www.hpmag.co.uk HYDRAULICS & PNEUMATICS June 2026 27 extensive software resources.” The rise of digitalisation is also helping accelerate adoption of electronically controlled hydraulics. Once installed, VSD systems effectively become intelligent data platforms capable of supporting condition monitoring, predictive maintenance, diagnostics and machine performance analysis. “You solve two challenges with one investment,” Bittner explains. “You improve efficiency, but you also gain access to valuable operational data.” At the same time, broader electrification trends are reshaping industrial machine design. According to Bittner, rotary hydraulic functions are increasingly being replaced by electric drives as motor technologies improve in both performance and affordability. Linear motion, however, remains more resistant to full electrification because hydraulic cylinders still offer major advantages in force density, shock resistance, robustness and operation in harsh environments. As a result, many industrial machines are evolving into hybrid architectures combining electric rotary motion with hydraulic linear actuation. Looking ahead, Bittner expects both electromechanical and electrohydraulic actuator technologies to continue advancing rapidly. For Bittner, the direction of travel is fairly clear, even if adoption will not happen at the same pace everywhere. Some industries will move quickly because the financial case already stacks up. Others, particularly more conservative sectors, are likely to take longer as engineers become more comfortable with electronically controlled hydraulic architectures and as existing machine platforms are gradually redesigned. What does seem increasingly difficult to ignore is the broader combination of pressures now shaping industrial equipment design. Energy costs remain a concern, sustainability reporting is becoming more demanding, and machine builders are under pressure to simplify systems while improving performance and diagnostics at the same time. In that environment, variable speed hydraulics are no longer being viewed simply as an efficiency upgrade. Increasingly, they are becoming part of a wider shift towards more intelligent, connected and adaptable machine design. “As the economics continue improving and people become more familiar with the technology, variable speed systems will increasingly become the standard,” says Bittner. For further information please visit: https://www.danfoss.com carbon accounting become increasingly important. “In steel production especially, there is now much greater focus on the energy usage and carbon impact of manufacturing,” says Bittner. “That is creating new incentives to adopt these technologies.” Rethinking hydraulic control Beyond energy savings, one of the most significant developments enabled by modern servo VSD systems is the simplification of hydraulic circuit design itself. Traditional hydraulic systems often rely on multiple proportional valves, pressurereducing valves and flow control valves to regulate machine motion. In contrast, servo-controlled VSD systems directly regulate pressure and flow through the motor and pump. “The prime mover itself becomes the control mechanism,” Bittner explains. This allows many conventional control valves to be reduced or eliminated entirely, simplifying the hydraulic architecture while simultaneously improving efficiency and controllability. “It’s a completely different concept for some customers,” he says. “For more conservative users, the idea that the motor itself is controlling pressure can initially feel unfamiliar. But once they see how well it performs, that hesitation usually disappears.” The precise and highly dynamic pumpspeed control also improves machine responsiveness and accuracy while reducing throttling losses, heat generation and overall system complexity. In many cases, the reduction in heat generation can allow downsizing, or even elimination, of oil coolers. Lower operating temperatures also help extend the lifespan of seals and hydraulic fluid. Noise reduction is another significant benefit. Because the motor and pump operate only at the speed required, machines often run substantially quieter than traditional constant-speed systems, improving operator comfort and reducing workplace noise exposure. Skills, digitalisation and electrification Despite the advantages, integrating VSD technology into hydraulic systems does require a shift in engineering approach. One of the biggest challenges, according to Bittner, is sizing the systems correctly. Traditional hydraulic systems often relied on generous safety margins and oversized components. Variable speed architectures, however, demand a much more detailed understanding of machine duty cycles and operational behaviour. “To size these systems properly, you need to understand the machine cycle in detail,” he says. “You need to know the pressure peaks, the flow peaks, how long they last, how frequently they occur. Many companies simply did not need that level of information before.” This creates both a technical and cultural challenge, particularly for smaller OEMs and engineers whose expertise has historically focused purely on hydraulics rather than electronic controls and drive technologies. To help bridge that gap, Danfoss has integrated p/Q control functionality directly into the drive system itself. The result is that machine builders do not need to develop complex PLC programming to calculate motor behaviour. Instead, the PLC simply requests the required pressure or flow while the drive handles the control logic internally. “The machine builder only asks for the outcome,” says Bittner. “That makes implementation much easier, especially for smaller OEMs that may not have Picture credit: Alba_alioth/Shutterstock.com
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