Hey there! If you’re dealing with HAWE hydraulic pumps, you probably know how crucial it is to keep reverse flow from ruining your system—whether you’re running a mobile crane, an industrial press, or a fleet of mining equipment. As a HAWE pump supplier who’s been on the ground for years, I’ve seen first-hand what happens when reverse flow slips through: unplanned downtime, component wear, even whole-system failures that cost way more than fixing the issue upfront. This isn’t just a “set it and forget it” thing—reverse flow in HAWE pumps isn’t some obscure myth, it’s a real problem that pops up when you cut corners or skip basic checks. Let’s break down how to stop it cold, no fancy jargon, just straight talk that works for actual technicians and operators. HAWE Pump
First, let’s get on the same page: what is reverse flow anyway? For anyone new here, it’s when fluid moves backward through your HAWE pump instead of the direction you need it to. Usually, this happens because of pressure differences—like when a load on a hydraulic cylinder suddenly drops, creating a backflow that pushes fluid back through the pump’s inlet. HAWE pumps (especially their axial piston and vane models, which are super popular) are designed for unidirectional flow, so reverse flow doesn’t just mess up the pump itself—it can damage valves, hoses, and even the prime mover. I’ve had customers tell me their pump’s internal parts wore out in half the expected time because reverse flow was going unchecked. That’s avoidable.
Now, the number one fix for reverse flow in HAWE pumps: make sure your directional control valves (DCVs) are sized and installed correctly. Wait, I know what you’re thinking—“Everyone says that, but why does it matter so much for HAWE specifically?” HAWE’s DCVs are precision-made to match their pump’s flow rate, so if you grab a generic valve from the hardware store (no shade, but it’s true) that’s either too small or too big, you’re begging for backflow. Too small, and the valve can’t hold pressure fast enough when your system cycles, letting fluid slip backward. Too big, and there’s dead volume in the valve that creates pressure spikes that trigger reverse flow. Last month, a guy from a construction company hit me up saying his HAWE V60N pump was reversing during boom extension—turns out his tech had swapped the original HAWE DCV for a cheaper one that was 2mm too wide. Swapping it back fixed it overnight. Pro tip: always match the DCV’s Cv rating (that’s flow capacity) to your HAWE pump’s maximum flow. If you’re not sure, just shoot me a message—no need to overthink it.
Next up, check your check valves (also called non-return valves) for HAWE compatibility. These are the “one-way gates” in your system, and they’re your first line of defense against reverse flow. But not all check valves work with HAWE pumps. A lot of off-brand check valves leak at the seal, so even if they’re in line, fluid creeps backward. HAWE makes their own inline check valves that are tested to handle the exact pressure spikes their pumps produce, so if you’re using a third-party one, you’re taking a risk. Wait, but I see this a lot: people install a check valve, but they put it on the wrong side. If it’s on the inlet instead of the outlet, you’re just trapping air, not stopping reverse flow. I once had a farmer come to me with a HAWE pump for his grain auger—his check valve was backwards, so every time he turned the pump off, fluid ran back into the reservoir. That’s a dumb easy fix, but it’s super common. Also, make sure your check valve’s cracking pressure (the minimum pressure needed to open it) is right. If it’s too high, your pump has to work harder, which can lead to overpressure that causes reverse flow; too low, and it opens too easily, letting backflow through. For HAWE’s medium-pressure pumps (like the V30 series), a cracking pressure of 0.5 bar is sweet spot—no more, no less.
Then there’s pressure relief valves, and yes, they tie into reverse flow. I know, pressure relief is for overpressure, but hear me out: if your system’s relief valve is set too low, it can trigger reverse flow during a sudden load drop. HAWE pumps generate consistent pressure, so if your relief is calibrated for a lower number, it’ll “relieve” pressure by letting fluid backflow through the pump. A lot of people use a generic relief valve that’s not matched to their HAWE pump’s pressure rating. For example, a HAWE Pump with a 350 bar max rating needs a relief valve set to 320–330 bar, not 250 bar. If you set it lower, you’re basically inviting reverse flow when the system cycles. Last week, a manufacturing plant’s line went down because their relief valve was set too low on a HAWE C60 pump—backflow damaged the cylinder seal, and they lost 8 hours of production. Calibrating your relief valve to match your HAWE pump’s specs is non-negotiable.
Now, let’s talk about installation and mounting, because even the best parts won’t work if you mess up the setup. HAWE pumps have specific orientation requirements, especially axial piston models. If you mount the pump incorrectly—like tilting it too far from its recommended angle (usually +/-10 degrees from horizontal for most models)—the internal pistons can move unevenly, creating pressure imbalances that lead to reverse flow. I once saw a pump mounted sideways on a mobile truck crane—after a week, reverse flow started, and the piston wear was visible just from the angle being off. Also, make sure your inlet line is sized right. If it’s too small, cavitation happens, which creates low pressure on the inlet side, pulling fluid backward through the pump. HAWE’s guidelines say inlet lines should have a flow velocity of 1–2 m/s for their pumps—any faster, and you’re asking for cavitation and reverse flow. I’ve had a few customers use ½” inlet lines on a HAWE V60N (which needs ¾”) and that’s exactly what caused their reverse flow issues. Fixing the line size and mounting angle was all it took, no new parts needed.
Another thing that’s easy to overlook: fluid contamination. Hydraulic fluid is the lifeblood of your HAWE pump, and if it’s dirty, it can gum up internal components like the poppet in check valves or the spool in directional valves. A gummed-up check valve won’t close all the way, so reverse flow happens. A spool stuck in the middle will let fluid move both ways. I see this all the time—customers skip regular fluid changes, and after a few months, reverse flow pops up. HAWE recommends using ISO 46 or 68 hydraulic fluid (depending on the model) and changing it every 1000 operating hours, plus replacing the filter every 500 hours. Last month, a mining company’s HAWE pump started reversing, and when we checked the fluid, it had metal shavings from a worn filter. Flushing the system and replacing the filter fixed the reverse flow in a day. It’s not just about keeping your pump clean—dirty fluid is a silent cause of reverse flow.
Wait, what about when reverse flow is from the pump itself, not the rest of the system? Rare, but it happens. HAWE pumps have internal seals and valve plates that wear out over time, especially if you’re running them at maximum pressure 24/7. If the internal valve plate is scratched, it can’t direct flow properly, so backflow occurs. Or the inlet check valve inside the pump (yes, most HAWE pumps have an internal one) is worn, so it leaks. How do you tell if it’s the pump vs. the rest of the system? Disconnect the hoses from the pump and run it idle—if fluid still flows backward, it’s the pump. If not, it’s your valves or lines. For internal wear, you don’t have to replace the whole pump—you can swap out the valve plate and internal seals, which is way cheaper. As a HAWE supplier, I stock all the replacement parts for their common models, so you don’t have to wait weeks for a custom order.
Now, let’s talk about common mistakes to avoid. First, don’t “rig” a fix. I’ve seen people tape a check valve in or use a random valve from a different brand to save money—it works temporarily, but it’ll cause more reverse flow later. HAWE parts are engineered to work together, so using generic parts is a risk. Second, don’t ignore small signs. If your system is a bit slower than usual or you hear a weird whining noise when you turn the pump off, that’s reverse flow starting. Fix it early, and you won’t have to pay for a whole new pump. Third, don’t skip routine checks. Every month, do a quick inspection of your valves, lines, and fluid—even 10 minutes can catch reverse flow before it causes damage.
Let me wrap this up with a quick real example. A customer who runs a fleet of 12 HAWE V30 pumps for their dump trucks was having reverse flow issues on 3 of them. They tried swapping valves, checking lines, but nothing worked. We did a quick check: their relief valves were set at 280 bar, but their pumps max out at 320. Calibrating those valves to 310 bar fixed all 3, and they saved $10k in potential pump repairs. That’s the thing about HAWE pumps—they’re super reliable when you work with their specs, not against them.
At the end of the day, preventing reverse flow in HAWE pumps is about matching your components, installing them right, and keeping your system clean. It’s not rocket science, but it does take paying attention to details that a lot of people skip. If you’re dealing with reverse flow and you’re not sure what’s going on—whether you need help sizing a valve, checking your pump’s internal parts, or just replacing a worn check valve—hit me up to connect and talk through your specific setup. I’ve worked with all kinds of HAWE pump models, from mobile to industrial, so I can point you in the right direction. Don’t let reverse flow mess up your operation—fix it before it’s a big problem.
YUKEN Pump References
HAWE Hydraulics. (2022). Installation and Operation Manual for Axial Piston Pumps.
Hydraulic Institute. (2021). Guidelines for Hydraulic System Fluid Contamination Control.
HAWE Hydraulics. (2023). Directional Control Valve and Pump Compatibility Guide.
Mobile Hydraulics Association. (2022). Best Practices for Preventing Reverse Flow in Mobile Hydraulic Systems.
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