Fluid Power Forum — Advancing People, Technology, and Application.
New Zealand Edition Seven · Vol 2 Issue 2 · April 2026 · Bay of Plenty.
From the Editor
Things are moving on a few fronts. Between editions, a good portion of the bench time has gone into developing structured hydraulic training curriculum. The goal is practical, trade-focused training built around what technicians actually encounter in the field, not textbook theory for its own sake. It’s early days, but it’s taking shape. More detail to come when there’s something worth reporting.
This edition introduces the Fault File, a new section built around real faults from real machines. The first submission came in as a video. If you’ve got something worth sharing, send it through.
Keep the questions, confessions, and fault finds coming.
— Shane
Member Letter
A member recently sent in a video of an incorrect fitting found on a machine after chasing a persistent leak. Good find, and exactly the kind of thing this forum exists to share.
If you’ve got video or photos worth sharing, the simplest way is to attach them directly to your email. If the file is too large, get in touch and we’ll work something out.
Feature Article — Sustainable Coating Extends the Life of Hydraulic Piston Rods
Ovako Cromax · Mattias Awad, Head of Marketing and Technology
Hard chrome plating on piston rods is effective, but hexavalent chrome (CrVI) is on the regulatory watchlist under the REACH directive. Industries are being pushed to find alternatives, and the options available until recently involved trade-offs on hardness, seal compatibility, or installation.
Ovako Cromax has developed NiKrom III, a trivalent chrome (CrIII) coating that keeps the nickel underlayer from their existing products but replaces the hexavalent chrome with a process considered safer and less toxic to produce. The practical appeal is that it drops into existing cylinder designs without modification. Same surface hardness, same friction properties, compatible with existing seals. No additional heat treatment required on the base steel.
Field trials with Sandvik Mining and Rock Solutions in copper mines, where saline atmosphere accelerates corrosion, showed NiKrom III cylinders lasting up to five times longer before showing any sign of corrosion compared to standard CrVI-coated rods.
Currently available in diameters from 20mm to 140mm, lengths up to 3 metres, with production volumes increasing through 2026.
Worth keeping an eye on if you’re specifying cylinder rods for outdoor, coastal, or chemically aggressive environments. The regulatory direction on hexavalent chrome is only going one way.
Read the full article at Fluid Power Journal.
Feature Article — Fluorescents Shine a Light on Leaky Hydraulic Systems
Hydraulic leaks cost more than the fluid you’re replacing. Factor in downtime, cleanup, disposal, wages, and lost production, and a few drips start looking expensive fast. External leaks are also an environmental and safety issue: fluid on the floor is a slip hazard, and fluid in the ground can mean fines.
Two types to understand: internal leaks, where fluid bypasses worn components inside the system and never shows on the floor, and external leaks, where fluid escapes the system entirely. Internal leaks are the harder ones to find. A flow meter installed at key points in the circuit is your best diagnostic tool for tracking them down.
For external leaks, fluorescent dye detection is worth having in the kit. A small amount of UV-compatible dye goes into the reservoir, circulates through the system, and any leak point glows under a UV flashlight. Non-invasive, and useful on any closed-loop system. In machines with multiple fluid types, different dye colours identify which reservoir is the source.
The basics still matter. Regular pressure checks, fluid level monitoring, and marking leaks for corrective action at the next service. Don’t just top up and move on. The contamination stays in the system and the damage compounds.
Read the full article at Fluid Power Journal.
Feature Article — How Flow Meters Play a Vital Role in Automation
Turbines R&D · Mark Weiss, Marketing Specialist
Flow meters don’t get much attention until something goes wrong. But in any automated system that moves fluid, they’re the data source everything else depends on. Without accurate flow measurement, closed-loop control doesn’t work.
The basic job is straightforward: measure the volume or mass of fluid moving through the system and feed that data to the controller. The controller then adjusts valves, pump speed, or mixing ratios in real time, without waiting for a human to notice something is off.
For hydraulic systems specifically, a flow meter in the oil supply line lets the controller monitor actuator speed, detect viscosity changes as oil temperature rises, and flag leaks or blockages before they become failures. On a high-speed press or any application requiring repeatable cycle times, that real-time feedback is the difference between consistent output and scrap.
Meter selection depends on the application. Turbine meters suit clean, steady flows. Coriolis meters handle varying fluid density. Magnetic meters work well in water-based applications where access is limited. Ultrasonic meters are the option when nothing can go inside the flow path.
The trend is toward meters with built-in remote monitoring and self-diagnostics. Less reactive, more predictive.
Read the full article at Fluid Power Journal.
Workshop Gremlin Update — Rexroth A10V Charge Pump Failures: The Conversation Continues
Following last edition’s Gremlin on A10V pumps failing in charge pump applications, member Brad came back with a pointed response. Brad’s position challenges some of the conclusions drawn and raises valid questions about whether the retainer plate failures were design-related or application-specific.
It’s a fair challenge, and the kind of technical pushback that makes this forum worth running.
A technical inquiry has been sent to our Rexroth contact outlining the full system details and the member’s case. We’re still waiting on a response. When it comes, we’ll publish it in full.
Watch this space.
Workshop Confession — The Seal That Kept Coming Back
A travel motor on a mobile machine developed a weeping shaft seal. Straightforward job. Seal replaced, machine back in service.
Two weeks later, same seal, same motor, weeping again. Seal replaced again. It came back a third time.
By that point someone decided to find out why rather than just keep replacing it. The case drain line on that motor had been plumbed into the return line at commissioning instead of direct to tank. Every time the machine was working hard, return line pressure was feeding back into the motor case. That back pressure was loading the shaft seal from the inside, and the seal was never going to hold against it.
The plumbing had been wrong from day one. The machine had run like that for years. Nobody questioned it because nobody had a reason to look until the seal became a recurring job.
Case drain lines go to tank. Not return. Not close enough to return. Tank.
No names. We promised.
Been there? Send yours. Anonymity guaranteed.
Fault File · New Section — Real Faults, Real Machines
The Fault File is a new addition to the forum. The idea is simple: real faults, real machines, what was found and what fixed it. No textbook scenarios.
The first submission came in as a video of an incorrect fitting found after a machine had been leaking for an extended period. A good reminder that the simplest explanation is often the right one, and that a persistent leak is always worth pulling apart properly rather than just retightening.
More details and the video in the next edition once it’s formatted.
Got a fault to share? A photo, a video, a circuit snippet, or just a good story. Send it to the usual address.
Old Fitter Trick — Check the Coil with a Screwdriver
Before pulling a solenoid coil off to test it, try this first. Hold the shaft of a steel screwdriver near the end of the coil while the valve is energised. If the coil is working, you’ll feel the magnetic pull on the screwdriver. No pull means no field. That tells you whether the fault is electrical before you start chasing hydraulics.
Works on any DC solenoid valve. No special tools, takes five seconds, and saves pulling the coil off for nothing. Every fitter should have this one in the kit.
New Technology — Designing a Fluid Conveyance System That Lasts
Parker Hannifin · Matthew Brink and Kevin Haselius, Application Engineering
Most fluid conveyance failures come down to one of three things: wrong components, poor installation, or a design that nobody stress-tested before it went into service.
Parker’s application engineers break selection down using the STAMPED acronym: Size, Temperature, Application, Media, Pressure, Ends, and Delivery. Get all seven right and you have a system that runs. Miss one and you’re looking at leaks, pressure loss, cavitation, or worse.
Common Errors: Undersized inlet plumbing causes cavitation. Sharp bends cause turbulence and pressure drop. Hose twist during assembly is a common cause of early failure: always use two wrenches.
Safety Note: Pinhole leaks in high-pressure lines are a high-pressure injection hazard. Not a paper cut situation. Treat any weeping joint as a hazard, not a nuisance.
Read the full article at Fluid Power Journal.
Workshop Resource — Know Your Solenoid Coils
Source: Insane Hydraulics
If you’ve ever condemned a solenoid coil with a multimeter and then found it worked fine on the bench, this one explains why. There are three types of AC solenoid coils you’ll encounter in hydraulic work, and they behave very differently under test.
True AC coils run on alternating current and rely on inductive reactance to limit current. Standard in older relay-logic panels, rare today. They draw massive inrush current, burn out if the plunger doesn’t reach full stroke, buzz without a shading ring, and create power factor problems. Avoid them.
Fake AC coils are marked as AC but are DC coils with a built-in full-wave rectifier. A multimeter in resistance mode will read very high resistance, sometimes into megaohms, because the test voltage won’t open the rectifier diodes. Switch to diode mode and check for a 1.4V drop across the bridge. That confirms the rectifier is intact.
Super-Fake AC coils turn up on cheap aftermarket valves. Instead of a full-wave bridge, a single series diode. Half-wave rectification, runs hot, and only works with voltage applied in the correct direction. Found on Chinese-made NG10 valves. Worth knowing if you’re sourcing replacement coils on price.
The takeaway: For any industrial installation, use 24VDC coils. The AC variants bring problems the DC versions simply don’t have.
Full article at Insane Hydraulics.
Head Scratcher · Accumulator Safety
You’ve just finished servicing a hydraulic system fitted with a gas-charged accumulator. The hydraulic pressure gauge reads zero.
Is it safe to start disconnecting lines?
- a. The gas may still have stored energy
- b. The nitrogen pressure will also be zero
- c. It is safe to remove the end cap
- d. Compressed air can be used to replace the nitrogen
- e. The bladder has ruptured and must be replaced
Answer next edition. Send your answer to tga.mc.exchange@gmail.com.
Beer O’Clock
Tools Down · Throttle Down · Hydraulics Can Wait.
Friday 24 April 2026, from 5:00 PM. Fluiconnecto Workshop, Bay of Plenty.
What’s Happening
Beer O’Clock · 24 April. Tools down from 5pm at the Fluiconnecto workshop. Come as you are.
HMTTL Hydraulic Repair Facility · Coming Soon. Big news for the Bay. HMTTL is opening a dedicated hydraulic repair facility, and it will be the largest in the Bay of Plenty. The shop will be fitted with state-of-the-art honing equipment, dedicated cylinder strip benches, and the most technologically advanced pump, valve, and motor testing station in the region. This isn’t a corner of an existing workshop cleared out and called a repair bay. It’s a purpose-built facility designed to handle serious hydraulic repair work properly. More details on the opening date to follow.
Australasian Fluid Mechanics Conference 2026 · Christchurch. 6 to 10 December 2026, University of Canterbury. Academic rather than trade, but the biggest fluid mechanics gathering in this part of the world. Worth planning ahead if you’re interested. afmc2026.org
Got Something Worth Sharing? We Want to Hear From You
Fault File. A real fault with a real fix. Photo or video welcome. De-identified.
Old Fitter Trick. A technique or field test that actually works. No special tools required.
Workshop Confession. We’ve all been there. Send yours. Anonymity guaranteed.
Fluid Power Forum · Edition Seven · Vol 2 Issue 2.
Bay of Plenty, New Zealand · April 2026.
tga.mc.exchange@gmail.com