Hydraulic Cylinder Rod is Stuck and Bend Due to the Hitting of Heavy Stone | Check How it's repaired
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Publicado 2022-04-01
I also explain that bent rods can, in many cases, be successfully straightened and re-used. Provided they can be straightened to within the allowable tolerance. One of our members who works for a cylinder repair company, sent me his counter position on this:
"In our experience, 'straightened' rods are never really straight. They almost always have an S curve in them after straightening has been attempted - because they do not re-bend in the same place they originally bent. Using these bent 'straightened' rods greatly compromises the column strength of the cylinder, and is unsafe for a heavily loaded cylinder. It also wears unevenly on the gland and rod bearing, and frequently doesn't seal well. For these reasons, we never try to straighten or reuse a bent rod. I would urge you to rethink your advice on straightening hydraulic cylinder rods."
I respect Don's viewpoint. I just happen NOT to agree with it.
Before I explain why, let's clarify what I mean when I say "bent" and "straight". I'm not talking about bent like your elbow. I'm talking about a deflection that's only detectable with a dial gauge. In this context, a rod is "bent" when it's run-out is outside allowable tolerance, and "straight" when within allowable tolerance.
Now, here's why I don't agree with Don. Many years ago, I worked for a company which repaired a lot of cylinders off mining-size hydraulic excavators - 250 tons operating weight and above. So we're talking about rod diameters of 200 millimeters (8") and up. Many of these rods were induction-hardened. And a lot of them would come to us "bent" as defined above.
At the time, the replacement cost of the smallest of these rods was around $10,000. So if we had refused to straighten these rods, we would have made a heap of money - right up until the point when our customers woke up and we lost all this work to our competitors.
Back then, we gave a 6,000 hour warranty on all our rebuilds. And the expectation of any rod we straightened to our satisfaction, was that we wouldn't see it again for at least 10,000 hours.
Notice too, I said many of these rods were induction hardened. In the interest of full disclosure, I have heard third or fourth-hand accounts of the induction-hardened layer violently shattering while straightening was been attempted. In my direct experience of straightening induction-hardened rods, I've never known this to happen. Nor have I ever heard a first or second-hand account of this happening from a reliable source.
My suspicion about this is, when it has occurred, the rod being straightened was bent like your elbow, rather than "bent" as I have defined it above. Either way, the benefit of doubt, and therefore the possibility of this happening, must be conceded. You have been warned.
#HydraulicCylinderRod #CylinderRodBent #hydraulicCylinderstuck
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These craftsman have amazing truck manufacturing and crafting skills.
Todos los comentarios (21)
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We have safety glasses, shoes, hoists, chains, shops with all the equipment, highly trained and paid people, but we do one thing exactly the same as these guys. One guy does all the work and everyone watches
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Хром повредили, поверхность поцарапана, масло будет течь из-под сальников. Цилиндр уже не даст расчётной мощности. Ещё и сделали отжиг штока. Теперь нужно делать закалку и отпуск, а они, скорее всего, даже не знают из какого сплава сделан этот шток и какой режим закалки делать. Судя по всему этот шток гнулся и выпрямлялся уже не в первый раз, если его так сильно погнуло… Качественный ремонт в таких условиях не сделать, если там только нет чудо-мастеров, которые обладают необходимым парком оборудования для такого ремонта (судя по тому, как доставали шток из гидроцилиндра, с мастерами и оборудованием там все не совсем хорошо).
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This video should be seen in all workshops around the world. What NOT to do at work.
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People making fun of these guys probably never even changed a car tire. They have minimal resources and got the job done, you think if they can afford a new rod they wouldn't have thought of that?
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A series problem is that when a rod is bent like that, it has crossed it's elastic limit at that specific zone and it can no longer withstand heavy loads intended for it. And It will get even worse. Just straightening it up won't solve the problem.
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I love the OSHA approved safety sandals
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This shows that adjusting the pressure relief valve can save you a lot of work on unnecessary damages of hydraulic equipement :)
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Will be amazed if it worked .I used to work making hydraulic rams and the tolerances are around 10000th of an inch....
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Best episode of Cutting Edge Engineering ever.
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I don’t know where to start. Annealing the rod in the fire will destroy its strength. The chrome platting is damaged by the bend and will flake off in short order. In the straightening process they used a flat rough metal plate, nothing to say the v block on the bottom, there is more scars on that rod than you can imagine. This hydraulic cylinder is going to leak and the first hard push and the rod is going to bow due to being annealed. As far as the rod being straight, well, I’ll leave that up to you.
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Respect to these men working with whatever they have available.
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Metal has memory. Once the grain flow has been disrupted, that’s forever. Incredible repair with available resources.
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Immediate opening for heavy equipment mechanic, must have your own hammer and rock. Shoes preferred but not required.
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Working on heavy equipment with flip flops an saddles on these men are brave.
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Is anyone else wondering why they just didn't pressurize the cylinder and let hydraulics do the work ?? Just stand to the side.
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Id love to see a reaction to this from Kurtis at Cutting Edge
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That chrome plating is pretty important, looks like they did a number on it. Not to mention ruining any prior heat treatment by putting the part in fire. I’m sure it will still work, just not very well or for very long.
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winch, steel cable, chain, car, and somewhere in the world an unnamed safety inspector is getting a stroke but this guys did an excellent job with minimal resources and maximum effort, respect !
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I've straightened rams before, when a new one wasn't available quickly enough and they've been run every day for years, cancelled the order for a new one. Seals will tolerate a little bit of wobble, maybe not as long as a dead straight rod but plenty good enough for these guys. Not everybody can afford to just buy a new one. I've done some very sketchy repairs to get me going, then bought the new part but kept it until the repair fails and incredibly, it never fails.
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I see so many comments with all kinds of technical concerns but I'm just here amazed at how these guys just get things done with pretty basic tools and sweat. Working on the dirt too. I'll even bet that isn't the first time that rod was bent lol.
