Insane Hydraulics
Bold and audacious blog about fluid power
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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.