Insane Hydraulics
Bold and audacious blog about fluid power
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Adding two lists to the seals database: List of Seals for Rexroth A10VO140..3X Hydraulic Pump, and List of Seals for Rexroth A10VO45..3X Hydraulic Pump.
Virtually all components that I repair contain seals, and every overhaul warrants their replacement. I try to use original seal kits whenever I can, but it's not always possible (or feasible) due to logistical and/or economic reasons. In such cases, I order seals by size and try to reuse proprietary stuff (metal gaskets, etc...). Since I have been trying to implement the DRY philosophy as much as I can (DRY for Don't Repeat Yourself) I realized that my seal ordering/quote-requesting process is flawed (due to my absolute inability to stay organized). For example - whenever I need to request a quote for, say, a set of ORFS o-rings, I either hunt for an old similar e-mail of mine to copy, or look for the catalog page with the o-ring sizes, and then (slowly) compose a list of o-rings that I can send to a supplier for a quote. Not ideal, to say the least. So, I decided to shamelessly employ the powers of Javascript to make my e-mail orders/quote requests easier to compose - and thus a new Library section was born - the Hydraulic Seal and Seal Kit Database. I've already put there the list for the o-rings that I order the most - ORFS, SAE flange, SAE ORB (o-ring boss) O-rings. But I will be filling the collection up as I go (I have some A10VOs in the shop "aligned" for this week, so stay tuned for brief updates). This section will help me keep these seal lists organized in a single place which I can always reach wherever I am, and, hopefully, it may be of use to some of you as well.
Useful pressure-drop data in Measuring Low Flow Rate With a Needle Valve. And also - a Happy New Year to all! 2025 is going to be the year! So stay strong, stay on course, and never forget about your dreams!
We haven't had a full weekend for the last month and a half due to "usual end of the year routines" (think - stock inventory), and when I said to my wife today: "Finally, we are getting a full weekend before Christmas..." - something hydraulic broke somewhere - and... I am spending this Sunday troubleshooting a core-drilling rig in a mine, which makes me seriously wonder if my smartphone is tapped by a secret society that does not want to see me ever take a break... Anyhow, the Holiday Season is upon us once again, and before anything else - I want to thank you for being here and wish you all a Merry Christmas! I did more "housekeeping" today, and as of now, there are only 9 old posts in the Let's Talk Hydraulics section that require refactoring for the HTTPS standard. I am almost there! So, presenting to you the new and improved tales about:
A short "emergency pressure discharge" story from my past in Workshop Rage, and
A troubleshooting episode that involved a piece of tactical gear in Solenoid Valves, Hydraulic Jacks, Low Voltage and Broken Doors
How (Not) to Remove a Spring Pin From a Blind Hole
A Hand Pump as a Diagnostic Tool?
Rexroth M4-15 - The Loose LS Shuttle Seat Strikes Again!
Playing Russian Roulette With a Hose Cutter
If you ever see yourself in need of repairing a SensorJunior gauge damaged by leaked batteries - this post can steer you in the right direction - Saving Private Gauge.
I make another tool from scrap, then conduct an unsafe experiment, and as usual, get side-tracked pretty badly in - DIY Wrench for Gland Nuts of Hydraulic Cylinders.
A couple of "business revelations" that I learned the hard way, in Business Lessons From a Grease Monkey.
I would like to talk about two important details I forgot mention in my post on Komatsu LPD 45+45 pump from PC88MR-6, discuss an interesting matter raised by a reader, and also leave a small tip on how to determine the correct o-ring width for a boss seal with a 45ยบ chamfer - in Komatsu LPD45+45 Pump from PC88MR-6 Excavator - Additional Information.
Today I will tell you another story of how I fixed something - but please, do not consider this as a guide on what to do - it's rather a "I don't believe it freaking worked!" kind of story about what not to do! - Fixing a Gear Flow Divider Without Parts.
How About Them Gear Flow Dividers?
Today we save a grader, learn a valve, and even use a John Wick reference in No Variable Displacement Pump - No Problem!.
Komatsu LPD45+45 Pump from PC88MR-6 Excavator.
Fate intervened and apparently, I'll be making a two-article Komstsu series - today's post would be the starter, with the main course to be served next week - Komatsu PC88MR-6 Pump Stalling the Engine.
A 4SH-20 hose that I made failed... Twice in a row!.. I am definitely not used to that! So, here's what I think about it in - I Got Tricked by a Bad Hydraulic Hose.
DIY Tool for Measuring Width of Internal Grooves.
Before anything else - an add-on to the last week's post - a reader sent me an email, pointing out the existence of basically the same T-11A reducing valve but with a drilled orifice. I wasn't aware of that, and I must say that I love getting such emails! The part number would be PPDF8, and it is called "Pilot-operated, pressure reducing/relieving main stage with drilled piston orifice and integral T-8A control cavity". As for today - I got another "orifice story" for you, about the Danfoss H1B Hydraulic Proportional Control Leakage.
I Wonder if this Orifice Design is "Not so Good" After All...
A perfect illustration to this month's post on pump killers from a call I did just this Friday - Priming Troubles.
I finally managed to test the flowmeter that I tore down the other day - Testing the Webtec FI750-120ABOT Variable Orifice Flowmeter
Three Plus One Overcenter Valve Types a Tech Must Know
If this post saves a single hydraulic pump from going to scrap - my mission is completed! - The Most Innocent-Looking Hydraulic Pump Killer
Today, I am enhancing the Overcenter Valve Calculator Page: I've added comments on how the calculations are made, as well as some "counterbalancing bullet points." The interactive diagram now shows the formulae and also changes the cylinder symbol to a hydraulic motor symbol when the ratio is set to 1:1. Please refresh the page to visualize the changes if you already visited it last week.
This app calculates the opening pilot pressure of a non-balanced external-pilot-operated over-center valve - no explanation today, just the app, more on the subject (and possibly a refactor) next week: External-Pilot-Operated Over-center Valve Calculator
The good old "step back and breathe" maneuver in Troubleshooting No Movement in a Closed Center Load Sensing System.
Tear-down of Webtec FI750 Variable Orifice Flow Indicator
Three "CETOP 3 Oh-Oh Moments" in the Life of Every Hydraulic Technician
A Couple of Things That Can Throw a Tech Off Guard
An unscheduled assistance call brought up a peculiar failure, variants of which I've already seen many times before, and I describe it the best I can in - I Always Carry These Tiny Parts in my Toolbox.
A couple of tips on Manual Match-Lapping of Cylinder Blocks and Valve Plates of Hydraulic Pumps and Motors
A small training session on pressure units in Bar, Mpa, Atm, and an Almost Ruptured Hose.
I realize that people who are used to Eaton orbital steering valves will find no news in this article, but folks like me, who deal exclusively with classic Danfoss units may find it surprising that Two Steering Valves With Equal Displacements Can Produce Very Different Steering Speeds.
Strange Behavior of Danfoss 155G4074 PVEH Electro-Hydraulic Actuator
Today's post is a rant from a person who spent the last eight days replacing old hoses with new hoses and old HPUs with new HPUs - Random Advice for Aspiring Hydraulic Technicians.
Well... I must confess that a week underground doing double shifts does take its toll... Yet I still somehow managed to finish my interactive nomogram - and now it has three flow ranges, the possibility to switch between gallons US and UK, and the recommended flow velocity highlights. Due to how much modern browsers (especially mobile) like caching, you may need to go to the options, and clear the browsing history to visualize correctly the updated page - Interactive Nomogram for Sizing Hydraulic Hoses.
Several days ago, when I was in the field, I needed to quickly ballpark the correct size for a hydraulic line, and I pulled out my phone and opened a page that I created a long time ago for this very purpose. The page was supposed to have an interactive monogram, where one would push about a virtual ruler, and get the necessary figures on the spot (yes, I do have a soft spot for monograms, slide rules, and other types of mechanical calculators). I immediately saw that the page does not work well with mobile devices (especially phones, and especially in vertical orientation), and so I decided to do a major upgrade: instead of using a static image and a piece of code for moving a line, I wrote a program that draws the nomogram parametrically (in other words creates the lines in the code), which turns it into a very precise tool, and allows you to change the scale, or the annotations of axes dynamically - for example, change the flow range from 3...400 l/min to, say, 400...1000 l/min, or replace the US gallons with UK gallons. Now, I haven't implemented the range/units feature yet - because the annual maintenance stop in the mine has been taking up pretty much all of my free time - but I should be able to finish it this week (if I survive through it...). I did manage to write a boilerplate that works within the flow range of the old nonogram (400 l/min). What makes it even cooler is the fact that the numbers that are displayed above the ranges are actually the "geometric" numbers - i.e. derived from the coordinates of points where the ruler line crosses the range lines, but the speed figures at the bottom of the nomogram are calculated - and you can see they are spot on! So, please, check it out, and, if possible, see if it works well on your mobile devices (if you already use this page, you'll need to refresh it to get the latest version) - any feedback will be greatly appreciated: Interactive Nomogram for Sizing Hydraulic Hoses.
A Test Bench - The Best Place to Learn Pump Troubleshooting.
Today's blog is a heads-up to all pressure filter users - I am talking about not one - but two high-pressure filter failures, one of which I've seen many times, and the other one only once - it turned up last week and, frankly speaking, puzzled me so bad that I feel I must document it - Strangest Failure of a Pressure Filter Element.
This was supposed to be a short post, but as is always the case, I got "carried away" and a three-paragraph article turned into a multiple-page rant... - Let's Talk About Hydropneumatic Accumulators (Part 3) - Getting Real
Let's Talk About Hydropneumatic Accumulators (Part 2)
My (Latest) Thoughts on Aftermarket Spares for Hydraulic Pumps and Motors.
Exploring the Design of a Low-Cost 100-bar Digital Pressure Gauge.
Testing Another Cheap Digital Pressure Gauge Kit.
This week I opened yet another 15000 hour+ PV180 (impaired by unscheduled "hydraulic fluid enhancement" with generous amounts of water), and I, once again, found a "sneaky" failure that I've seen before (on this and other pump series). I feel I need to address it again in Something You Should Know Before Overhauling a Parker PVplus Pump.
The Most Embarrassing Mistake of My Career as a Hydraulic Technician.
Not so long ago I described how I had to set the neutral of several large closed-loop pumps, and I mentioned a "secret technique" that I used on the pumps and said that I would reveal it one day. Well - today is the day, and I present to you an "alternative centering technique" in Setting Hydraulic Pumps With Lasers
Some details of The Analog Front End of the Cheapest Digital Pressure Gauge.
Adding another myth to the collection - Bigger Motor Displacement Automatically Guarantees Bigger Torque.
A Simple Way of Protecting DIY Steel Parts From Rust.
Testing the Cheapest Digital Pressure Gauge I Could Find
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