HR Wallingford Improves its Wave-making Systems with Rollon’s Compact Rail Plus

HR Wallingford, a UK-based specialist in hydraulic research and wave-making systems, needed a reliable linear motion solution to improve the precision, durability and flexibility of their piston-type wavemakers. By adopting Rollon’s Compact Rail Plus with zinc-nickel coating and marine-grade grease, HR Wallingford achieved higher load capacity, reduced maintenance, easier installation, and consistent accuracy under challenging conditions.

Water is certainly a force to be reckoned with. Its unpredictability and power cannot be overlooked when building structures or studying their resilience. So, understanding how it moves, behaves and influences communities and industries is pivotal to developing lasting engineering solutions.

This is precisely the field in which HR Wallingford excels. Founded in the late 1940s as a government-owned organisation dedicated to research in coastal protection, this UK-based company has since become a global reference in hydraulic modelling. Traditionally, this meant creating and testing physical scale models of civil engineering structures such as breakwaters or harbour quays to understand how they resisted different wave conditions. Today, HR Wallingford continues this legacy by delivering advanced solutions that help research centres better understand the changing impact of water where it interfaces with both natural and built environments.

“Understanding the changing impact and influence of water in natural and built environments is essential to our future wellbeing,” explains Tom Matthews, Project Technician at HR Wallingford. The company’s Equipment & Technology Group, which began designing these systems over three decades ago, now includes around 40 experts supplying piston and hinge flap wavemakers to research facilities worldwide. These systems allow engineers and scientists to accurately replicate wave conditions within a physical model and study their impact with remarkable precision.

Challenges of the application

The operational regime and environmental conditions are challenging. Furthermore, the system needs flexibility to adapt to different machine designs, high durability, and precise motion at relatively high speeds.

Another factor is the variability of the loads applied by waves. “We generate both regular and irregular waves. Regular waves produce repeated cyclic strokes, while irregular waves are based on real sea states built up from a spectrum of sizes and frequencies. It’s with the irregular waves – especially those with high frequencies – that we’ve seen the highest and most abrupt load changes,” Matthews explains. Meeting this demand requires a robust and adaptable linear solution.

The Rollon solution

Rollon engineers supplied the Compact Rail Plus linear guide, designed for high loads, precision, and durability. This linear solution features cold-drawn carbon steel profiles with induction hardened and ground raceways, enhanced by a zinc-nickel coating designed to protect against corrosion.

Rollon® Compact Rail Plus linear guide.

“For this challenging environment, we also applied a special grease resistant to water washout,” explains Timothy Prinsloo, Technical Sales Engineer at Rollon.

The system was delivered as a pre-assembled kit, with sliders configured in orientations tailored to absorb the forces generated by waves. “This, together with the HR Wallingford wavemaker actuator design, simplified manufacturing and maintenance. The installation is straightforward and repeatable,” adds Prinsloo.

Advantages of the solution

With Compact Rail Plus, HR Wallingford achieved the flexibility and reliability they needed.

“Rollon adjusts the bearings directly in the factory, so we can send them straight to our fabricators. Previously, they would spend one or two days fine-tuning adjustments, especially on larger multi-axis machines. Now, the components arrive ready to install, with higher load capacity than what we had before,” says Matthews.

The benefits are not limited to assembly. Reduced maintenance and improved reliability also translate into reduced operational cost savings through a significant increase to the operational durations between maintenance inspections. “Many of our products are shipped worldwide. If bearings loosen in the field, a repair trip can be extremely expensive. Compact Rail Plus significantly reduces this risk,” Matthews adds.

Performance was equally critical. The system enabled speeds of up to one metre per second while maintaining precise paddle movement, which is essential for generating accurate wave models. “Our customers depend on accurate data. Compact Rail Plus ensures that when a wave condition is set, there’s no mechanical loss influencing the results,” he continues.

Load management was another area of improvement. Compact Rail Plus endured these demanding load conditions during durability testing. “We’ve run the system extensively in our wave flume without needing to adjust the bearings. It just keeps performing,” says Matthews.

Interestingly, following review of the tests, HR Wallingford was able to downsize from the initially proposed Compact Rail Plus. “It demonstrated the built-in conservatism of the product. The smaller size proved to be more than adequate, which has allowed optimisation without compromising performance,” notes Prinsloo.

Conclusions

For an organization whose reputation rests on delivering accurate and repeatable hydraulic modelling, improving flexibility, reliability and load management is critical. With Rollon’s solution in place, HR Wallingford can continue to focus fully on their mission: advancing the understanding of how water shapes both natural and built environments.