By Donna Pollander

I recently had the pleasure of sitting in on (and facilitating) a webinar led by Mark Redmond, an IFPS-certified fluid power instructor, titled Understanding Variable Pump Pressure Compensation in Hydraulic Systems. Now, I’ll admit—anything with “pressure compensation” in the title doesn’t exactly scream comedy. But stick with me. Hydraulics, much like life, is all about balance, efficiency… and not overheating under pressure.

Mark kicked things off with the fundamentals of hydraulic pumps, reminding us of a deceptively simple truth: pumps don’t create pressure—they create flow. Pressure is what happens when that flow meets resistance. It’s a bit like my morning routine: I generate plenty of motion, but it’s the resistance (emails, deadlines, existential questions before coffee) that creates the pressure.

We explored the two main pump types: centrifugal and positive displacement. Centrifugal pumps are great for moving fluids but not for building pressure—think of them as enthusiastic but noncommittal coworkers. Positive displacement pumps, on the other hand, deliver consistent flow regardless of pressure, making them the real workhorses of hydraulic systems.

Measurement came next. Positive displacement pumps are rated by how much fluid they move per revolution. In modern systems, thanks to high volumetric efficiency, flow comes down to displacement and shaft speed. In other words, it’s not just how hard you work—it’s how efficiently you spin.

Then came the classic matchup: fixed vs. variable displacement pumps. Fixed displacement pumps are reliable and straightforward, ideal for single-function systems like a trash compactor—steady, predictable, no surprises. Variable displacement pumps, however, are the multitaskers. They adjust flow without changing speed, making them perfect for systems with multiple demands. If fixed pumps are a flip phone, variable pumps are a smartphone with 47 open tabs (very similar to my smartphone).

Mark’s explanation of the swash plate mechanism was a highlight. By adjusting the angle of the swash plate, the pump controls how much fluid is moved. At full angle, you get maximum flow; at zero angle, the pump essentially takes a break. If only we could all adjust our “swash plate angle” on a Monday morning.

The real magic, though, lies in pressure compensation. A pressure compensator ensures the pump only produces the flow needed to maintain a set pressure. It’s the hydraulic equivalent of knowing when to stop pouring coffee into your cup before it spills—efficient, controlled, and slightly heroic.

We also touched on advanced controls like load sensing and torque limiting, which help systems adapt to demand without exceeding power limits. And for those who like their hydraulics with a side of tech, electronic displacement control offers precision through proportional valves and signals—because even pumps are going digital now.

Of course, no system is complete without safety. Mark emphasized the importance of properly sized relief valves, ideally set about 500 PSI above the compensator. Set them wrong, and you’re essentially converting energy into heat—fast. It’s like running a marathon in a winter coat: technically possible, but wildly inefficient and likely to end badly (for the record, I DON’T run marathons).

One of the most eye-opening comparisons was between fixed displacement systems and pressure-compensated ones. The former can waste significant energy, while the latter adjusts output to demand, reducing horsepower requirements and improving efficiency. Less waste, less heat, more sense.

We wrapped up with remote compensators and multi-pump coordination—topics that sound niche but are crucial in complex systems. The key takeaway? Whether you’re managing one pump or many, communication and proper settings matter. (Again, life lessons everywhere.)

All in all, it was a fascinating session that proved hydraulics isn’t just about moving fluid—it’s about working smarter, not harder. And if nothing else, I now have a newfound appreciation for systems that know how to handle pressure better than I do.

The recording of this webinar—along with more than 100 other educational videos—is available on the IFPS website, free to members.