As train operators increasingly focus on the total cost of ownership and lifetime value of their equipment, providers are developing their service and support offerings, says SKF’s STEVEN DICKSON
Relentless pressure to improve service levels while reducing operating costs is changing the way rail industry players think about their assets. Broadly, that shift entails a more holistic evaluation of the costs and benefits of the equipment and components they select for their fleets, one that balances initial investment, in-service performance, reliability, longevity and maintenance requirements.
This approach is helping to push up asset availability, while reducing the costs and downtime associated with both planned and unplanned maintenance. That benefits asset operators and their customers alike. It does create certain challenges, however. High performance components often need specialised installation, monitoring and maintenance procedures. That may require operators to acquire and retain new tools, skills and knowhow. But because those components may be designed to operate for extended periods between maintenance or replacement, those capabilities may be used only infrequently.
In response to this situation, component providers are evolving their own offerings to the industry, augmenting their traditional engineering and manufacturing capabilities with a broad range of service offerings that cover the full asset lifecycle.
Maintenance and overhaul
Take axle bearings and bearing units, for example. These parts have long formed the core of SKF’s rail industry product offering, and we have developed a number of highly sophisticated product solutions, including sensorised bearings that can provide real time information on speed, temperature and condition, and high efficiency, high longevity sealed bearing units with an operating life of 1.7 million km and beyond.
Today, SKF offers a number of specialised services to help customers manage their vehicle fleets and get maximum value from their bearings. Our railway bearing exchange service, for example, allows axle bearings to be swapped on site in a fraction of the time, and at a fraction of the cost, required to install a new wheel set. The service can be completed with no need to lift the vehicle. Instead, the body is jacked to allow the axlebox housing to be removed and our engineers use portable equipment to remove and replace bearings in only a few hours per wheel set.
Tapered bearing units (TBUs) removed from in-service rolling stock may have considerable service life remaining. SKF offers a dedicated refurbishment service for bearing units removed from customer vehicles. In the UK, that work is completed in our Luton Railway Service Centre, by experienced and qualified technicians.
TBUs are thoroughly cleaned in an environmentally friendly, water-based process. They are then dismantled, inspected and measured using purpose-made fixtures and measuring gauges. If the bearing is found to be fault-free, it is reassembled and axial clearance and float are checked, before the installation of new seals and high-quality lubricant of the correct grade to suit the customer’s application.
During the entire process, bearing components are kept together to prevent the accidental exchange of components between sets, and each unit is permanently marked with details of its refurbishment to enable full traceability. SKF stores a full information on each refurbishment in its own databases so customers can access service records at any time in the future simply by providing the appropriate TBU serial number.
Analysis and investigation
Increasingly, asset owners don’t just want bearings overhauled or replaced, they also want to learn more about the condition of those units. This might be to aid in the root-cause diagnosis of a premature failure, or as part of an effort to extend the service life of parts an optimise scheduled bearing replacement or re-lubrication intervals.
SKF supports its customers in these activities with a dedicated railway bearing investigation service. To evaluate the condition of a bearing, SKF engineers will take a grease sample from the unit as dismounted, and analyse the lubricant for evidence of degradation, water ingress or other contamination. The bearing will then be dismantled, cleaned and given a comprehensive visual inspection for evidence of wear, corrosion or damage. Digital photographs are taken to record the condition of the unit. If required, sections of the bearing are mounted and polished so the surface microstructure can be analysed. A comprehensive report will be provided to the client, outlining the findings of the analysis and indicating, where relevant, the probable cause of failure.
Since premature bearing failures are usually the result of an issue in the wider vehicle system and its operation or maintenance processes, SKF engineers can also work with our customers on on-site investigations to identify underlying root causes and propose modifications or upgrades to eliminate issues and improve overall system performance.
On-line condition monitoring
One of the most effective ways rail operators can boost reliability and vehicle availability while also reducing maintenance costs is through the adoption of condition-based maintenance techniques. Basic condition monitoring is already well-established in railway operations, for example through the use of track-side temperature measurement equipment to spot defective bearings in rolling stock.
In recent years, however, the measurement technologies and analytical techniques available to operators have advanced significantly. On-train monitoring systems, like the SKF IMx-R unit, for example, can record temperature, speed, load and vibration data from multiple train components. The realtime analysis of that data can be used to provide onboard warning of critical equipment failures, but these units can also transmit via GSM to a central facility where more sophisticated analytical techniques can be applied and the evolution of equipment condition over time can be tracked.
With the right algorithms and analytical expertise, these approaches help operators to spot developing problems early, allowing them to intervene where necessary to prevent failures and unscheduled downtime. With its extensive experience in the application of condition monitoring techniques to rotating equipment of all types, SKF works with rail industry OEMs and operators all over the world to specify and install appropriate monitoring equipment and to support the analysis of condition data from vehicles in service.