Testing hydraulic cylinders

I have a pair of hydraulic cylinders, they are very large, I would say 200-250 lbs each and about 3.5' long and 10" thick. They came from
50,000 (fifty thousand) pound rated rough terrain forklifts.
Unlike the smaller cylinder that I have, I cannot move their rods by hand. So, I want to test that they are not stuck, in the following way.
I think that their openings are 1/2" NPT. I could buy a 1/2" to 1/4" NPT adaptor and use compressed air (gently) to move them in one or another direction. Does it make sense?
thanks
i
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Ignoramus32469 wrote:

DO NOT!! use air! The reasons for that statement are too many to list. Let's just start with what happens when the air pressure overcomes the 'friction' of the cylinder. Can you say zero to 1000 fpm in .001 seconds? Thought you could.
Ken.
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I suggest to do it. But only to iggy. This would solve some anoyances.
Nick
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Yes, I see the issue. Now, if the other plug on this double acting cylinder is plugged, would that make any difference? Just tryin' to clarify...
i
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Certainly. If the cylinders are "good", the ram will move a little, then move almost back home when pressure is relieved.
If the piston seals are bad, the ram may not move at all, as pressure equalizes on both sides of the piston. If the rod seals are bad (and the piston good) the ram may move slowly toward the extended position, and stay that way when pressure is removed.
Still... air's not a good test medium for anything but little 1" stroke clamp cylinders.
Lloyd
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wrote:

Well, I am not thinking of releasing a big blast of 140 PSI compressed air into those monsters.
I was thinking of something supposedly safer, plug one end with a steel plug, and sllowly let air into another end, while safely standing away while the cylinder lies on a blanket. That sort of thing. I do not think that it will launch into the stratosphere, this way.
i
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It depends on what ya doin . If you're a Luddite college proff or a high school teacher .....
DONT use air , nor learn anything about hydraulics just stand back and shout OSHA manuals ...
Or ya cud read the first 13 pages of a harbor fright tool manual !
You could even apply for a govt job !
Fortunately these natures "competition " drop outs will not live in the USA in the near future .
All jobs will be GONE . There will be no factories , no employment agencies , no plumbers , no electricians no doctors , no nurses , no police , no lawyers , no govt , no OSHA , no poor , no 18 wheelers ......
The only people who will live in America are rich and clever and skilled in 5 different proffesions including business .
So if you want your kids to live in America , you best train them NOW . no more "can't do" and especially never use the word NO . They will need to develope a reputation just to buy groceries and pay the electric bill , lose repute in 1 day , they will pull the plug and the grocer will refuse to sell you groceries .
See what happens when you tossed your gov't !! Freedom means every person competes , every day , dont slip up or its deportation to Honduras .
Compete , learn , produce , no complaints , no excuses , no college diplomas , no English majors .... If you can do this , you may be in the competition to live FREE in the New America . Humans have another 100,000 years on this earth ...
There will be a replacement for the English language . It will be more GUI graphical . Verbs and punctuation will start sentences if its in text .
If you fail with too much air in your cylinder , how much do you have to fail to cause a problem ? See ! It is really easy if you "compete" and "figure" ...
Lloyd E. Sponenburgh wrote:

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for a video of test of these cylinders with compressed air, see
http://yabe.algebra.com/~ichudov/misc/ebay/Caterpillar-988B-Hydraulic-Cylinder/divx.Caterpillar-988B-Hydraulic-Cylinder-0001.avi
http://yabe.algebra.com/~ichudov/misc/ebay/Caterpillar-988B-Hydraulic-Cylinder/divx.Caterpillar-988B-Hydraulic-Cylinder-0002.avi
i

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<http://tinyurl.com/yk7yjx
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Dan

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Sounds like you speak from experience...hope it didn't hurt too much.
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Tom Gardner wrote:

As Fearless Fosdick would say "It's only a flesh wound".
Actually it was a disc brake cylinder (just a little shot of shop air will get it out). The shock wave when the piston hit the caliper numbed my hand for a bit; that plus the thought of what 'could' have happened convinced me that it was not a good idea and will not be repeated.
Ken.
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I still do it that way. Put a piece of wood in there to keep it from traveling too far, and toss a shop rag over the whole thing to keep from getting sprayed with residual brake fluid. Oh, and I still do go easy on the air, as for sure the piston or other parts can get damaged too. I've blown the rag off one time on a sticky piston, but the wood stopped it from reaching higher velocities. I normally try to get it to come almost to the end of the hole, right where the boot usually swells up (by the way, I use air to swell out the boot around the piston so I can get it back in the hole, too!) and it stops there. I don't do it often enough to be really good at it, though. There are hazards associated with everything we do in life. We manage to survive in a non-boring manner by mitigating the risks to an acceptable level.
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Carl McIver wrote:

Agreed - and I would probably use air in this situation again if the need came up. At least now I am older and (hopefully) wiser and can forsee possible hazards in any given process. I did not mean to start a "Mr. Safety" thread but I had an instant vision of our bud ig dumping 150 pounds of air in one of those monster cylinders, Chances are that nothing bad would have happened but................ Maybe sometime I will tell the story of how I discovered that an ordinary wood stove can function as a cannon.
Ken.
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Tell it!!!
As for the cylinders, I tested both and nothing bad happened, their rods moved smoothly, though a couple of small jerks occurred once or twice. I let air in only very carefully. Assuming 8" bore, at 140 PSI the cylinder would develop 7,033 pounds of force!!!
I did not try to stand in the way of the rod or on the opposite side of it. Just stood to the side and let air in a little by little.
The threaded openings were not actually 1/2" NPT, as I thought, close to it but not exactly. The result of that was that air was bleeding around the threads, which also helped avoid dangerous pressure buildup.
I think that testing an unloaded cyinder is different from load situations like a log splitter, where using air would lead to disastrous results.
At 2,000 PSI, these cylinders would develop approximately 100,000 lbs of pressure.
i
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Ignoramus16855 wrote:

OK ig - just for you (and anyone else who may get a giggle or a lesson out of it).
How to turn a wood stove into a cannon or How to wake up the neighbours or How to rattle windows for miles around. or (the 'now' version) - "Honestly officer, I am not a terrorist".
Don't try this at home kids!
I used to build these wood stoves (for a picture go to http://rainforest.htmlplanet.com/ ). After all was welded up and ground down the next step was to build a fire in them to burn off the production oils in preparation for painting. The procedure was simple: Set the stove up outside the shop on a convenient flat rock, attach one length of smoke pipe to it and build a roaring fire inside.
The design of the stove made this rather easy. A few pieces of fine kindling was placed in the bottom of the stove then shove a few strips of newspaper into the air intake. After lighting the paper the intake turned into a blowtorch, easily igliting the kindlling and in turn igniting a few sticks of firewood laid on top of said kindling. As I said this is (normally ) an easy task and in less time than it takes to write about it the stove is burning briskly. At least that was the plan.
On this particular day the load of kindling was somewhat damp and refused, after a few attempts, to properly ignite.
Bummer. T'was a beautiful summer day. The sun was shining and the birds were singing.
Well "hell" says I.
Spying a convenient container of chainsaw gas (my favorite industrial juice) I formulated a plan. Using my inate sense of caution I first made sure that there were no sparks or embers still smouldering in the stove - gotta be cautious!
A quick splash of the fuel mix and a re-load of some newsprint into the air intake.
So far so good.
In hindsight (always 20/20 ) I should have noted that the stove was 'quite' warm from the first attempt to light it.
Did I say "the birds were singing"? Well not for long!
Lighting the paper I took a giant step back.
Good thing I did as it it took no small period of time to regain my hearing from what happened next.
More or less instantly.
BLAM!!!!!!!!!!!!
Now I am not the worlds best welder (weldor to those who are retentive about this) but I have to say that nothing I have 'glued' together with hot molten metal has ever come apart under stress - and this was 'stress' of the first order! The stove did not come apart.
Collecting my senses I turned to look at the stove. The lid was missing.
Looking up I found it - an estimated 300 feet in the air - on its way down. That lid weighed in on the fat side of five pounds. That means that I shot a five pound-plus projectile over 300 feet straight up out of what was, effectively, a 3/4 inch long barrel using not more than two ounces of gasoline. The math gurus are invited to have a field day with this info.
The lid landed harmlessly a few feet north of the stove.
In answer to my neighbour's questions I invented an explanation - I was 'proofing' the stove (fortunately I did not have to answer any dumb 'official' questions due to the 'bush' location of my shop).
Sigh: Life is a learning curve, sometimes steep, sometimes sudden, sometimes terminal but always interesting. This should never stop us from having fun.
Regards. Ken.
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A VERY impressive story. Thank you for sharing.
i
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^^^^^^^^^^^^^^^^ I knew an elevator repairman who used a small pump in a pistol drill. It was slow, but he could raise an elevator with it.
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Hey Leo,
Who is that guy? Where's he from??
Brian Lawson, Local Representative, Dover Elevator (retired)
XXXXXXXXXXXXXXXXXX
On Fri, 27 Oct 2006 05:04:14 GMT, "Leo Lichtman"

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If the cylinders ARE _just a little_ stuck, you're in for an interesting ride! The pressure will build... and build... and.....
WHAMMMO! The 100lb rod will come slamming out at a velocity that will likely clear the room.
No... don't.
Use oil, supply it with a low-volume pump, regulated to a low pressure.
LLoyd
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Hey Iggy,
Unless you have access to some sort of a pump, or a "Porta-Power" pump, just fill a plain old grease gun with cheap oil, pour some of the cheap oil in the cylinder port, attach a reducer fitting to it that fits the grease gun and pump away. I'm told that will develop some 1500 PSI.
Brain Lawson, Bothwell, Ontario.
XXXXXXXXXX
On Fri, 27 Oct 2006 03:44:54 +0000 (UTC), Ignoramus32469

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