Hydraulic cylinder use
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    Default Hydraulic cylinder use

    Is this type of cylinder usable in a two way configuration~ or single action only~ as in "gravity return" only? They are for raising the boom on a crane and I want to use them for another application that would have pressure on the return side.

    0917132119.jpg 0917132118.jpg

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    Can't tell from the pictures, but: If it only has a welded drain tube coming out of the rod side, and not a JIC fitting boss, it's probably single acting. If the rod side is built as heavy as the blind side you can machine it for a fitting BUT it probably has a one-way piston seal (stack of v-packing) which you will also have to change. And, since the rod seal is probably only intended to handle return pressure you may have to change that as well. Otherwise, why not? The cylinder tube itself is uniform wall all the way.

    OTOH if it has a block at one end with two pressure hoses coming to it, it's double-acting and that welded tube is just a permanent design feature.

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    How much pressure?
    Test them....

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    Do you have a way to test the thickness of the steel tubing? UT?

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    I had UT done on a lot of parts I made for the Navy, but I didnt do it..sent it to a Testing Lab
    and from what I remember they prepare a sample of the material and drill very small holes in the
    sample so the UT screen shows those as defects... I think you need to look at the other end of the cyl
    and maybe take it apart to determine the wall thickness. Then determine the capability of
    this for your application.....

    or just use the old farmer method.... tap the cylinder with a hammer...LIGHT taps... ya know??

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    That's more complicated than I was thinking. But whatever works to get a thickness and then you can get an allowable working pressure.

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    Worth remember most crane boom lift cylinders will have a large diameter rod to cylinder bore, Excavator cylinders will generally have a smaller rod allowing for a larger anulus hence more retraction force from the same sized cylinder bore.

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    We have a 8" bore, ~48" stroke cylinder in a load frame that has a very similar steel return line and it is a two way cylinder, we run 3,000psi servohydraulic lines to it and have never had an issue with our application on it. At the top of the cylinder the line has a JIC fitting welded onto it.

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    Bailey will probably sell you a new cylinder cheaper than you can rig that one up.Hydraulic Cylinders | Bailey Hydraulics | Hydraulic Supplier

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    As posted elsewhere..

    This cylinder probably does not have proper gland seal setup, for pressure on that side of piston.

    All a crane boom cylinder like that needs, are good wiper seals to keep water out...

    Yes there is always a wiper, it is the non visible setup of V or U or W or O ring packings, backer rings etc.. that will cause problems..

    No need to install a pressure seal there, so one was not likely put in.. No available high pressure oil, to keep a pressure seal lubed properly.... is also a factor..

    So you will likely have a leaky mess, unless seal is set up different..

    I removed repaired reinstalled 2ea cylinder gland seals on a Hitachi excavator this summer.. (smaller cylinders diameter only ~ 6in)

    The torque required to break piston nuts loose ~10,600 ft lbs..

    The piston nut has to come off to replace gland seal...

    My labor cost was more than what a log splitter cylinder costs....

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    Those cylinders are double acting so go ahead and use them. If they were on some sort of crane there ain't no way in hell they aren't. The manifold tubes are for the retract side of the cylinder. I design these things for a living and use W-FLT for retract lines exactly the way those are done. Also, can't tell from the second pic, but it looks like there may be some type of port block for plumbing? If so, see if there are c'balance or p.o. check valves.

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    I looked it up on the net and this is from a Grove RT5xx series crane... at least that is what it resembles from the photo I found. More snooping reveals that it is a 9" diameter x 38" stroke and there are seal kits available on the net, too. Grove evidently used the same boom lift cylinder on multiple models of machine.

    It doesn't spell out what seals you get that may give some clue as to what I have.

    I am torn between two answers. R. Dan and ABarnsley.

    Mr. Barnsley.... if this was just single acting, why would there be oil on that side of the piston in the first place- to give the piston a little cushioning action?

    When they were removing it they ran a strap thru the pin hole and lifted it off the machine. It took a bit, but after it had hung that way about 20 seconds oil started flowing out the return line connection.... slowly, but it picked up after a bit- at least 2 gallons shot out of the hole. The lifting boom they were using was slow acting so they couldn't drop it quick enough to stem the flow of oil by setting it on the ground.

    I can understand it being single acting, but not why there would be oil on the retract side. If I was to use it double acting as is, with no work being done on the retract cycle... wonder if what seals are there would hold back a couple hundred pounds of pressure... whatever it takes to make that piston move?

    What I am probably going to do is hook the cylinder up to a power unit and pressurize the return leg and see what happens.... see how little pressure I can feed it and make it work... all the way retracted and see how it acts bottomed out.

    I called the fellas at "Baum Iron and Hydraulics" today and asked there expert about this, too. After I explained what I had, what it came off of and what it did... first thing he says is "that's a two way cylinder" and "in this day and age they don't use single acting cylinders for such things." Their words.

    As I get around to it, I will give it a test and resurrect the thread. For those of you who don't go there, I started this thread out on the Antique forum by accident....posted that and hoped for the moderator to move it, but haven't seen that happen yet. It needed to be over here.

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    Quote Originally Posted by JoeE. View Post
    I looked it up on the net and this is from a Grove RT5xx series crane... at least that is what it resembles from the photo I found. More snooping reveals that it is a 9" diameter x 38" stroke and there are seal kits available on the net, too. Grove evidently used the same boom lift cylinder on multiple models of machine.

    It doesn't spell out what seals you get that may give some clue as to what I have.

    I am torn between two answers. R. Dan and ABarnsley.

    Mr. Barnsley.... if this was just single acting, why would there be oil on that side of the piston in the first place- to give the piston a little cushioning action?
    To prevent corrosion, to keep things clean, to act as a heat sink, and to act as a reservoir.

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    Quote Originally Posted by R. Dan View Post
    and use W-FLT for retract lines exactly the way those are done. Also, can't tell from the second pic, but it looks like there may be some type of port block for plumbing? If so, see if there are c'balance or p.o. check valves.
    What is "W-FLT" ? And, yes, those blocks do have some sort of a check valve built in the bottom of the block....

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    Lotsa wild-ass guessing here from people who know no more about crane boom elevation cylinders than I know about flying the space shuttle, R Dan excluded.

    The cylinders are double acting. Both hose connections will be at the block near the base of the cylinder. There's a cartridge type holding valve screwed into the block too. With the holding valve, you could chop the hoses off with an axe and the cylinder will just sit there even if fully loaded. You can get seal kits for the holding valves if they're leaking. Due to the way the block is ported, you can't just take out the holding valve and use the cylinder without it.

    Most Grove boom cylinders also have a pilot line coming into the block that's set up such that you have to develop a certain amount of pressure on the rod side of the piston before the cylinder will begin to retract. IOW, it won't retract just by simply opening the return valve. This is done for two reasons. It controls the max retract speed of the cylinder, which controls the max rate at which you can lower the boom. It also keeps the cylinder from loping as the boom comes down. If the cylinder lopes (alternating fast slow fast slow motion), that's usually indicative of a broken spring within the holding valve assembly.

    Most of Grove's cylinders use Sirvon piston seals. They're used to minimize any stick-slip motion because the piston will move freely in the bore due to the fact that the seal is narrow and the preload is very low as compared to a loaded u-cup type seal. Downside is the sirvon ring is very delicate and you have to use extreme care in sliding it over the piston and into the groove. A seal kit for one of these cylinders, consisting of piston and rod seals, wear rings, etc, is probably upward of $200 now from Hercules hydraulics, or twice that from Grove.

    If these cylinders have good bores, pistons, and rods they can be far more valuable to someone who's looking for a spare than they'd be for any repurposed use. Last time I priced a Grove boom cylinder was 20 yrs ago. At that time, a 12" bore x 60" stroke boom cylinder was right at $26,000, and would likely be on the north side of $40K today with a lead time of a few weeks. There's a good used market for Grove parts.

    Unlike some of the excavator cylinders, these are pretty easy to get apart. Typical retainer for the rod seal gland is a split ring with an external thread that screws into the end of the cylinder and then locked in place with a tapered pipe plug that screws into the ring at the split to expand the ring, plus a couple capscrews that pass thru the ring and thread into the upper part of the seal gland. The seal gland and the piston are both aluminum in every one of these cylinders I've ever worked on. The piston retaining nut varies depending on the particular cylinder. Some aree just snugged up and retained by a setscrew with a nylon plug while others have a hex nut upward of 6" across the flats. Those require a box wrench burned from about 1" plate so the wrench handle can be smacked with a hammer to loosen or tighten, unless you already happen to have a 6" combination wrench laying around

    The rod is normally hollow. If so, there's a small screw with a sealing washer screwed into the rod near the eye. This screw is removed to bleed air from the rod because cycling the cylinder won't remove this air.

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    Quote Originally Posted by JoeE. View Post
    What is "W-FLT" ? And, yes, those blocks do have some sort of a check valve built in the bottom of the block....
    Hydraulic fluid line tubing, soft annealed.

    Joe, your cylinders are double acting. That's why there was oil on the retract side. When I design a single acting cylinder, I put a felt mop ring on the piston to keep the outside end lubricated, but unless it's a single acting displacement style cylinder (oil through or around the piston), there isn't going to be much oil on that side. If it was a single acting displacement style cylinder, you would not have those manifold tubes as they would have no purpose. The valves are either counterbalance valves, or at the very least, a pilot operated check valve.

    These other guys can speculate all they want. This is what I do and have done for 25 years.

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    Munchr and Dan.... I appreciate the feedback.

    They cost that much ! That's hard to believe.

    Well, if that's bad, what is worse is that the big cylinder that extends the length of the boom is going to be cut up- it's still in place and this whole machine is going under the torch here pretty quick.

    I was gonna have them get me that cylinder, but it's inside the boom section still and I didn't want to fool with it...and it's way to long for me to find a use for.

    It does seem like a waste to use these for a something like a logsplitter.

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    Metlmuncher nailed it. This is for overhead lifting- every safety feature known to man is there. A displacement cylinder would lift the boom- but a failure would let it drop like a stone. A single acting cylinder, a little slower. So a double acting (even if only one side will ever do any work) and a counterbalance valve means , as metlmuncher said, you could chop off the hoses and probably not see visible movement.

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    I really wish my line of work dealt with more hydraulics, they're much cooler than pneumatics.

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    Well, I got around to building that log splitter, using one of those cylinders. Measuring, they've got 36" of travel and they are 8" bore. 3" rod diameter. The H beam is 12", 5/8" thick members.

    55.jpg

    After I got it mounted, I connected hydraulic lines from my current log splitter control valve to this cylinder. My current machine's hydraulic pump doesn't have the volume needed to cycle the cylinder fast enough... it took a minute and 45 seconds to go from retracted to fully extended!

    I removed the "check valve" from the manifold block on the cylinder, so there is no restriction in there anymore.

    5.jpg

    I bought a 30gpm capacity control valve. Haven't bought a pump yet because I'm not sure what I'll need.

    The cylinder volume is around 7½ gallons extended.

    It would be nice to have around a 30 second "extend" time... or less. 30 seconds is a long time to stand there pulling on a handle. I built this thing to enable me to big, large diameter pieces that nobody else wants. My other splitter could handle the pieces that result after first running them through this monster.

    What's tripping me up is that I'm unsure how many gpm of hydraulic fluid it's possible to pump through 1/2" hydraulic hoses and fitting before it causes problems. I suppose I could run 5/8" or 3/4" hose, but it'd still be throttled down when it got to the fittings.

    I found a number of charts on fluid velocity as it compares to PSI and velocity and hose diameter, but I'm not mathematically inclined enough to work any of that out.

    I'm just afraid I may have outsmarted myself using this particular type of cylinder because maybe it wasn't designed to cycle this quickly... it didn't need large volume of oil because it wasn't intended to extend very quickly...


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