You've built the perfect system on CETOP blocks, protected it with precision filters, and cushioned it with accumulators. All of this is in vain if the heart of the system – the hydraulic pump – doesn't keep up with your needs.
Many designers, out of habit (and for savings), reach for classic, aluminum gear pumps. And rightly so, because for simple tasks, they are indispensable. But what if your machine needs to operate under an extreme pressure of 350 bar, runs 24 hours a day, or you're struggling with boiling oil?
BRhydraulic experts have taken a close look at the two most popular solutions on the market. Find out why in heavy industry, a standard gear pump is not enough and discover the magic of piston pumps.
1. Gear pump – a reliable workhorse
Its operating principle is extremely simple: two meshing gears rotate inside the casing, transporting oil from the inlet to the outlet.
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Advantages: It is inexpensive, small, light, and very resistant to contamination. If you are building a simple log splitter or a small lift – this is the ideal choice.
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The Dark Side: Gear pumps have constant displacement. This means that with each rotation of the engine, they deliver exactly the same, maximum amount of oil. What happens when your machine doesn't need oil at a given moment (because the cylinder is stationary), but the engine is still running? This entire powerful stream of oil is forced through the relief valve back to the tank. The result? The engine loses power, fuel disappears before your eyes, and the oil starts to boil! Additionally, gear pumps usually fail at pressures above 250 bar.
2. Piston pump – a revolver cylinder under pressure
When we enter the world of powerful industrial presses, large excavators, and heavy injection molding machines, the piston pump (most often axial) steps onto the scene.
Its interior resembles a revolver cylinder. It contains a rotating cylinder block in which steel pistons are mounted. These pistons slide along a so-called swash plate. This is an absolute engineering masterpiece that can easily generate a murderous pressure of 350, or even 400 bar. These components are made of such hard alloys and with such microscopic precision that their lifespan far exceeds standard solutions.
3. Variable displacement (Load Sensing) – no more wasted energy!
What makes piston pumps a true revolution is the ability to smoothly change their displacement in real time. How does it work?
The angle of the aforementioned swash plate (on which the pistons slide) can be varied.
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When the plate is heavily tilted, the pistons work at full stroke – the pump delivers 100% of the oil.
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But when the operator releases the joystick and the machine doesn't need pressure, a special mechanism (called a compensator or Load Sensing system) immediately straightens the plate to zero.
The pistons stop extending! The pump still rotates with the engine, but delivers exactly 0 liters of oil. It consumes a fraction of the power, doesn't choke the engine, and doesn't heat the fluid. It is this intelligence that makes modern machines burn 30% less fuel and not require gigantic coolers.
Summary
The choice of pump determines the characteristics of the entire machine. If you are looking for a budget-friendly and simple solution – a classic gear pump will meet your expectations. However, if you are looking for extreme pressure, a lifespan measured in tens of thousands of hours, and energy efficiency – investing in a piston pump will pay off faster than you think.
Are you planning to build a new power unit or want to modernize your machine's drive? At BRhydraulic, we supply both proven gear pumps and advanced variable displacement piston units. Contact our engineers – we will choose the heart that perfectly matches your system!
