Intelligent safety in roller coasters

Mr Stratmann, when roller coasters race along the rails at 100 kilometres per hour and more, enormous forces act on the body and the carriages. What role does your solution play in this?

Eike Stratmann: Our restraint systems ensure that the safety bars of the ride remain closed at all times. The hydraulic cylinders we have developed are so compact and strong that they are actually suitable for any type of roller coaster - i.e. classic rides, VR rides or even water roller coasters. With the LE-X restraint solution, we can use any type of seat, including shoulder, lap and belly restraints. We have been on the market with our systems for over 20 years and have actually been able to improve every aspect of the previous HLU LE 25 and 32 systems with the new version.

What are they?

Eike Stratmann: We have been able to significantly increase the service life from seven years to ten years or one million cycles for HLU LE-X (M) - whichever comes first - and two million cycles for HLU LE-X (E). The cylinder has been made even smaller, and a stroke of 80 to 250 millimetres is now possible - instead of up to 150 millimetres previously. In addition, the HLU LE-X (E)'s advanced sensor technology means that we can now offer detailed data analysis and predictive maintenance at the latest state of the art. igus® has been an important development partner from the very beginning.

Julian Liebsch: Exactly, we were brought on board by HAWE very early on in the development process of the spindle assembly that is central to the HLU LE-X (E). It was a great advantage that HAWE was very transparent and always provided us with a lot of information. We then quickly realised that our dryspin® thread technology was the right solution for the locking system. We use lead screw nuts made from our lubrication-free, maintenance-free and wear-resistant high-performance plastics. The specifications and geometries of our lead screw technology with dryspin® technology, which are matched to the plastic nut and spindle, guarantee efficiency levels of up to 82 per cent and a service life that is up to 30 per cent longer than conventional screw drives.

Mr Stratmann, why did you choose igus® ?

Eike Stratmann: Quite simply, with its lead screw technology, igus® fulfilled all our requirements in terms of validation. As already mentioned, one of the core requirements of our customers during development was an improved service life. We applied 12 million load cycles to the spindle assembly of the HLU LE-X (E) and it lasted. That convinced us. What's more, igus® provided us with calculations and the relevant values throughout.

The decision was ultimately made in favour of the dryspin® lead screw technology and the iglidur® J material. Why?

Julian Liebsch: The original requirement was that the material should be able to withstand one million cycles. For this reason, we initially decided in favour of the material iglidur® E7 for the lead screw nut. As a soft, vibration-damping material, it is ideal for these conditions. The first tests there already showed that we can run over ten million cycles without wear. As the project progressed, the threaded nut geometry was adapted again by HAWE and a male thread was added. In order to continue to guarantee the necessary strength, we finally decided to use our versatile endurance runner iglidur® J for the threaded nut material. The required running performance was no problem at all here either.

Eike Stratmann: " This experience was very valuable for us. avoiding abrasion is incredibly important in our closed hydraulic circuit in the cylinders. abrasion in the system harbours the risk that the safety valve cannot close properly and, in the worst case, the extender crossbar could open while driving. With iglidur® J, we can now be sure that the extender crossbar remains closed at all times.

Intelligent data processing has long since found its way not only into industry, but also into roller coasters. How do amusement parks benefit from this?

Eike Stratmann: The HLU LE-X (E) locking system is equipped with very detailed data acquisition. Status data is stored in the electronics, which is later analysed in the cloud with the help of artificial intelligence. The algorithms then calculate a predicted replacement date long before a failure is actually imminent. One value, for example, is the tightness of the cylinder: a limit value is already written to the electronics during production. If a limit value is actually exceeded, the user is immediately notified on the computer after the data upload. The status data is visualised in a clear dashboard. This naturally reduces the workload of the staff on site, as a large number of time-consuming inspections are no longer necessary. It's exactly the same in amusement parks. There is currently a weekly inspection in the parks. This means that once a week, the mechanic has to check each locking system of a seat with a special pre-tensioning device that checks the cylinder tightness. The cylinder works if it does not give way. With the sensor technology in the LE-X, we can check this automatically so that a pre-tensioning device is no longer necessary. The manual test with two cylinders per seat takes about ten minutes. With the large number of seats and many different rides in amusement parks, the mechanics save a lot of time.