Fluid Power World August 2026

NEW MATERIAL REPLACES HARD CHROME p.8

PAYING SOMETHING FOR NOTHING?

p .24

THE MAGIC OF VARIABLE-DISPLACEMENT PUMPS p.28

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ELECTRIFICATION

OF MOBILE PAGE 18

MACHINERY

August 2026

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FLUIDLINES Mary C. Gannon • Editor-in-Chief

Join our new Feedback Loop community I’VE HAD AN IDEA BREWING IN MY MIND

all year, and I’ve just kept pushing it off for lack of planning time. But as I read increasingly how it’s becoming more difficult to find qualified fluid power engineers and technicians, I think it’s time we work together as a community to keep this industry strong as we continue to lose some of the pioneers who created these technologies. We are an attractive industry, with a vast variety of careers for technically minded and talented people. As Josh Cosford wrote last month, fluid power is a tech industry and we need to keep it as such.

I’m looking to work with you, readers and hydraulics, pneumatics, and machine technology experts, to offer educational content that will help current and future users or system designers do a better job. Know the best trick to designing your hydraulic power unit or how to optimize your hydraulic hose designs? Have you designed a system or used fluid power in a unique way that others might benefit from learning about?

Share it with each other in our new department called Feedback Loop.

We’re looking to engage with you all to offer insights on timely and important indus-

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try trends, challenges or opportunities. This is how our industry will get better, through an open exchange of ideas.

I invite you to reach out and propose your ideas to me. They can be written articles, such as how-to topics or best-case design scenarios. If writing isn’t your thing, these stories can be shared through an informal recorded chat, where I interview you and share our conversation to Fluid Power World’s readers via video or podcast-style.

These exclusive insights will be shared only with our e-newsletter subscribers, as we work to build a community of trust and camaraderie between those sharing their knowledge and those benefiting from it.

They will be housed on a gated page of our website, where subscribers can log in and find all topics as they come in.

Eventually, the goal is to create an online community of storytellers and experts and bring them together with other users, engaging in a forum around knowledge shared. Then in future, we can host digital roundtables after a topic has been published. These e-newsletter subscribers will be invited to join the live, interactive discussions to swap stories, ask questions and

begin to build our own community.

This subscriber-only content will be found under our Resources tab on fluidpowerworld.com, under “Feedback Loop.” Be sure to keep your newsletter subscription active as we kick these off with industry favorites like Carl Dyke, Dan Fernandes and others.

To maintain editorial integrity, these topics should not focus on selling a product, service, or your company. Nor should they disparage competitors or other organizations.

We encourage you to share positive stories about how you have used hydraulics or pneumatics to create powerful, reliable, and efficient machines. Or perhaps you’ve had a horror story, and you’re hoping to prevent others from making your same mistakes. Our industry needs to open the knowledge pipeline. I encourage you to submit your ideas to me at mgannon@arrowfly.com.

FPW

Mary C. Gannon • Editor-in-Chief mgannon@arrowfly.com linkedin.com/in/marygannonramsak

AUGUST 2026 • FLUID POWER WORLD

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C ONTE NTS | V O L . 1 4 N O . 7

FluidPowerWorld.com

AUGUST 2026

F E AT U R E S 18 MOBILE HYDRAULICS

AUGUST 2026

How has hydraulics' role changed in the electrification of mobile machinery From its massive beginnings to more controllability and efficiency, electrification has changed mobile hydraulics for the better.

24 COMPRESSED AIR EFFICIENCY

Are you paying something for nothing?

Check your compressor control to ensure it matches your plant's demand profile.

28 INDUSTRIAL HYDRAULICS Making magic happen with variabledisplacement pumps Optimizing industrial systems can be done easily with variable-displacement axial piston pumps.

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FLUID POWER WORLD • AUGUST 2026

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D E PA R T M E N T S 3

FluidLines

6

Perspectives

8

Design Notes

12

Component Focus

14

Fundamentals

15

Energy Efficiency

ON THE COVER

Manufacturers began integrating electrical technology into their control systems, and electric solenoid valves became a natural progression from proportional control.

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August 2026 • vol 14 no 7 • www.fluidpowerworld.com

EDITORIAL

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AUGUST 2026 • FLUID POWER WORLD

5

PERSPECTIVES Josh Cosford • Contributing Editor

Technology shmechmology the screw, which helps add torque but requires more rotations. Think of it as a gear ratio, where you must trade force for velocity or vice versa. You can make them fast by increasing the pitch, but you lose the corresponding factor of torque.

Linear actuators that are high-force and high-speed are also "high-sized," and many times larger than a corresponding hydraulic cylinder.

And there is no mechanical free ride with ball screws or rollers, so as rpm rises to blinding speeds, excessive friction leads to heat, lubrication breakdown, and eventual failure. A fast-moving cylinder can generate heat, but it has built-in cooling as fluid circulates. Although low-force electric actuators can move faster than many hydraulic cylinders (those with polymer seals), force output is minor by comparison.

Every new linear actuator startup or neophyte engineer thinks their design is the one to dethrone hydraulic cylinders, until you actually make a comparison … so let's do that. I'm going first to describe a major manufacturer's ELA, and then compare it to the smallest hydraulic cylinder that can (out)perform the same task.

I’ve created a crude illustration (don’t laugh) using one of Higginson's hydraulic cylinders and attached an electric motor under the pretense that there is a ball screw joining them, and then dimensioned it as this off-the-shelf ELA (Figure 1). I’ve also included a 2-in. bore hydraulic cylinder for comparison so you can see how, in fact, there is no possible way an electric linear actuator can approach hydraulics for power density.

FIGURE 1

You can see that this tiny little hydraulic cylinder outputs over three times the force, three times the max velocity, less than half the length, and a fraction of the girth. And you can likely purchase the hydraulic power unit to serve this cylinder at less than the cost of the ELA. Sure, costs will come down over time, but it's too complex ever to undercut the cylinder's price.

So, if you're a champion of linear electric actuators, feel free to send me examples of your golden-child design, and I'll beat it with a catalog-sized hydraulic cylinder. My example was only 3,000 psi. I'll be keeping secret weapons in my back pocket, like the 15,000 psi tie-rod cylinder we made a few years back. Unless your ELA can harness a mini black hole's worth of gravitational force inside its ball screw, I'll sleep easy knowing my challenge will never be met.

FPW

Josh Cosford • Contributing Editor jcosford@higginson.ca linkedin.com/in/joshcosford

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SOME INVENTIONS ARE JUST so damn good that no matter how much AI and data centers you throw at bettering them, modern technology simply cannot replace the simple, legacy equipment we enjoy today. There will be no better method to close your pants than a zipper, nothing superior to an umbrella for a sudden shower, and good luck improving on the bicycle for human-powered transportation.

Correspondingly, electrical linear actuators will never produce the force a hydraulic cylinder does without even trying. Despite the number of people working on electromechanical actuators, they simply can’t even come close.

It all has to do with power density, which is the amount of force and velocity that can be achieved within a given packaging envelope.

An electric motor can only withstand so much magnetic flux before saturation occurs, as you can only pump a limited amount of current into the metal core before all magnetic domains are aligned. Throwing more current at a saturated motor, even those made with cobalt alloys, just results in heat generation. However, even at magnetic saturation, cooling the motor would be nearly impossible since heat scales exponentially with current.

There are linear actuators capable of high force but limited in velocity by the pitch of

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FLUID POWER WORLD • AUGUST 2026

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DESIGN NOTES

By Mary C. Gannon • Editor-in-Chief

MAXTERIAL MAXSHIELD AIMS TO REPLACE TOXIC HARD CHROME OR HEXAVALENT CHROMIUM, IN MANY APPLICATIONS. IT OFFERS THE SAME HARDNESS AND PROTECTION WITHOUT THE TOXICITY.

IT’S NOT OFTEN that you hear the words hydraulics and Erin Brockovich together in the same conversation, but that’s exactly how Mehdi Kargar, PhD, CEO of Maxterial, educated me on how his technology came into being. Hexavalent Chrome, the chemical that was causing cancer and killing people in the Southern California town that inspired the movie, is still used predominantly on hydraulic cylinders to protect rods and other components from wear and corrosion. For decades, hard chrome plating has been the default for cylinder rod protection largely because alternatives have struggled to deliver consistent performance under extreme stress and cyclic loading and at a reasonable cost.

Kargar aims to change that. Things are moving in the right direction with Maxterial’s MaxShield coating technology, as it works to gain

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FLUID POWER WORLD • AUGUST 2026

approval for use in military applications. In early May, the company announced that the Environmental Security Technology Certification Program (ESTCP), the U.S. Department of Defense's environmental technology demonstration and validation program, has selected its MaxShield coating technology for demonstration and validation as a next-generation alternative to hard chrome coating, a heavy-duty wear resistance coating made from hexavalent chromium (Cr⁶⁺).

While the program is focused on defense applications, its significance extends beyond military systems. It will be key particularly within the global hydraulics market — where reliance on hard chrome is being challenged by tightening regulation, rising compliance costs, and the emergence of performanceready alternatives. Kargar noted that his research indicates that about 50 to 60% of

the market using hexavalent chromium is in hydraulics systems.

Hexavalent chromium is classified as a carcinogen and is subject to increasing regulatory scrutiny under OSHA, EPA TSCA, and EU REACH frameworks. The operational burden associated with its use — including safety protocols, emissions controls, waste handling, and long-term liability — has grown materially, transforming what was once a standard material choice into a rising source of cost and risk.

Kargar said there is increased urgency for hydraulic manufacturers and service providers. Regulatory timelines, particularly in Europe, where REACH authorization reviews are tightening through 2027 and beyond, are already influencing procurement decisions, maintenance strategies, and customer expectations.

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MAXTERIAL

Maxterial’s MaxShield aims to replace hard chrome in cylinder use

DESIGN NOTES

Kargar explained that deadlines keep getting pushed to eliminate Chrome 6. They were originally set for 2019, then the deadlines were moved to 2024 and again to 2027, because no viable replacement existed. Currently, the U.S. Army gives providers waivers to allow for its continued use in the short term, but those waivers may no longer be allowed after 2030 if an alternative exists.

MaxShield is field tested and engineered to address this shift directly.

The platform eliminates hexavalent chromium and other hazardous substances while maintaining compatibility with existing industrial processes. Internal and third-party testing indicate strong performance across the metrics most critical to hydraulic applications, including wear resistance, corrosion resistance, adhesion strength, and lifecycle durability. Hydraulic parts coated in MaxShield have already been installed in plants.

"From a mechanical standpoint, hydraulic components represent one of the most demanding environments for surface performance, particularly under cyclic loading and high contact stress," said Carlo Mapelli, Researcher at the Department of Mechanics at Politecnico di Milano. "What is becoming increasingly clear is that alternative coating systems can now be engineered to match — and in some cases exceed — the performance of hard chrome in these conditions. That fundamentally changes the risk profile of transition."

Maxterial was born through an original work at Virginia Tech. At the time, Peter Thiel’s Breakout Labs was working on funds to support breakthrough technologies and reached out to suggest Kargar and his team start a company. Not long after, BASF also encouraged the founders to actively pursue commercialization. Then repeated requests and questions came for Kargar’s team to look into Hastelloy chrome replacement. “In 2018 for the first time, we made an alloy of nickel and molybdenum. And then it took eight years to perfect it,” Kargar said.

The shift to MaxShield is already being validated in real-world oper-

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FLUID POWER WORLD • AUGUST 2026

ating environments, where performance, uptime, and regulatory exposure converge. In particular, he mentioned that hydraulic parts coated in MaxShield have been used in steel mills in both US and Europe for more than a year and, in both cases, MaxShield has shown an excellent performance.

Dayne Thomas, Vice President of Engineering and General Manager of Ohio-based Dover Hydraulics, a Sunsource Company, emphasized the impact on operation costs where every second costs money. "Hard chrome is becoming more difficult to source, with reduced availability, rising costs, and long lead times. In maintenance, time is everything — we're managing downtime in steel mills and large industrial plants where every hour has a real cost. We also handle parts with a wide range of sizes and complex geometries, where chrome can be restrictive,” Thomas said. “MaxShield's lower dependency on geometry is a major advantage, allowing for faster turnaround and more flexible, practical deployment in the field."

That shift is also being reflected in market behavior, particularly in Europe, where regulatory pressure is accelerating adoption timelines and forcing earlier transition decisions. Marco Sighinolfi, Chief Technology Officer, Idraulica Sighinolfi, underscored the importance of aligning compliance with enhanced performance. "Beyond the well-known regulatory and health concerns associated with chrome, there are many hydraulic applications where it simply falls short in performance or compatibility,” Sighinolfi said. “From our testing, MaxShield delivers superior performance and unique capabilities that could position it as a universal solution across the hydraulic industry.

This shift has the potential to dramatically simplify the supply chain — reducing complexity in sourcing, inventory, and service, while lowering overall costs."

"ESTCP's selection reflects the importance of advancing technologies that can address both performance requirements and environmental

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MAXTERIAL (2)

A MAXTERIAL MAXSHIELD SAMPLE SHOWS ONE OF THE BIGGEST USERS OF HARD CHROME — HYDRAULIC CYLINDERS.

FPW

Maxterial maxterial.com

A CONCEPT SHOWING MAXTERIAL’S MAXSHIELD COATING.

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FLUIDYNE

challenges within defense systems," said Kargar. "MaxShield is designed to support operational readiness while enabling a broader industrial transition — especially in hydraulics — where the need for safer, more efficient, and more sustainable solutions is already reshaping the market. We already have had early commercial traction in pneumatic systems, in particular shock absorbers, on commercial vehicles.

"This project aligns with ESTCP's mission to identify and demonstrate innovative environmental technologies that address critical DoD requirements," said Dr. John La Scala, Program Manager for Weapons Systems and Platforms for ESTCP. The ESTCP demonstration project began in April 2026, with evaluations spanning multiple service branches and sustainment environments. As validation progresses, its implications are expected to extend across industrial sectors facing similar regulatory and performance pressures, accelerating the transition away from hard chrome in hydraulics and beyond.

While the company expects this DoD review to be completed in late 2026, it is also in the process of finalizing additional testing across the greater armed services and defense communities.

AUGUST 2026 • FLUID POWER WORLD

11

COMPONENT FOCUS Josh Cosford • Contributing Editor

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WHEN A PNEUMATIC SYSTEM suffers a catastrophic failure, such as a blown seal, a ruptured airline, or a seized cylinder, the maintenance team must respond instantly to treat it. These unexpected ailments reduce productivity, increase costs, and work your millwrights ragged.

Many pneumatic systems experience chronic unwellness, much as we humans do with cardiovascular disease; so too do pneumatic systems suffer from "pneumatic cholesterol."

Pneumatic cholesterol is the gummy, sometimes abrasive varnish that forms when raw, compressed air is permitted to contaminate the veins and organs of your air circuit. When you combine atmospheric moisture, compact it into a smaller space, and add microscopic particles too fine for the inlet filter and ingested by the air compressor, you create dangerous LDL-level pneumatic cholesterol. Now add the heat of compression along with a sprinkle of compressor oil, and you’re looking at oxidized ApoB level lipoproteins ready to infect your entire pneumatic system.

Unlike the myocardial infarction, which is a catastrophic pneumatic failure, such as a burned-out valve coil or blown manifold O-ring, pneumatic cholesterol manifests slowly yet malignantly. It coats high-precision spools, emulsifies with water and assembly lube, and turns to varnish when exposed to prolonged heat. Valves stick, cylinders chatter, and repeatability goes out the window.

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FRLs for compressed air prep and care

at nearly every leg of the system.

The filter traps the raw materials required to formulate pneumatic cholesterol, such as water, particles, and oils, before they can combine into a nasty paste ready to destroy the inside of all you love. Pneumatic filters use a cyclonic effect to remove fluids, and the sintered bronze filters trap what’s left with a single-digit micron efficiency. Filters will collect so much water, in fact, that manufacturers offer them with automatic drains.

The regulator keeps ("blood") pressure in check, providing enough to operate cylinders and motors without dizzy spells while preventing excessive, damaging pressure that would tax the compressor. Remember that up to 90% of the energy used in pneumatic systems is wasted as heat from compressing air, so get that "resting heart rate" (pressure) down by reducing your compressor's unloading pressure.

You will experience a gradual loss of efficiency, and, just as with your own body, you may not notice until symptoms arise (hopefully mild in both cases!). You may experience reduced cycle times, production bottlenecks, or a single-point failure that can lead to cascading failures in sophisticated factory automation applications. When you practice reactive maintenance rather than preventive maintenance, you essentially subscribe to “sick care” rather than healthcare.

We now know that lifting heavy weights, eating whole, unprocessed foods, and engaging in bursts of high-intensity exercise will prevent 99% of today's cardiovascular and metabolic diseases, and so too can you prevent such chronic conditions in your pneumatic system.

Preventing the slow, operational decay of your machine from the inside out doesn't have to be the sole responsibility of your FRL (Filter, Regulator, Lubricator). Still, it's certainly one of the most important and effective interventions for the task. There's a reason you see FRLs strategically positioned throughout your facility and

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Of course, any solid health regimen can't do without a supplementation protocol. Vitamin D, magnesium, creatine, and fish oil are staples to any health journey, and so too is the lubrication you add back in for your precious and sensitive valves, regulators, and actuators.

A lubricator will deliver a micro-mist of fresh, clean oil to neutralize friction while protecting moving components with minimal friction and maximum cooling, helping wash away varnish buildup before it clogs pneumatic arteries.

Just like diet and exercise are mandatory to good bodily health, FRLs are the single most effective component to install throughout your facility to show your pneumatic machines how much you love them and care about their cardiovascular health.

FPW

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AUGUST 2026 • FLUID POWER WORLD

13

FUNDAMENTALS

By Ken Korane • Contributing Editor

HYDRAULIC HOSE FITTINGS are essential in is also an advantage, especially in stationary and mobile machines. They ensure remote or rural areas where new safe and reliable operations and prevent equip- components or crimpers may not ment shutdowns, catastrophic failures and dan- be readily available. ger to nearby personnel.

But are field-attachable fittings And in the hydraulics world, there are gen- truly reusable? erally two types of hose fittings — permanent Many experts agree that, in a and reusable or field-attachable. Permanent perfect world, it’s always preferred crimp fittings mechanically interlock to hose to opt for new fittings when a user by means of a crimping or swaging machine reassembles the connections. But, and form a durable, leak-proof connection. A thanks to improvements over the crimp fitting cannot be removed and reinstalled. years in terms of better materials, designs and PARKER HANNIFIN’S 82 SERIES ONE-PIECE, PUSH-ON HYDRAULIC FITTINGS ALLOW Reusable fittings, as the name implies, are manufacturing processes, hydraulic fittings in FIELD-ATTACHABLE USERS TO CONFIGURE HOSE ASSEMBLIES QUICKLY AND designed to be used multiple times. These good working order can sometimes be reused. EASILY IN THE FIELD WITHOUT SPECIAL TOOLS. hydraulic fittings can be disassembled and reasSeveral factors come into play when considsembled so that modifications or repairs can be ering whether hydraulic fittings can be reused. seal. Excessive torque can permanently distort made to the hydraulic system without replac- The most crucial is the condition of the fitting. the interfaces and lead to an insufficient seal. ing the entire hose assembly.

A fitting may appear in good condition, but it Again, best practice is always to replace a fitGiven that these fittings may be consid- must be inspected before reuse. ting with new parts. But if the fitting is found ered for reuse, they can make for an economVisually check for any signs of concern: to be in good condition, and the user opts for ical choice in applications where field repairs • Wear or damage on the fitting, such as reuse, here are a few additional tips. First, plan are necessary or frequent changes are anticicracks or deformations. to reassemble the assembly with new hose — pated. And the relatively simple design facili- • Nicks or scratches to any sealing surface. not the existing worn or damaged hose. Contates quick disassembly and reinstallation, sav- • Corrosion, rust, or material deterioration firm that the hose and fitting are compatible ing both time and labor costs. that can weaken the metal and compromise in terms of material, size, and pressure ratings.

One major drawback is their general unsuitthe fitting's integrity.

Before reusing the fittings, they must ability for high-pressure use. The absence of a • Physical abuse such as dents or any distor- be thoroughly cleaned, as any dirt or debris mechanical lock typical in crimp fittings reduces tion to the shape of the fitting. could potentially enter the hydraulic system their overall pressure tolerance. Reusable fit- • Fitting nose collapse. and cause damage. Ensure you are following tings tend to be limited to low-to-medium presIf there are any signs of damage, the fitting the proper procedures for reassembly. Never sure applications up to around 3,000 psi. should be replaced to ensure the safety and mix fittings from different manufacturers or use Therefore, these fittings are generally pre- reliability of the hydraulic system. In addition, “similar looking” parts, and follow the guideferred when adaptability and flexibility are it’s best to replace O-rings or seals regardless lines provided by the equipment manufacturer. more critical than high-pressure performance. of how they may look.

After reassembly, look for any signs of These include prototyping hydraulic systems And many industry representatives do not improper installation, such as misalignment that are still being tested and require frequent recommend reassembling tapered thread or visible gaps. And finally, test the new conmodifications. In high-speed industrial produc- pipe fittings and JIC 37° flare fittings. Pipe fit- nection to ensure the seal is tight. If there are tion and assembly operations, downtime can ting connections rely on deformation of the any leaks, replace the assembly immediately. be costly. Where pressure requirements are sealing threads to obtain a seal, and they can In the end, be critical and always err on the moderate, field-attachable fittings help to make wear out or deform with repeated assembly side of caution. If you have any doubts — if you quick or emergency repairs right at a machine. and disassembly. question the viability of the fitting in any way — In less critical mobile systems like agriculJIC 37° flare fittings use a cone and flare con- it is always best to replace the fitting to avoid tural sprayers or other low-pressure hydrau- nection to seal. The connection causes a slight potential risks. lic machinery, the fitting’s on-site repair ability deformation of the metal surfaces to obtain a FPW

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FLUID POWER WORLD • AUGUST 2026

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PARKER HANNIFIN

Are field-attachable fittings truly reusable?

ENERGY EFFICIENCY Ron Marshall • Contributing Editor

Is your air dryer quietly wasting energy?

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Then Mark started thinking about another part of the plant, an area with more sensitive equipment that needed extra-dry air. Sure enough, that section was served by a desiccant dryer. Back at the seminar, he had learned that desiccant dryers are used when you need a much lower dew point, often around-40° F. These dryers use towers filled with moisture-absorbing desiccant beads instead of refrigeration.

They’re effective, but they can also be energy hogs if you’re not careful.

Mark remembered learning about the three main types. Heatless dryers are simple and reliable, but they can use up to 15-20% of your compressed air just to regenerate the desiccant. In other words, a noticeable chunk of the air you’re paying to produce never makes it to production.

Heated dryers reduce that purge air loss by using electric heaters. Heat-of-

compression dryers are appropriate if you have oil-free compressors, and can be even more efficient by reusing the heat already produced by the compressor.

Suddenly, Mark wasn’t just looking at dryers. He was looking at opportunities.

He also realized something else the seminar had emphasized: even a good dryer can waste energy if it isn’t maintained properly. Dirty filters, failed drains, pressure drop, or incorrect control settings can quietly chip away at system efficiency.

By the end of his inspection, Mark had learned an important lesson: You don’t need the driest air possible everywhere in your plant, you just need the right dryer for the job. And sometimes, the biggest savings don’t come from buying a new compressor.

Sometimes, they come from finally paying attention to the equipment that’s been sitting beside it all along.

FPW

RON MARSHALL

MARK HAD ALWAYS CONSIDERED

himself a capable plant manager. He knew his way around the facility, understood the production demands, and trusted his maintenance team to keep things running.

As far as he was concerned, the compressed air system was doing its job. The air was dry, production wasn’t complaining, and the compressors were humming along like they always did.

Then Mark attended a Compressed Air Challenge Fundamentals of Compressed Air Systems seminar. That’s when he realized he might have been overlooking one of the most important parts of the system: the air dryers.

During the seminar, the instructors explained how dryers can have a surprisingly large impact on both energy efficiency and system reliability. Mark found himself thinking, Wait a minute … what kind of dryers do we actually have in our plant? And are they the most efficient choice? When he got back to work, curiosity got the better of him.

He headed straight for the compressor room.

The first thing he found was a refrigerated dryer, which is the most common type in industry. That made sense. Refrigerated dryers work a lot like your kitchen fridge, cooling compressed air to around 35° F, so moisture condenses and can be removed before it travels into the plant.

But then Mark remembered something from the seminar: Not all refrigerated dryers are created equal. He checked the unit and realized his plant had a non-cycling dryer.

That means it runs at full power all the time, whether the plant is using a lot of air or hardly any at all. That was a bit of a wake-up call.

His plant’s air demand dropped significantly during evenings and weekends, yet the dryer kept working just as hard. If the plant had a cycling refrigerated dryer, it could reduce energy use during low-demand periods by backing off when less drying was needed.

TO REDUCE COMPRESSED AIR ENERGY CONSUMPTION YOU SHOULD LEARN ABOUT TYPES OF AIR DRYERS AND HOW THEY AFFECT OVERALL SYSTEM EFFICIENCY. COMPRESSED AIR CHALLENGE SEMINARS CAN HELP.

AUGUST 2026 • FLUID POWER WORLD

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Sponsored by HYDAC North America

Electrification Is Reshaping Fluid Power— Not Replacing It

By Ed Polzin, Product Manager – E-Mobility Technologies, HYDAC North America

F

or years, discussions surrounding equipment electrification often suggested that hydraulic systems would eventually be replaced by electric alternatives. However, the reality unfolding across off-road equipment, mobile machinery and industrial vehicles is far more nuanced.

Rather than eliminating fluid power, electrification is driving the development of new electrohydraulic architectures that combine the force density and controllability of hydraulics with the efficiency and flexibility of electric drives. As OEMs face growing pressure to reduce operating costs, improve machine productivity and meet evolving emissions requirements, many are discovering that the most practical path forward is not full battery-electric equipment, but strategically electrifying hydraulic functions where they deliver the greatest value.

Total Cost of Ownership Is Driving Adoption While sustainability goals and emissions regulations often dominate industry headlines, conversations with OEMs and end users reveal a different primary driver: total cost of ownership (TCO).

For equipment owners, reducing fuel consumption, lowering maintenance costs and maximizing uptime have become critical business objectives.

Although electrified systems may increase upfront machine costs, those investments are increasingly being evaluated over the entire lifecycle of the equipment rather than at the point of purchase.

When properly applied, electrification can reduce engine run time, decrease fuel consumption, and minimize wear on key components.

Over time, these benefits can offset initial capital expenditures while delivering measurable improvements in operating efficiency.

As a result, electrification is increasingly being viewed as a business decision rather than solely an environmental initiative.

Electrification Doesn't Mean Eliminating Hydraulics One of the most common misconceptions surrounding electrification is that it requires a complete transition away from hydraulic systems. In reality, hydraulics continue to offer unmatched power density and force generation in many mobile equipment applications.

Instead, OEMs are increasingly examining opportunities to decouple hydraulic functions from internal combustion engines.

Traditionally, many machines require the engine to remain running simply to power hydraulic work functions. This creates fuel inefficiencies, unnecessary maintenance, and operational challenges, particularly in environments where antiidling regulations are becoming more common.

By electrically driving hydraulic pumps and other work functions, machines can perform required tasks without continuously operating 16

FLUID POWER WORLD • AUGUST 2026

the engine. The result is a more efficient architecture that preserves the performance advantages of hydraulics while reducing fuel consumption and engine wear.

In many applications, electrification is enhancing fluid power systems rather than replacing them.

Hybrid Systems Offer a Practical Middle Ground For many OEMs, hybridization is emerging as the most practical path toward broader electrification.

Hybrid systems allow manufacturers to selectively electrify functions that provide the greatest operational benefit while avoiding the infrastructure, range, and charging challenges that can accompany full battery-electric designs.

Consider a service vehicle operating in an urban environment. Traditionally, the vehicle's engine would need to idle while hydraulic systems perform their work. By powering those hydraulic functions through batteries and electric motors, operators can shut down the engine while continuing to perform required tasks.

This approach not only reduces fuel consumption but also decreases maintenance requirements, lowers noise levels, and helps organizations comply with anti-idling regulations.

More importantly, it demonstrates how electrification can be applied strategically to solve specific operational challenges rather than serving as an all-or-nothing proposition.

Efficiency Gains Start with System Architecture As equipment manufacturers evaluate electrification opportunities, many are also reexamining the efficiency of existing hydraulic architectures.

Historically, hydraulic systems have often been designed around fixed engine-driven components that operate regardless of actual demand. Electrification creates opportunities to rethink these architectures by allowing pumps, fans and auxiliary functions to operate only when needed.

This demand-based operation can significantly improve overall system efficiency while simplifying packaging and reducing parasitic losses.

Thermal management is also becoming increasingly important as electrified systems are introduced. Batteries, power electronics, and electric motors all operate most efficiently within specific temperature ranges. Effective thermal management strategies help maintain performance, improve reliability, and extend component life.

As a result, system-level optimization is becoming just as important as component-level innovation.

The Future of Fluid Power Is Increasingly Electrohydraulic The evolution occurring in mobile machinery today mirrors changes that transformed the automotive industry over the past several decades.

Many automotive subsystems that were once mechanically driven directly from the engine have gradually transitioned to electrically driven architecture. This shift improved efficiency, reduced maintenance requirements, and provided greater flexibility in vehicle design.

A similar transformation is now underway in offroad equipment.

As battery technology, charging infrastructure and power electronics continue to advance; full battery-electric machines will become increasingly viable across more applications. However, the near-term future for many equipment manufacturers will likely involve hybrid and electrohydraulic solutions that deliver immediate operational benefits while leveraging existing machine architectures.

For fluid power professionals, this presents a significant opportunity. The future is not a choice between hydraulics and electrification. Instead, it is the convergence of both technologies into smarter, more efficient, and more productive machine systems.

Ed Polzin is Product Manager – E-Mobility Technologies for HYDAC North America. He specializes in electrification strategies for off-highway mobile equipment, helping OEMs integrate electric drive systems with advanced hydraulic technologies to improve efficiency, productivity and machine performance.

Visit hydac.com/en-us for more information www.fluidpowerworld.com

Beyond Components.

Engineering system performance through our Integrated Systems Approach.

Fluid Power Engineering.

Controls & Electronics Engineering.

Application & System Engineering.

One integrated approach. One performance-driven outcome.

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MOBILE HYDRAULICS

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FLUID POWER WORLD • AUGUST 2026

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MOBILE HYDRAULICS

HOW HAS HYDRAULICS’ ROLE CHANGED IN THE ELECTRIFICATION OF MOBILE MACHINERY?

From its massive beginnings to more controllability and efficiency, electrification has changed mobile hydraulics for the better.

By Josh Cosford, Contributing Editor

FIGURE 1. EARLY ELECTRIFICATION OF HYDRAULICS STARTED WITH GIANT, STATIONARY STEAM ENGINES ROTATING FLYWHEELS, WHICH IN TURN DROVE A DOWNSTREAM ARRAY OF SHAFTS, PULLEYS, AND LEATHER BELTS TO POWER LATHES, DRILLS, MILLS, OR EVEN HYDRAULIC PUMPS.

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MOBILE HYDRAULICS

FIGURE 2. INSTALLING SOLENOID VALVES ON MOBILE MACHINERY WAS A NATURAL PROGRESSION FROM PROPORTIONAL CONTROL.

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the investment cost and the real estate required for steam engines and their accoutrements.

Those individual electric motors were great for rotating hydraulic pumps, of course. When power was provided at the place of operation rather than at the place of creation, the functional opportunities expanded exponentially, with creative new ways to solve problems. Hydraulic pumps with rudimentary power units, often with just a pump and motor, powered presses, shears, machine tool and various other mechanical production technologies.

Hydraulic machines were previously nothing like what you know today, and any technician who’s had the opportunity to work on a centenarian press can back me up. Individual spool valves, such as monoblock lever valves or industrial stack

valves, had not yet been invented. Their control methods were entirely bespoke and products of the manufacturer's engineering team. The reservoir, fluid passages, and valves were part and parcel of the machine itself, contained within the enormous casting rather than separately plumbed, bought-out components.

Eventually, of course, manufacturers began integrating electrical technology into their control systems, and electric solenoid valves were combined with poppet and spool valves to create bang-bang valves that could be operated remotely via switchgear rather than by machine operators using levers.

CONTROLLING WHAT MOVES IN THE AIR Of course, this article is about mobile machinery, so it’s clear our discussion must

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HE ELECTRIFICATION OF HYDRAULICS has come a long way since the first AC induction motors powering hydraulic pumps replaced centralized power distribution systems.

Such immense systems, Figure 1, employed giant, stationary steam engines rotating flywheels, which in turn drove a downstream array of shafts, pulleys, and leather belts to power lathes, drills, mills, or even hydraulic pumps.

A line shaft factory was an insane, noisy place where injuries were as frequent as repairs. They were ingenious at the time, as there was no other method to create a room full of industrial or commercial machinery, but a decentralized power system would clearly be a welcome change.

If you could run said lathe, drill, or mill with electric motors, you would save on

MOBILE HYDRAULICS

THE MOVE TO MORE DIGITAL HYDRAULICS MEANS THAT MOBILE HYDRAULIC ROBOTS, LIKE GRAVION’S PURPOSE-BUILT, ULTRA-LOW PROFILE UTILITY ROBOT, ARE GROWING IN USE.

GRAVION

switch gears. In fact, if you consider aviation to be mobile technology, missiles and airplanes were one of the first industries to adopt electrohydraulic technology. Sometimes technology advances out of necessity, and the electronic control of hydraulics was no different. You might be surprised to learn that Bill Moog invented servo valve technology out of necessity during the Cold War. As America’s supersonic missile technology pushed the limits of speed, the forces applied to fin and canard surfaces increase with the square of velocity. Imagine the difficulty of aiming something that requires millisecond precision at over Mach 3. In 1951, Moog was contracted by the U.S. Navy to develop hydraulic control technology for advanced surface-to-air systems.

It didn't end there — Moog valves played a role in American air dominance, being

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employed on everything from B-2 bombers to Saturn V rockets, and eventually, every advanced fighter jet. Fly-by-wire systems use analog control methods with feedback, comparing the desired position with the actual position to make fine adjustments quickly and accurately. Using current rather than voltage control signals, ±8 to ± 50 and eventually 4-20mA, this method was important to prevent voltage drops over long distances using other methods.

MOVING TO THE GROUND I know what you’re thinking: aviation isn't exactly "mobile" hydraulic technology, at least not as we describe it today. But c’mon, what’s more mobile than an intercontinental ballistic missile? Servo valve technology wasn’t ignored by the Army, of course, and it was adopted for the M1 Abrams tank.

So-called "shoot on the move" technology allowed the Americans to keep the aim of their turret and heavy gun fixed on their target despite the bouncing and swaying of a massive machine moving at speed. Previous systems required the tank to be stationary to aim, so imagine, for the first time, facing such a moving target that shot back.

And with that, servo-controlled, land-based mobile hydraulic machinery was born.

Of course, commercial mobile equipment wasn’t quick to adopt servo valves for every actuator. It turns out excavators and tractors weren't practical with militarylevel budget and cleanliness requirements.

Hydraulic pilot controls, such as joysticks and levers, work perfectly well, despite the expense of plumbing, which also adds complexity and mass.

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visual execution of functions, as opposed to simply pushing buttons or operating switches.

And with the capacity to interface with the Human Machine Interface (HMI) in new ways, infrequent functions could be buried in menus, which, in a contradictory way, both reduce and increase machine complexity. Manufacturers could hide a function within a menu rather than install rarely used switchgear, avoiding the appearance of an airliner cockpit. Conversely, machine functions could be embedded in software, allowing engineers to increase functional complexity without additional hardware.

SLOW ADOPTION OF ELECTRONIC CONTROL But early digital electronics were not known for their all-weather ruggedness, and mobile hydraulic machinery was slow to adopt what was common in the factory. A farm tractor was just not a good place for an electron-tube television, with poorly conditioned electrical power, high vibration, and electromagnetic interference.

It wasn’t until Liquid Crystal Displays (LCD’s) or Vacuum Fluorescent Displays (VFDs) were invented that mobile hydraulics

were able to offer digital displays, and even then, were more likely to replace simple mechanical gauges with information such as speed, RPM, pressure, and temperature, and were hard-wired with no menus or configurability.

Fast forward to the mid-90s, and the electronic control of mobile machinery took off. It was Bosch's invention of Controller Area Networks that allowed multiple computers to communicate, and then the decreasing costs of microchips that enabled computers and their software systems to take off in mobile machinery.

GROWING USE IN THE NEW MILLENNIUM Throughout the 2000s, big players such as Danfoss, Rexroth, and HydraForce offered rugged, programmable controllers that enabled small OEMs to customize the performance and functionality of their offerings. Previously, only the big guys, like John Deere or CASE, could take advantage of such advanced technology. Now, feed mixers, stone slingers, woodchippers, and the small OEMs building them can employ CAN-ready ECUs, various transducers, LED displays,

THE NEW MILLENNIUM SAW MORE USE OF PROGRAMMABLE CONTROL, LIKE THIS HY-TTC 500 CONTROLLER FROM TTCONTROL, WHICH WAS DESIGNED FOR MOBILE MACHINERY.

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HYDAC

CHANGING THE MOBILE VALVE GAME It wasn't until we Gen X were toddlers that manufacturers such as Rexroth and Danfoss began introducing proportional solenoids for the mobile market, and since then have been competing in a 50-yearold game of heads-up electro-proportional poker. Instead of the micron-level precision of servo-valve internals, which require the world's finest filtration and continuous maintenance, proportional valves offered variable flow via metered spool valves and PWM control, marrying directional and metering valves.

PWM (Pulse Width Modulation) is a method for digitally mimicking a variable current by rapidly switching between full and zero power. Using an analog input, such as a joystick outputting 4-20mA signals to a valve controller, mobile machinery was able to mimic the effect of a servo valve, albeit with less precision, but also less cost and maintenance in a more robust package.

For decades, and still today, these sectional proportional valve systems have controlled everything from excavators to stone slingers and everything in between. A cab with only electrical wires routed to pedals and joysticks eliminated the cost and complexity of running dozens of pilot lines between each pilot controller and the pumps and valves at various locations throughout the machine.

Electrification wasn’t limited to proportional control, and manufacturers liked the idea of operating simple functions with switchgear and bang-bang valves, so installing solenoid valves on mobile machinery was a natural progression (Figure 2).

For simple on/off, up/down, and side-to-side functions like downriggers, 3-pointhitch functions, and conveyors, the solenoid valve was the best choice for cab-operated hydraulic functions, especially aftermarket attachments.

Despite the popularity of computer technology, including displays, it gained popularity within the industrial space first, helping operators and technicians in myriad ways. The first and most obvious is the

and all the weatherproof connection technology needed to pull it together.

Throughout the 2000s and until the pandemic, electrification exploded. Not only did the hardware become economical, but trade colleges, equipment manufacturers, and associations such as the International Fluid Power Society also emphasized the importance of electrical integration, so the number of fluid power professionals educated in digital electronics grew rapidly as well. Mechatronics diplomas, electronic controls specialist, and various micro-credential certifications could be achieved by students and mature professionals alike. In fact, if you're a hydraulic professional at any age, you're likely well-trained in some form of electronic control.

BECOMING DIGITAL Industry 4.0 didn't overlook mobile hydraulics and has only accelerated the

use of digital electronics in machinery.

Telematics and advanced data transmission technology keep machines connected to the World Wide Web, providing data and feedback on machine status and performance for the benefit of both bean counters chasing profitability and mechanics chasing reliability.

No matter where you stand with online, offshore retailers such as Temu, AliExpress, and let’s be real, Amazon, you can’t deny the saturation of inexpensive digital electronics in mobile hydraulics. Sure, it's caused the displacement of some hydraulics within our industry, as electric motors are as inexpensive and powerful as ever. But Bluetooth controllers, microcontrollers, commodity-priced sensors, digital screens, and everything you could need to build a machine with as little hydraulic control as possible, it’s hard to hide from the paradigm shift.

Today, pumps, motors, and cylinders are means to an end, at the whim of digital control, and part of an ecosystem expanding at light speed, so fast that most of us don't know what is next. Mobile hydraulic robots are flooding the industry, artificial intelligence is coding on our behalf, and online connectedness tells us everything about our machine or fleet, all at once.

It’s hard to deny the importance of electrification in mobile machinery, but I’m here to reassure you that hydraulics will always be a critical piece of the puzzle. Electrical linear actuators can never achieve the performance of hydraulic cylinders, but I’ll concede these next twenty years are going to be a wild ride.

FPW

SAVE THE DATE! SICFP ’27 – The 20th Scandinavian International Conference on Fluid Power June 1-3, 2027 A Key Meeting Place for Fluid Power and Off-Road Mobile Machinery

Hosted by the IHA - Innovative Hydraulics and Automation at Tampere University/ Finland, the conference covers relevant topics of robotics, automation and digitalization through: • More than 50 scientific paper and research presentations • Industrial exhibition • Networking between international academia and industry

Sponsors and exhibitors are welcome

Learn more at events.tuni.fi/sicfp2027

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AUGUST 2026 • FLUID POWER WORLD

23

COMPRESSED AIR EFFICIENCY

GREAT CARE IN MAINTAINING YOUR COMPRESSOR AND ITS CONTROLS IS CRITICAL TO RELIABLE AND EFFICIENT COMPRESSED AIR USE.

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COMPRESSED AIR EFFICIENCY

ARE YOU PAYING

SOMETHING

FOR NOTHING?

Check your air compressor control to ensure it matches your plant’s demand profile.

By Ron Marshall, Contributing Editor

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N MANY INDUSTRIAL PLANTS, the real cost of compressed air isn’t just the air being used on the production floor, it’s the energy consumed when the compressor is running — but not producing useful air. Choosing the wrong operating mode for your compressor can be surprisingly expensive. It’s a bit like sitting at a red light with your car engine revving high.

Fuel is being burned, but you’re not going anywhere.

Energy specialists working with compressed air systems regularly see facilities lose thousands of dollars every year simply because the compressor control strategy doesn’t match the plant’s demand profile. Understanding the different operating modes is one of the simplest ways to uncover hidden energy waste.

Let’s take a closer look at the most common compressor control strategies and how they affect efficiency.

COMPRESSOR CONTROL STRATEGIES Start/stop control — Start/stop control is the simplest method. The compressor starts when system pressure drops below a set point and shuts off completely when the pressure reaches the upper limit.

This approach is very efficient because the motor turns off entirely when air is not needed. However, it’s typically limited to smaller reciprocating compressors with relatively infrequent demand cycles. Large rotary screw compressors generally cannot use this method because repeated motor starts generate heat and cause excessive wear on the equipment.

Load/unload (online/offline) — Load/ unload control is extremely common in rotary screw compressors. In this mode, the motor continues to run even after system pressure reaches the upper set point, but the compressor stops producing air.

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COMPRESSED AIR EFFICIENCY

While this avoids repeated motor starts, it introduces a hidden cost. An unloaded compressor can still consume 25–30% of its full-load power while producing zero air. If the system does not have enough receiver tank capacity to stabilize pressure, the compressor can short cycle between load and unload repeatedly. This wastes energy and increases mechanical wear.

Modulation — Modulation (inlet throttling) control adjusts output by restricting the air entering the compressor. The inlet valve partially closes to reduce capacity while the compressor continues to run.

Although this method keeps system pressure very stable, it is one of the least efficient control strategies. A compressor operating at only 50% capacity under modulation can still consume 80% or more of its full-load power. In effect, the machine is working nearly as hard but producing much less air.

Variable displacement control — Some compressors use variable displacement technology to adjust capacity by altering the internal compression process. This allows the compressor to reduce output without fully unloading.

While more efficient than traditional modulation, variable displacement systems still experience efficiency losses at lower loads. They are often used to maintain stable pressure while avoiding frequent load/unload cycling.

Variable speed drive (VSD) — Variable speed drive technology is widely considered the most efficient control method for systems with fluctuating demand. Instead of running at a fixed speed, the motor adjusts its speed to match the plant’s air demand in real time.

This allows the compressor to produce exactly the amount of air required without wasting energy in unloaded operation. In many applications, properly applied VSD compressors can deliver energy savings of 35% or more.

The pressure factor — Beyond control modes, system pressure also plays a major role in energy consumption. The rule of thumb promoted by the Compressed Air Challenge is simple: for every 2-psi reduction in system pressure, energy consump-

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FLUID POWER WORLD • AUGUST 2026

tion drops by roughly 1%.

Reducing pressure also lowers artificial demand and leak losses throughout the plant by about 1% for every 1 psi reduced if the demand is unregulated.

RUNNING MULTIPLE COMPRESSORS When controlling screw compressors, the goal is to try to keep all the running compressors fully loaded except one. And the one running partly loaded (called trim) is

selected as the one having best part load efficiency characteristics.

When there are only two or three compressors in a group, it is quite easy to set them up manually with cascaded pressure bands. However, as the number of compressors in the group increases, it gets more difficult to meet the stated goal.

On the upper end of the operating pressure band is the maximum rating of the compressors; on the lower end is the lowest allowable system pressure. As we try to

Obsolete compressor controls create false economy

THE CONTROLS ON THIS COMPRESSOR ARE OBSOLETE AND POORLY ADJUSTED, RESULTING IN EXTREMELY INEFFICIENT Recently, a compressed air OPERATION. THIS UNIT RECENTLY UNDERWENT END auditor AN ranEXPENSIVE across aAIR newly REBUILD, WHICH WAS FALSE ECONOMY — A compressor at a wood NEWrebuilt MORE MODERN COMPRESSOR WOULD HAVE QUICKLY PAID BACK ITSThe COST. products company. unit

was cleaned up nicely and had a shiny new air end due to a rebuild — but because the unit had obsolete controls, this compressor continued to run very inefficiently. Saving money by rebuilding this compressor was false economy.

The compressor in question was sent for repair because it couldn’t hold pressure. Lack of capacity was the suspected issue, so air end failure was suspected. However, when the unit returned, after the expensive repair, the pressure problems continued. Closer inspection by the air auditor found the unit had both modulation and variable displacement controls, both adjusted by turning a bolt on the bottom of the subtractive pilots placed on the right side of the units (red boxes).

These controls were not coordinated properly, resulting in the air end being permanently set to half capacity and below. This caused low pressure when the compressed air demand exceeded the available capacity, which was less than half the rated capacity. Very often, units such as these are incorrectly adjusted because many well-meaning but poorly trained technicians have wrenches.

Newer, more modern controls, have electronically adjusted settings. The newer compressors are also much more efficient than the old units — manufacturers have made great advances in compressor technology.

Lesson: When repairing a failed compressor, owners and operators should consider that a rebuild may not be in their best interest if they want to save operating costs in the long run.

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COMPRESSED AIR EFFICIENCY

THE PRIMARY WAYS TO CONTROL COMPRESSED AIR PRODUCTION COSTS ARE TO PRODUCE THE AIR MORE EFFICIENTLY BY ELIMINATING UNLOADED RUN TIME AND CHOOSING THE MOST EFFICIENT COMPRESSOR OPERATING MODES.

cram more and more compressor set points in this narrow window, the settings get closer and closer, resulting in some undesirable overlap.

To solve this problem, compressor controllers are used to logically select the next compressor to load or unload within a single compressor band. This allows any number of compressors to run, meeting the goal of optimum control. There are many compressor controllers available on the market, ranging from very simple to very complex and sophisticated.

All of these controls suffer from a significant flaw — not in the controller itself, but in the behavior of the operator. Most controllers require the operator of the compressors to understand the workings of the controller. And due to staff turnover and

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high workloads, there is often little time to read the manual to learn the operation.

There is usually very little training to ensure they understand the manual. And this is where many problems can begin.

If you are running a controller — even one of the best offered in the market today — yet it has been deliberately disabled, it will not properly control the connected compressors. Sometimes, the compressor operator simply cannot understand the control functions — so he might turn it off, causing the compressors to run inefficiently. Purchasing an expensive controller is one thing, but “best practices plants” need to ensure that there is proper training in place, so operators can learn how to use available tools.

THE BOTTOM LINE If your compressor is running unloaded more than 25% of the time, it may be beneficial to evaluate your control strategy.

Proper receiver sizing, better system controls, or upgrading to a more efficient operating mode can dramatically reduce energy waste. Additionally, properly training personnel on compressor and controller functions is critical.

Compressed air is often called the “fourth utility,” but unlike electricity or water, inefficiencies can hide quietly in the background.

Taking the time to understand how your compressor operates may reveal that you’re paying for far more air than your plant actually uses.

FPW

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27

INDUSTRIAL HYDRAULICS

WITH OPTIMIZATIONS OF THEIR DESIGN, VARIABLE DISPLACEMENT PUMPS CAN HELP PROVIDE A 30-50% REDUCTION IN ENERGY WITH DYNAMIC, ON-DEMAND FLOW.

MAGIC

MAKING HAPPEN WITH VARIABLEDISPLACEMENT PUMPS A

S INDUSTRIAL MANUFACTURERS continue to focus on improving efficiency, controllability, and energy usage, variable-displacement axial piston pumps have become an increasingly important technology for optimizing hydraulic system performance. While the core technology has been established for decades, continued advancements in pump controls, variable speed drives, and system integration are helping engineers achieve greater efficiency across a wide range of industrial applications.

In this Q&A, Michael Budda, Senior Industrial Hydraulics Product Engineer at Bosch Rexroth, discusses how variabledisplacement axial piston pumps have evolved, where they provide the greatest benefits, and what OEM engineers should consider when selecting and implementing this technology.

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FPW: What are the biggest benefits for variable-displacement axial pumps?

Budda: The biggest benefit is the ability to adjust the flow rate of the pump to the specific needs of the hydraulic system at that moment. How and when you control that adjustment is where all the magic happens. If you are working with simple pump controls, they can offer the best match to meet the requirements (i.e. machine load and cycle) of your system.

The ability to match the flow rate for when a machine truly needs energy is a big benefit when implementing this technology.

FPW: How does pump displacement control improve machine efficiency during varying load conditions?

Budda: When systems are designed, a main consideration is that not all systems run 100% of load all the time, something that would be very rare. When using a fixed-displacement pump, you have

Edited By Mary C. Gannon, Editor-in-Chief

designed a system that is good for 100% of the load, but any time you don't need that much power, you have to burn it off.

Typically, that extra power (in the form of flow and pressure) is burned over a relief valve and wasted as heat. With a variabledisplacement pump, in its simplest form, you dial back the flow, so you aren't having to waste as much energy as heat.

FPW: How has this tech changed or improved since first launch?

Budda: The core principle of the technology itself has been around for decades for industrial hydraulic companies. However, over the years companies have introduced new pumps with mostly internal improvements and optimizations over years of experience in the field. The key to that variabledisplacement technology — the swashplate design — will likely stay the same for some time. Prior to this, fixed pumps were the main solution.

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BOSCH REXROTH

Optimizing industrial systems can be done easily with variable-displacement axial piston pumps.

INDUSTRIAL HYDRAULICS

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INDUSTRIAL HYDRAULICS

FPW: What role do pressure and flow compensation controls play in optimizing hydraulic system performance?

Budda: Pressure and flow compensation play a vital role in optimization. There is a reason why a vast majority of pumps we sell at Bosch Rexroth to the market are standard pressure and/or flow control, often combined together. I would say nearly 60-70% of the market are these types of controls.

They are a first large step into the variable displacement and eventually variable speed world. They are not the end-all, be-all, but they are simple enough to implement and from a cost perspective, they lower the barrier of entry, especially when compared to something like torque (aka horsepower) controls and electronic controls.

FPW: What applications are best suited for variable displacement pumps?

Budda: Across manufacturing, many have come to accept variable displacement pumps almost as the norm compared to fixed displacement. In general, I see variable displacement being useful in many applications, like industry laundry machines, balers, railway maintenance (MOW), presses, and concrete block machines.

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FPW: How do variable-displacement pumps help reduce overall energy consumption?

Budda: Variable pumps give the ability to provide the energy to the hydraulic system at the point in the cycle when it needs it, rather than traditional fixed displacement systems that burn excess energy. In terms of everyday use, we can think of a fixed pump system like driving a car with the gas pressed down all the way and using your brakes to modulate the speed of your car. You could imagine how much heat and energy is being wasted. With a variable displacement pump, you have the ability to modulate that gas pedal, so when you need more, you press your foot down, and if you need less, you let off the gas. That is the primary reason for how variable displacement can help reduce overall energy consumption of a circuit.

FPW: Where are the biggest benefits in applications like injection molding machines?

Budda: Most injection molding machines now are starting or have started implementing fixed-displacement pumps with variable speed drives. However, there are a few manufacturers that have standardized the

FPW: How much energy savings can machine builders realistically expect when transitioning from conventional fixed-displacement systems to modern variable displacement technology?

Budda: Typically, we see savings between 30-50% reduction in energy when advancing from a fixed-displacement system to variable displacement. The caveat is that this is highly dependent on your machine cycle and load cycle.

FPW: How are variable speed drives and servo-hydraulic systems changing the way axial piston pumps are applied?

Budda: It's interesting because variable speed drives do affect your choice in the pump. It's very common to see fixed displacement pumps in these types of systems, but those are typically within the more dynamic systems. This is mostly because a fixed displacement pump is one less variable to have to think about when selecting a drive. However, when discussing systems that are usually more dynamic, there are limitations with fixed. Another common

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VARIABLE DISPLACEMENT PUMPS ARE THE FIRST STEP TO A BETTER CONTROL LOGIC FOR YOUR SYSTEM AND LOWER THE BARRIER TO HIGHER LEVELS OF TECHNOLOGY, LIKE VARIABLE SPEED DRIVES.

combined concept of a variable-speed drive with a variable-displacement pump. This can give better control of the machine over the whole cycle which often has different but repeatable requirements. For instance, the clamp cycle would often be low or no flow but at a high pressure, while doing the injection would require a different load out of the hydraulic system. The variable speed of the drive along with the variable displacement can be used to optimize for each part of the cycle. This is prevalent with injection molding machines because it's such repeatable cycles.

Another benefit is that with the scalability of the power coming from a hydraulic unit with variable speed and variable displacement you can have one hydraulic unit that can support multiple axis. You can have high cost savings compared to a typical electric drive solution where you would need a separate electric drive for each axis, as you would only need one hydraulic unit to replace several electric drives on one machine.

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approach would be to use variable-displacement pumps. This gives your pump the ability to act like an additional set of "gears" for your hydraulic system. Servo drives are very torque specific — meaning you need to select them based on the torque required for your drive. Having a variable displacement pump is like using a CVT in a car, which perhaps allows you to downsize your drive when you 'flip the switch' on the displacement control of your pump.

FPW: What role do these pumps play in helping manufacturers meet sustainability or carbon reduction goals? Are there noise reduction benefits?

Budda: I have not experienced a company coming to me specifically with the pure intent of reducing carbon, these pumps are certainly a way to help achieve those goals.

If a manufacturing plant is running a lot of machines that are wasting energy over fixed pumps and not optimizing them with variable displacement or variable speed, there is a potential for them to reduce their CO2. How much would really be a case-bycase basis and you can conduct a power system study to see if it would be beneficial.

Another big benefit of these pumps is noise reduction. If you pair a variable displacement pump with a variable speed THE CORE DESIGN PHILOSOPHY OF AN AXIAL PISTON VARIABLE DISPLACEMENT PUMP – THE SWASHPLATE – HAS BEEN REFINED FOR THE MODERN ERA.

drive, this can — in most instances — significantly reduce overall noise levels and also help meet OSHA noise guidelines in some situations.

FPW: How have customer expectations changed regarding hydraulic system efficiency, controllability, and energy usage over the last decade?

Budda: I've seen a lot more focus from engineers on overall efficiency over the years. I'm sure the cost of energy is a big influence on this alongside the advancements in engineering tools such as simulation programs which require efficiencies of components to be inputted into their program. These are additional steps that can be taken to create the most efficient system, which is making this topic and adoption increasingly prevalent in the industry and in the US. FPW: How can proper pump selection influence overall system efficiency and total cost of ownership?

Budda: Choosing the right pump can certainly help with system efficiency. Despite what many may think, pumps do have their own operating range 'sweet spots.'

The point at which their volumetric and mechanical efficiencies result in the best overall efficiency of the pump. But you also need to consider the lifetime of the pump. As an example, running a larger pump slower usually results in an extended pump lifetime, but it might not be the most efficient compared to spinning a smaller pump faster. Other tradeoffs should be considered too, because a small pump spinning fast could have reduced life/longevity and be noisier.

FPW: What should OEM engineers consider when sizing or selecting a variable displacement axial piston pump for industrial machinery?

Budda: The biggest consideration is the tried-and-true basics

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of hydraulics, how much pressure and how much flow do you need. Next, you need to discern what type of pump control is required. In some instances, you can have up to three options on the pump at the same time with different variations.

This can be a tricky point, but companies with a history in various industries can really help. Overall, a vast majority of applications can be lumped into standard pressure control (aka compensation) or flow control basics, but that doesn't mean that if you choose a pressure compensation pump for your system that it will automatically be the best selection. Because there are so many options, the types of controls are often identified in data sheets from companies.

FPW: How important is the relationship between the pump, valves and control architecture in maximizing performance?

Budda: The relationship is quite important; you don't want to marry these solutions together if they don't fit. For instance, oftentimes when a proportional valve is being used in a circuit, the pump control is a secondary layer of control. The proportional valve is the main control valve for the actuator, whether that is force or speed. You don't want the pump control to get in the way of that, so most of the time in that situation you would have a pressure control on the pump. But if you were to have a simple bang-bang valve for direction control of the actuator, then you could up the control architecture on the pump to make it a be more sophisticated to control the force and speed of the actuator.

In the end, choosing the right pump for the circuit is about as important as it can get, especially when you are entering the world of variable displacement. When it's a fixed pump with a fixed drive speed, you don't have a lot of options to consider on the pump control, because there are none, but you should think about how much energy you could be wasting.

FPW

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