With wheelset and bogie service Fit for 55

The maintenance of wheelsets and bogies is of crucial importance for the safety, efficiency and cost-effectiveness of rail transportation. In addition, refurbishing these components in accordance with the latest technological standards extends the service life of vehicles and rail infrastructure alike, thereby reducing the overall environmental impact of the rail system.

Why reprocessing and revision?
Refurbishing wheelsets and bogies is cheaper than buying new ones. Regular inspections and retrofits minimize downtimes, and vehicles are available again more quickly. The targeted repair of components and the resulting recyclability enable operators to make considerable savings. This form of “upcycling” also makes a significant contribution to climate protection on the railways. The term “Fit for 55” refers to the European Union’s goal of reducing net greenhouse gas emissions by at least 55% by 2030 as part of the climate protection package. Refurbishment and maintenance help to reduce the carbon footprint, as fewer new components are manufactured and resource consumption is reduced accordingly. The increased demand for the revision of wheelsets and bogies reflects these developments and is seen as a positive trend in rail transportation. Certified service workshops play a key role in ensuring the sustainability of the system.

Center for wheelsets and bogies
The merger of the Robel Service & Customer Service division with Deutsche Plasser to form Plasser Robel Services (PRS) also involved restructuring in the area of wheelset and bogie services. In order to meet the volume of demand and the increasing normative requirements, a separate competence center in value stream design (Fig. 1) for wheelsets and bogies (KRD) was established at the PRS site in Freilassing, Bavaria. On a production area of 3000 m², around 30 employees currently work according to the 5S standard in process-optimized cycle production. In 2022, 130 bogies and 1,300 wheelsets were refurbished, and the center has also been producing new bogies for Robel since 2023. The synchronized process in the new hall is designed for future growth: The capacities enable the annual throughput of up to 2500 wheelsets and 250 bogies, regardless of brand and manufacturer.

Environmental management at the Freilassing site
In addition to the business division’s contribution to climate protection through upcycling instead of disposal, the focus is also on operational environmental protection measures on the factory premises. An important step in this context was the complete modernization of the wheelset and bogie hall.

The KRD’s entire electricity consumption is covered by green electricity, and the proportion of renewable heat generation is around 80 %. Modified production processes and the energy-efficient equipment in the assembly hall contribute to significant savings in electricity consumption. In addition, specific investments such as the procurement of a glass bead blasting system for cleaning components not only lead to significantly reduced dust and noise emissions, but also to state-of-the-art waste management in production operations. Another investment in the area of environmental management is the comprehensive warehousing of the service center. An average of 800 wheel disks and 100 axle shafts as well as wear parts, gear wheels and housings of all Robel and Plasser & Theurer types are stored in Freilassing. This allows a quick response even for orders at short notice, e.g. in the context of accident repairs. Robel is currently building a new logistics center for the provision of parts, which will go into operation at the end of 2024, in order to further develop the warehouse processes in a resource-saving and ecological manner. The aim is to significantly streamline processes through automated workflows, accompanied by further CO₂ reductions, additionally supported by photovoltaic systems and green spaces on the roof of the building.

Overhaul of wheelsets and bogies in cycle production
The redesign of the assembly hall from the ground up enabled the installation of state-of-the-art process logistics from delivery, cleaning, disassembly and reconditioning through to special test benches at all stages of production. Wheelsets and bogies pass through the hall in two spatially separated processes (Fig. 2). The average lead time for running axles is currently four weeks, six weeks for drive axles and eight weeks for bogies. Carrying out all important processes at one location, including non-destructive testing and welding, reduces transportation routes, speeds up reconditioning and increases availability for customers. The KRD’s European certifications (see info box) and the certified expertise of the specialist staff guarantee safety in the critical wheel-rail contact. All reconditioning and testing steps are documented in accordance with standards. This ensures the seamless tracking and quality control required for approval.

Process example for the reconditioning of bogies

Delivery
The customer shall deliver the bogie and/or the wheelsets to the Freilassing plant on the agreed date. Unloading is carried out by PRS. Experts check the delivered components and compare them with the order. This step ensures that all the necessary parts are available and that the process can continue smoothly.

Cleaning the components
To ensure clean dismantling, the components are pre-cleaned using steam blasting before being made available in the hall, and the dirty water is separated via oil separators and disposed of properly.

Disassembly and visual inspection incl. Untying the wheelsets
Certified visual inspectors record damage or indications of damaged areas, in particular paint flaking, visible deformations, etc., which are later examined in more detail after paint stripping or disassembly. In addition, a photo documentation of the delivery condition is made. All components are marked to ensure that they can be assembled later. The wheelsets are removed from the bogie and transferred to a separate reconditioning process (cycle production in a separate area). This includes dismantling the axle bearing, pressing off the wheel disks using a wheelset press (Fig. 3) and opening the gearbox.

Dismantling the bogie frame
Depending on the scope of the refurbishment, all add-on parts, brake components etc. are dismantled down to the base frame and prepared for the removal of the corrosion protection required by the standards. Alternatively, the frame is partially dismantled to check for damage and cracks in its painted state.

Certified test center for non-destructive testing (ZfP)
PRS operates its own certified NDT test center in accordance with DIN 27201-7 NDT Railways. The test centre is based on an independent test organization structure with certified testers according to DIN EN ISO 9712 in the industrial sector IS (new production) and railroad sector IrW (maintenance/repair) for the following test methods: VT – visual testing (DIN EN 13018), PT – penetrant testing (DIN EN ISO 3452-1), MT – magnetic particle testing manual/partially mechanized (DIN EN ISO 9934-1), UT/PAUT – conventional and phased array ultrasonic testing (DIN EN ISO 16810). The in-house competence center creates, verifies and validates customer-specific test instructions and plans. The NDT test bench was developed in the company and enables the longitudinal bore to be tested as a new additional service. The bore of the complete wheelset shaft is scanned using an ultrasonic test lance (Fig. 4), and a sonic curve plan regulates the intervention limit. Depending on the scope, a visual inspection is carried out in painted or unpainted condition or a magnetic particle inspection in unpainted condition. If there are signs of defects on the bogie, repair welding is carried out by certified welders in accordance with DIN EN 15085-2. Deviations in the frame are measured using a 3D measuring arm, parameters such as distortion and wear are evaluated and rectified accordingly.

Reconditioning the add-on parts
All add-on parts of the bogie and wheelset are stripped of paint and refurbished. Some of these, such as brake cylinders and brake calipers, are sent to certified subcontractors for further processing. The hydraulic cylinders are fully reconditioned at KRD: Replacement of seals and wear parts as well as leak testing, disassembly of the block brake system, replacement of wear parts and inspection of all bolts. Coil springs are tested and recorded on the spring test bench for reusability in accordance with the Association of Freight Wagon Keepers in Germany (VPI). Since 2024, PRS has also been offering the reconditioning of cartridge bearings (Fig. 5), a further step towards sustainability. The company already has the necessary certification from the French SNCF, and the corresponding accreditation from Deutsche Bahn AG (DB) is in preparation. In-house bearing reconditioning shortens throughput times and allows faster assessment of the complete wheelset condition. There is no need to send the bearings for external reconditioning; the customer receives the original bearings in documented quality. The inspection of the bearings also allows conclusions to be drawn about irregularities such as the condition of the bearing grease and the rolling elements, which are passed on to the operator for optimization purposes.

Varnishing
The bogies, wheelsets and add-on parts are coated on the factory premises in an environmentally certified painting center in accordance with the standard-approved paint structure. In the medium term, PRS plans to blast the components in-house and expand the painting center in order to increase quality and reduce throughput times through internal processing and control.

Final assembly
All prepared and painted add-on parts are mounted on the bogie frame and hydraulic and pneumatic lines are installed. Now comes the “marriage”, the fitting of the frame onto the overhauled wheelsets and the attachment of all connecting and fastening elements.

Bogie test stand / outgoing inspection
The bogie test stand installed in 2022 (Fig. 6) records all parameters in accordance with DIN 25043-7 for testing and adjusting wheel loads and bogie geometry (Table 1). Correct adjustment is required by standards and minimizes wear and thus the operating costs of rails and rolling stock. Precise testing is also essential to ensure operational and derailment safety. Adopting this test procedure as a service enables the vehicle owner to use the standardized reconditioned bogies straight away. The test stand can also be used for streetcar bogies, traction units and mainline rail cars.

Extending machine service life with a comprehensive service package
A showcase project in terms of sustainability and maintenance expertise is the bogie refurbishment of maintenance vehicles for class 708.3 overhead lines from old GDR stock (Fig. 7). Due to the reliability of the machines and the long approval process for new purchases, the customer decided to overhaul the existing bogies so that the vehicles could continue to be used. The challenge included checking and transferring the more than 30-year-old original drawings and technical documents for the procurement of spare parts – a service that was completely taken over by PRS. The company also invested in its own bogie test bench in order to be able to carry out the standardized reconditioning in accordance with the specifications. Since the start of the project in 2021, 14 bogies have been overhauled and a further ten will be completed by the end of 2025.

A building block on the way to Fit for 55
The reconditioning of wheelsets and bogies helps to extend the service life of vehicles, increase their safety and efficiency, conserve resources and shape the future of rail mobility sustainably through the use of intelligent technologies. With ongoing investments in processes, systems and testing procedures for the upcycling of existing components, KRD in Freilassing is setting standards in the field of environmental and climate protection for the rail system.