NextSense’s Calipri Wheel system review

Whatever you might read in the papers, the rail industry has a first-rate reputation for safety. According to the Rail Safety & Standards Board, it is “1,500 times safer than motorcycling, over 500 times safer than walking and 30 times safer than travelling by car”. However, to maintain that standing, the industry must embrace new technology to stay at the forefront of passenger transport safety. Wheel measurement is not an issue in the public eye but that doesn’t make it any less important. It takes a significant amount of time to carry out wheel and brake disc measurements, as well as analysing the results.

As every engineer knows, each wheel has to be measured individually and this is, in many cases, still carried out manually with gauges. It’s normally a two-person job – one to measure, one to record the data – which can take several minutes for each wheel. And, where the wheelsets or brake discs are difficult to access, it can take even longer. On a standard 72-wheel vehicle, the whole process can take eight hours. Then there’s the need to accurately input the measurements on a computer for monitoring purposes. Again, this is time-consuming and prone to human error, potentially compromising accuracy and leaving the operating company open to risk.

A better process

Train operators are well aware of their safety responsibilities and the need to protect passengers, workforce and public. It is against this background that the Calipri Wheel system was developed by NextSense in Austria, a system for which Mechan became the sole supplier for the UK and Ireland in 2009. It is evident when you first trial the system that it was designed by a company that understands the problems associated with traditional measurement methods. NextSense has developed a system that provides a greater degree of accuracy, as well as a much simpler, quicker and more efficient process.

Calipri Wheel was designed to be as user-friendly as possible which is why it is popular with rail engineers internationally and is now starting to build its reputation here. One of the first priorities was to provide a system of automatic measurement, without the need for the engineer to make physical contact with the wheel or brake disk. This brings obvious benefits, making it much quicker and easier to take accurate measurements.

The system includes a laser sensor that can be moved by hand over the wheel or object to be measured. This takes about ten seconds during which it records segments of the wheel profile or object, and combines them to give an accurate picture of it. Also provided are acoustic feedback signals to support the user during the measurement process.

mehcan calipri wheel worker
Calipri Wheel takes around ten seconds to record segments of a wheel profile

Driving efficiency

Feedback from the industry suggested that train operators were looking for technology that meant wheel and brake disc profiling could be carried out by a single operator, making more efficient use of each engineer’s time. With the Calipri system, as soon as the entire profile line of the wheel has been recorded, the data is evaluated and the resulting measurement values are visible on its display. Any cases of given tolerances being exceeded are revealed immediately. This keeps downtime to a minimum and there is no need for data to be entered manually for later analysis. The sophisticated software means that these measurements can be stored and reviewed at regular intervals; they become an important part of the ongoing repair and maintenance schedule.

As well as measuring wheelsets, this type of technology can be used for many other applications such as brake disc inspection, clearance of the rail wheels, wheel diameter and defects, as well as wear inspection of rails and point switches. To make analysis and visualisation of the wheel profile even easier, the systems also have the option of Calipri Explorer, which enables the creation of individual reports of this type.

Carrying lots of different equipment is another drawback of traditional measurement methods. There was a very real need in the market for a multifunctional handheld device that can be carried by a single operator. Any engineer knows that conditions in the depot or on-track mean that measuring equipment needs to be durable to last the course. As a result, Calipri Wheel comes in a robust hardtop case with a foam insert to ensure the equipment is not easily damaged.

The optoelectronic gauge records geometrical data for any complex-shaped object and can be individually tailored by Mechan to the needs of each user. This was particularly important for Irish Rail, Calipri Wheel’s first customer. The fact that Ireland’s network has a wider gauge than the UK’s meant that its requirements were completely bespoke.

In fact, the train operator has its own manufacturing facility for wheelsets to suit the very specific needs of its rolling stock. As well as Irish Rail, a number of Calipri Wheel units are out on trial with other leading train operators and there has been really positive feedback to this sophisticated method of measurement.

mechan calipri wheel
The Calipri Wheel system

Bringing benefits to Irish Rail

It was on Mechan’s stand at Innotrans that Irish Rail first came across the Calipri Wheel system. The train operator had been looking at different options for upgrading its existing system of manual measurement and analysis. Chief Mechanical Engineer Peter Smyth welcomed the opportunity to try out the system and was delighted by it. “The first thing that struck me was that it was easy to use and that’s vitally important for any technology if you want it to save time,” he said.

Due to the track gauge issue, Peter was looking for a system that could be used to ensure production accuracy at the very tight tolerances required in their wheelset production process. He was also looking for it to form part of their ongoing maintenance schedule. Once Irish Rail had evaluated and understood the benefits, it placed an order for two wheel profile, diameter and clearance systems, becoming the first train operator in the UK and Ireland to do so.

Irish Rail wanted a system that would radically update its approach, providing a greater level of measurement accuracy whilst saving their engineers time. The mechanical gauges that Irish Rail had previously used meant logging details manually and then taking them back to the office to be entered separately onto a computer. Peter estimates that the new automatic system will be at least four times quicker, saving several hours every month. He liked the fact that their engineers wouldn’t have to touch the wheel to measure it and the system’s durability – well-suited to depot and on-track conditions.

Irish Rail had looked at a number of other systems on the market but didn’t find anything that was as simple to use or that met their requirements quite as well. As it operates over 600 vehicles across Ireland from its Dublin base, its engineers will receive full training from Mechan on the system to ensure they can use it to its full potential.

“Wheel safety is vital and this innovative new system will provide us with a much more effective method of maintaining high safety standards,” continues Peter Smyth, “which will mean we can more easily record and monitor wheel profiles. Because we will also be using it in our manufacturing plant, it will further enhance our abilities to meet the tight tolerances required in the wheel production process.”


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