Staying on track

When it comes to polyurethane wheels, few applications are as demanding and as critical as roller coaster wheels. Here, Capa™ can help improve durability.

What demands are placed on roller coaster wheels?

A typical roller coaster travels at around 100–150 km/h, with increasing pressures and forces exerted on the wheels. The internal temperature of the wheels will increase towards 40 to 60°C as it rolls around the track. The wheels need to maintain their dimensional stability as the temperature increases. This is an application that simply cannot fail, so wheels need to over perform throughout their lifetime.

What difference can Capa™ make?

Capa™ offers a combination of very good dynamic properties and abrasion resistance. When used in the formulation of polyurethane wheels, it will help dissipate heat better than conventional polyurethane systems and ensure the wheels maintain its shape. It will also make sure that the wheels do not wear away as quickly, which means less maintenance and downtime. In fact, wheels made from Capa™ can last up to twice as long as conventional systems.

What specific grade would you recommend for a roller coaster wheel?

The best option would be either one of Perstorp’s standard homopolymers of 2000 molecular weight; or a copolymer, which is a combination of caprolactone and PTMG (polytetramethylene glycol). The first option offers good dynamic performance, high load-bearing properties and good abrasion resistance. Even if there is low friction between the wheel and metal track, the higher temperatures will make abrasion worse. The second option offers a wider operating temperature range and good performance at low temperatures, as well as the durability properties mentioned above. This can be important, as the wheels could be cold in some parts of the world at the start of operations and cracking can be a problem at cold temperatures.

Can Capa™ be used in wheels and rollers for other applications?

Roller coasters probably have the highest demands when it comes to polyurethane wheels, but this is a small niche area in the market. At the other end of the spectrum, you have other applications such as industrial trolleys and fork-lifts to skateboards and rollers in printers. Then there are higher performance applications, such as

industrial machines where rollers are used to transport products at a faster and faster pace.

Does Capa™ contribute the same benefits in these applications?

It still comes down to durability. As production units maximise productivity and aim to get the most out of their machines, rollers are running faster and harder. Every second that a machine is down to enable a worn-out roller to be changed will cost the operator money. If a roller can last longer, this means less maintenance and higher productivity, which will ultimately reduce the overall cost of the operation.