Thoughts on the design of a ridiculously oversized hydraulic ram setup

[calweld]

I think the issue here is getting a hint of the design pressure that the cylinder might have been made for. Prior to the early 1980's most hydrualic systems were faiarly low pressure affairs (less than 2000 PSI) then the Japanese excavators hit with 3 ot 5000 PSI" systems.

It is kind of important not to use a high pressure pump on a low pressure cylinder. Likewise the hoses for the high pressure systems are different as well.

It's easy enough to tell if you take the cylinder apart. Anyway, a cylinder this big there's no reason to use a high pressure pump for the uses specified.

A failed hydrualic system is not pretty

There is a particular danger in using pipe for plumbing. A few years ago a guy I know was adjusting an implement while an operator was in the tractor controlling the hydraulics. Just as the man put his hand on the hydraulic line (pipe) to jump over the implement, it split and injected hydraulic fluid into his hand. As I understand it, it was touch and go for a while whether or not they were going to be able to save his hand, they ended up not amputating.

Anymore, the only pipe I use on hydraulics (aside of steel hydraulic tubing) is schedule 80, with slip-on and welded ends (no threads cut into the pipe). These ends are commercially available, usually machined for o-ring boss type fittings.

[Portable Welder]

It sounds like alot of work and alot of money for something that might be a little impractible, In the long run you may be farther ahead selling the cylinder and buying a tubing bender and a log splitter that already have a proven desighn.
I'm saying this because over the years I have had guys bring me projects to work on that never flew.
Maybe you have more intended uses for this hydraulic set up, If so good luck on this project, the nice thing about projects like this is you have the potential to learn alot about hydraulics.

[Rvannatta]

It's easy enough to tell if you take the cylinder apart. Anyway, a cylinder this big there's no reason to use a high pressure pump for the uses specified.



There is a particular danger in using pipe for plumbing. A few years ago a guy I know was adjusting an implement while an operator was in the tractor controlling the hydraulics. Just as the man put his hand on the hydraulic line (pipe) to jump over the implement, it split and injected hydraulic fluid into his hand. As I understand it, it was touch and go for a while whether or not they were going to be able to save his hand, they ended up not amputating.

Anymore, the only pipe I use on hydraulics (aside of steel hydraulic tubing) is schedule 80, with slip-on and welded ends (no threads cut into the pipe). These ends are commercially available, usually machined for o-ring boss type fittings.

what would you see different inside the cylinder????

I've had both apart and didn't see obvious differences but then I probably didn't look for the right thing. I know some of the old low pressure ones can have very crude seals. Sometimes just piston rings, pump packing etc. but there are also low pressure cylinders with good polypaks in them as well.

Agreed you can usally get a clue looking the the plumbing, unless the last guy used high pressure plumbing with a low pressure system, but I agree that the presence of pipe threads is a good sign of low pressure plumbing. Ditto for the 'user assembled' JIC fittings. We always get press assembled hoses for the high pressure systems (with high pressure hose). The flange / o-ring fittings are common for this, but some equipment uses JIC.

Those 1" and larger high pressure hoses are real money being metric, they price them out by the centimeter.

We have some hydrostatic drive logskidders that use Poclain wobble plate motors and why hydrualics will do is amazing but you need to respect them.
The wobble plate is an interesting design. The have a plate in them sort of like a cupcake paper flattened out some and little pistons with rollers on them press on the 'angles' of the folds forcing the plate to turn.

the motors are '2 speed' in that in high speed the valving is changed to shut off half the pistons forcing all the oil through the other half thus increasing the speed. No gear redutions are necessary and the wheels of the skidder are bolted directly to the motor. There is an external band brake released by the same oil p;ressure that drives the motor so when the oil pressure goes away the brake sets.

[calweld]

what would you see different inside the cylinder????

If the packing/seals are updated and the cylinder wall is heavy enough, it could probably now be used as a high pressure cylinder.

Many high-pressure systems were plumbed with pipe, you could often get away with it so people did it, so you can't always tell just looking at it. You have to evaluate the whole system, generally with experience you can tell, but sometimes you just have to plumb in a pressure gauge to find out for sure.

Part of the reason for the confusion on pressures and the accidents that result are because the original hydraulic systems that were built years ago were actually 800 psi systems, most things today run on 2000 psi systems, this is what most ag and industrial equipment use, and then you have the high pressure systems like on the excavators you cited.

Most of the common crimped on fitting hoses are two wire hoses, in the common 1/2" and 3/4" and 1" sizes they are rated safely for the 2000 psi systems (with a healthy safety margin). For the higher pressure systems, you need to go to the 4-wire hoses, which are considerably more expensive and harder to find, as most places that make hose don't stock this. Oftentimes the two wire hoses end up on systems that run higher pressures than is safe for the hose, simply because the person buying the hose either didn't know any better or just couldn't find the right hose in a hurry. It works for a while, but at some point you could expect it to blow again.

[Coalsmoke]

Alha, ask the guy if he knows what the cylinder came out of originally? If it has no tag, it may be off of heavy equipmnet, which would be good for you, because that would mean that the cylinders ends are cushioned. Most presses (and other fixed stroke applications) cheap out and do not use cushioned cylinders to keep costs down. If this cylinder is not cusioned, you will not want to bottom and / or top out the cylinder. Take and post a picture of the cap where the ram goes into the cylinder body with attention to the primary (front) seal area. Make sure it is in focus.

[alha]

Guys, I get the impression from talking to him that he purchased it new. He is an engineer who was designing a prototype of some machine, haven't gotten all the details of it yet, but sounded pretty interesting(something to do with NASA, I believe he said), he was going to send pics eventually. Here are the specs from the auction:

Hydraulic Industrial Cylinder - 70 Ton Capacity - 8" Dia. - 5' Long.

Piece No. P151198-0

Model: MS2-HH

Bore 8 Str 45

WP3000 PSI

Manufactured by WABCO - Westinghouse Air Brake Company; Fluid Power Division; Lexington, Kentucky USA.

This very large unit was sparsely used 15 years for research and is in very good condition.

The Cylinder weighs about 800 lbs.

The unit is 81"L X 15"W X 12"H; with a 3" diameter pin with a 1" diameter hole.


I did some research on WABCO, they were bought out by American Standard in the 60's but in the late 80's, apparently due to some financial pressure resulting from a hostile takeover attempt they thwarted, they needed to divest this division, looks like they sold it to Bosch Rexroth Corp. I'm going to be contacting them about it, to try and find the mfg specs, and also possibly a rebuild kit for down the road.

I'll get a pic posted as soon as the garage gets a bit more organized, but that won't be for a month or so, once the shop is done and the stuff is moved back there. Been a long time coming...

In the mean time, is there a way to know what it is I would be looking for, is the end of it a different shape that would signify that it is cushioned? I also got a Bunch of steel reinforced braided and other lines with it, he said they were pretty expensive, and to just shoot him a check for whatever I thought they were worth. He's a very nice guy, I think in his late 70's, but talking to him I would swear he isn't a day over 60.

One last thing, I can see the end without the rod, the hole is about 1/2-3/4" for the input line, which is in the middle of a plug which is about 1 1/2-2", I presume that could be removed and that big of a line could be installed. The lines I have all have fittings if I remember correctly of less than an inch, I'm pretty sure.

[Fishy Jim]

It's rated for 3000psi. You'll be fine as long as you use the right hose and fittings.

I wish I could tell you a good place to go for hydraulics here in the Metro, but I have yet to find one that's all that reasonable on price or easy to deal with. There are a bunch around though. Maybe check the place on University down the street from Axeman. Axeman in Hopkins has a big bin of hydraulic line ends too. You might find something useful there.

There's a guy in Princeton on Craigslist selling a cylinder, pump, and motor with 4 way valve for $250 (used). All he knows about it is that it's a 2HP 120v motor.

[Coalsmoke]

alha, don't bother with the rebuild kit for the amount use it will probably see. If the cylinder leaks or weeps then do a rebuild.

only two ways to find out if it is cushioned: open it up and visually inspect or pick up phone and call manufacturer (I'll let you judge which is easier)

3000psi Wp is good, and most power packs don't put out much more than that, just don't use a 'jack pack' (good for about 8500psi).

[alha]

Since I bought pretty much his entire setup, I think I should be fine in terms of hoses, valves, etc. Got a 2x2x3' box of them from him, the ones he had used, which were working fine when he decommissioned it. I will also be using his motor/pump combo, so my guess is that I shouldn't have any issues, other than it possibly may be a wee bit slower that it could be if I had a higher GPM pump.

So....

Now for the design of how to mount this thing. Box beam or I beam, or something else? The spread between the feet from outside to outside I remember measuring at about 12-13 inches, so whatever I use would have to be at least that wide. Then there's the attachment piece, where I would mount the different accessories, would a slot/tab or a box beam sliding into a bigger one be better? This is really where I am at a loss in terms of what would be the best design.

[Fishy Jim]

You have a copy of Machinery's Handbook right?

You can calculate the strength needed based on the formula's in their charts. 140,000lbs is putting you into exotic materials, or some really thick stock with whatever you choose to use.

Lack of speed with this one is a very good thing IMO. You don't want that sucker launching whatever it breaks at a high rate of speed.

[Sberry]

I wanna play poker with alha, he is going to throw good money after bad, I tend to think you will learn a lesson here other than the fine technical info. Aint nuthin that a 150$ porto power wont do here. But dont feel bad I spend 3 0r 400 hundred last week I could have bought for 75 and been done in 30 mins,,, hahahaah But I can see how this was a "good deal" and hard to pass up. My neighbor stops in telling me what a good deal a coupole cyls for sale are, what you could build with them and I understand if you really needed one that big it would be one thing but as a practical matter the amount of uses you could dream up for something like that would be rather limited in a hobby shop. If you are a married man I would have liked to learn from the master as you tried to pass this gem past the wife. Did you suggest there would be a long list of "honey do's" you could surely do with it? You got to excuse me, its late after midnight and I just had a picture of a couple a buds on Sat afternoon having a couple brewskies trying to fig out how to get this monster out of the Ranger and into the garage while 'splainin" the highlights to the Mrs.

[Coalsmoke]

Cary, that's pretty funny. You know, the only use I would have it would be as a gigantic pneumatic forging hammer. The real problem here would be the compressor to run it. By my calcs, I'd need 230cfm at 80psi.

[Rvannatta]

Part of the reason for the confusion on pressures and the accidents that result are because the original hydraulic systems that were built years ago were actually 800 psi systems, most things today run on 2000 psi systems, this is what most ag and industrial equipment use, and then you have the high pressure systems like on the excavators you cited.

Most of the common crimped on fitting hoses are two wire hoses, in the common 1/2" and 3/4" and 1" sizes they are rated safely for the 2000 psi systems (with a healthy safety margin). For the higher pressure systems, you need to go to the 4-wire hoses, which are considerably more expensive and harder to find, as most places that make hose don't stock this. Oftentimes the two wire hoses end up on systems that run higher pressures than is safe for the hose, simply because the person buying the hose either didn't know any better or just couldn't find the right hose in a hurry. It works for a while, but at some point you could expect it to blow again.

Yes, I"ve seen the really low pressure systems. Some with single braid hose.

We get our hoses made up at a pretty serious hydraulic supply house with a lot of inventory and a lot of knoweldge. The have about 4 guys working in their hydraulic shop that do nothing but make up hoses. They have 2 braid hose, 4 braid hose, suction hose, High Temp hose. and a few others.

For example if you are running oil from your Allison transmission to the transmission cooler--- the pressure isn't high---but the Temperature is.

The newer hoses will have the pressure rating of the hose on the label.

[calweld]

Alha, ask the guy if he knows what the cylinder came out of originally? If it has no tag, it may be off of heavy equipmnet, which would be good for you, because that would mean that the cylinders ends are cushioned. Most presses (and other fixed stroke applications) cheap out and do not use cushioned cylinders to keep costs down. If this cylinder is not cusioned, you will not want to bottom and / or top out the cylinder. Take and post a picture of the cap where the ram goes into the cylinder body with attention to the primary (front) seal area. Make sure it is in focus.

I very rarely see a tag on any cylinder, if there is one it's a stick-on label that soon falls off.

Cushioned???? How???? I've been in probably hundreds of cylinders of various types, I've never seen anything that I can remember being cushioned. Only cushioning systems I've seen had accumulators downstream to help take up the shock. Occasionally you will find sleeves inside the cylinder, but they are to limit the travel.

When engineering cylinders and applications, you always want the cylinder to bottom out and top out. If you can't get full stroke, you either rip the attachment points off the application or the ears off the cylinder or bend the shaft or something else serious like that. If you're adapting a cylinder to something and can't get full stroke, then you limit the stroke by placing sleeves on the shaft inside the cylinder or under the piston inside the cylinder. You can even shorten the barrel, and then the shaft if necessary. Cylinders are supposed to be able to bottom out in both directions, they are designed for that, even the cheap tie rod cylinders go full stroke no problem.

[Fishy Jim]

Some pneumatic cylinders have cushions. The Festo I have with a 15" stroke has adjustable ones that are set via a valve in the end caps. The 4" bore pancake cylinder I have doesn't and it's rated for nearly twice the psi.