Safe, heart-pounding fun

September 13, 2021

They are an indispensable part of any amusement park. Riding on them is a fun activity for many, but for others, the mere sight of a roller coaster is enough to make them feel queasy. And with good reason: the world’s fastest roller coasters tear around the narrow tracks at top speeds in excess of 200 kilometers per hour. But even the slower rides comfortably reach speeds of over 100 km/h. These speeds give passengers a huge thrill and a surge of adrenaline.

Always on track

The undercarriage ensures that the cars stay safely on the tracks of these steel monsters. It generally consists of three pairs of wheels per axle: the running wheels, the side friction wheels and the up-stop wheels. The coasters are often configured with double wheels. The running wheels, which are the largest of the three, are what keep the train running on the rails. The guide wheels attached to the side of the train prevent it from derailing on twisty tracks. The up-stop wheels grip the rails from below, which keeps the coaster train grounded. Therefore, each car is fixed to the rails from all directions.

Withstanding the harshest conditions

The wheels of modern high speed roller coasters are subjected to huge forces, so they are equipped with tires made of polyurethane. Polyurethanes are extremely versatile elastomer materials that confer strength and durability to wheels for roller coasters, wheels for inline skates and golf balls, as well as other high-performance recreational equipment. Urethane materials are resistant to wear and abrasion as well as to cut and tear and heat buildup. Urethane systems from LANXESS are designed to withstand the harshest conditions and to provide exceptional dynamic properties for those applications. The special elastomers are sold under the brand names ADIPRENE^® and VIBRATHANE^® (urethane prepolymers) and ULTRALAST^® (urethane-based thermoplastic elastomers, TPUs).

Hot-cast polyurethanes can be formulated so as to absorb little energy during deformation and thereby only generate low levels of heat (low hysteresis). This prevents tires from heating up too much. Tire materials that generate less heat is better able to withstand high loads and speeds.

Higher load tolerances

Hot-cast polyurethanes are also advantageous in that they can be used to create harder elastomers. This means that they deform less than other elastomers under the same load. Heavy, repeated deformation can lead to the failure of lower hardness elastomers under high loads.

Michael Timm, Head of Marketing & Development, for the Urethane Systems business unit at LANXESS, explains that “the improved hysteresis and low energy loss mean that there is also lower rolling resistance, which is a crucial factor for wheels of both roller coasters and inline skates.”

All in all, the properties of cast polyurethane are an excellent match for the needs of the solid wheel market. Advances and improvements in cast polyurethanes have resulted in specialty, high value products that have even lower energy loss, higher abrasion resistance, cracking resistance, and high temperature performance, to meet the advanced needs of high performance wheel applications.

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