the near future, the development of a marketable vehicle platform for sustainable drive topologies will initially be in the focus of research and development due to the issues to be solved. Nevertheless, Westfälische Lokomotiv-Fabrik Reuschling considers the development of a suitable platform concept to be without alternative for seriously achieving sustainability and zero emission targets. ■ LITERATURE [1] Janicki, J.; Reinhard, H.; Rüffer, M. (2020): Schienenfahrzeugtechnik. [2] Höft, U. (2016): Mehr Güter auf die Schiene, aber wie? Ansätze und Vorschläge zur Attraktivitätssteigerung des Schienengüterverkehrs. Gutachten für die Fraktion Bündnis 90/ Die Grünen im Deutschen Bundestag. [3] Müller, S.; Lobig, A.; Liedtke, G. (2016): Chancen und Barrieren für Innovationen im deutschen Schienengüterverkehr: Eine innovationstheoretische Perspektive. In: Zeitschrift für Verkehrswissenschaft 87 (3), S. 177-206. [4] Magee, C.; Weck, O. (2004): Complex System Classification. In: INCOSE International Symposium 14 (1), S. 471-488. [5] Geischberger, J.; Falgenhauer, R.; Hanisch, R.; Franzen, J.; Grunwald, A. (2021): RangierTerminal4.0: Automatisiertes Rangieren im JadeWeserPort . In: Der Eisenbahningenieur 12/ 2021, S. 43-46. [6] Franzen, J.; Lingen, M.; Pinders, U.; Kuhlenkötter, B. (2019): Reduction of system-level lifecycle costs through movement-based operation adjustment for railway vehicles. In: Proceedings of the 12th World Conference on Railway Research. Figure 3: Better accessibility of components e.g. by mounting on slides for better troubleshooting and maintainability Jannis Sinnemann, Dr.-Ing. Innovation Manager, Westfälische Lokomotiv-Fabrik Reuschling GmbH & Co. KG, Hattingen (DE) j.sinnemann@reuschling.de Udo Pinders, Dipl.-Ing. Dipl.-Wirt.-Ing. CEO and Shareholder, Westfälische Lokomotiv-Fabrik Reuschling GmbH & Co. KG, Hattingen (DE) u.pinders@reuschling.de Julian Franzen, Dr.-Ing. Head of Innovation, Westfälische Lokomotiv-Fabrik Reuschling GmbH & Co. KG, Hattingen (DE) j.franzen@reuschling.de Walter Schreiber, Dipl.-Ing. Management Board and Shareholder, Westfälische Lokomotiv-Fabrik Reuschling GmbH & Co. KG, Hattingen (DE) w.schreiber@reuschling.de