Testing hydraulic cylinders

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.

^^^^^^^^^^^^^^^^ 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.

I suggest to do it. But only to iggy. This would solve some anoyances.

Nick

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

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

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

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

Sounds like you speak from experience...hope it didn't hurt too much.

>

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.

Hey Leo,

Who is that guy? Where's he from??

Brian Lawson, Local Representative, Dover Elevator (retired)

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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.

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That still over-simplifies the picture, and makes for a potentially dangerous air-propelled accident.

One must bleed the air out of the system to prevent a sudden release of energy.

LLoyd

Brian, that would mean buying four gallons of oil to fill that sucker. (thinking big here!) This is not a typical hydraulic cylinder. It weighs more than I do.

i

Ok... $32 for a 5-gallon pail; recoverable, re-usable, useful for other tasks.

Even if you only intended to re-sell them, it doesn't sound like much of a chip off the profits.

LLoyd

Yea... but... where to store it...

Anyway, I have an idea. I will fill air hoses with air, then close off the compressor, and try to apply only that amount. It is not that much

-- whatever fits into 100 ft of 3/8" ID hose. That's 164 cubic centimeters of compressed air, and only about 10 liters of uncompressed air (2.6 gal). It could not do as much damage and would likely move the cylinder a little.

The procedure will be thus:

1) Attach air hose to cylinder input 2) Close the valve near cylinder 3) Open air valve near compressor, count to 3 4) Close air valve near compressor 5) open air valve near cylinder i

Can I assume that these cylinders are single acting as in pressure to extend, load is what retracts?

Wes S

Sorry Wes, I forgot to add, they are double acting. Pressure on one side == extend, on another it means retract.

i

I will try to connect them to a Delavad 4 way hydraulic globe valve and less with low pressure compressed air a little... I will restrict air out...

pic is here

maybe I will shoot some fun video

i