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Thread: Here's a bit of Hydraulic info.

  1. #11
    My post count is not going up either. I will check this thread tomorrow to see if the counts go up, perhaps it recalculates once a day.
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  2. #12
    Senior Member frijoli's Avatar
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    No need to shoot in the dark hamstn. We can work with what you got, or we can work with what you want and go that way.

    There is going to be a trade off. If you get a smaller pump, you can go less HP, however, your cylinder will also move slower.

    How fast do you want the cylinder to move is the best place to start. Inches per second is what I like because it's reasonably easy to estimate.

    Also, you're going to need a pressure relief valve before we go any further! i don't want you to break anything.

    Clay

  3. #13
    But dam Clay you made four post or so and still stuck at 85....at least we even. I refreshed and mine went up one after I removed the quote....no biggy

    This pump will move the cylinder way to fast, as it was on the combine with two bigger cylinders and all other hydraulics. I am going to say to be safe I would like at least .25"/second but could live with .5-.75". I can have some control over the speed with the greasson(sp) valve. I will see if I can come up with a relief valve.
    Last edited by Hamstn; 01-03-2010 at 09:01 PM.

  4. #14
    Senior Member frijoli's Avatar
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    I'll be okay.

  5. #15
    Your count went from 83 to 87, perhaps there is a polling time before posts are incremented. I'm only guessing but the counts are going up eventually. Keep an eye on the posts that don't go up and see if they increment later.
    Units owned Longevity PROmts 200

    Force Cut LP80 plasma cutter
    Longevity auto dark welding helmet

    Atlas 10x36" lathe
    Craftsman 5HP 30 Gal compressor
    Home made CNC router/plasma/hot wire foam cutting, 3D printing table powered by Longevity Force Cut LP80
    Home built aluminum foundry, HF 4x6 bandsaw

  6. #16
    Senior Member frijoli's Avatar
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    I guess I'm talking to fast!.

    Night folks. See you in, my, AM

  7. #17
    Senior Member frijoli's Avatar
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    Quote Originally Posted by Hamstn View Post
    But dam Clay you made four post or so and still stuck at 85....at least we even. I refreshed and mine went up one after I removed the quote....no biggy

    This pump will move the cylinder way to fast, as it was on the combine with two bigger cylinders and all other hydraulics. I am going to say to be safe I would like at least .25"/second but could live with .5-.75". I can have some control over the speed with the greasson(sp) valve. I will see if I can come up with a relief valve.
    You will defintiley need a relief valve if the pump is fixed volume. A gear pump and most Vane pumps are. If this is from an existing system, there will be a relief vale somewhere on it. Some times mounted in the Greeson body.

    At 1500 PSI you'll need a BIG bore to get to 40 tons. I don't know what your Cessna is rated at, but it's probably 1500-2000.

    1 Get a bigger cylinder. 8" bore to get close to 40 tons.
    2 Get a higher pressure pump or a High/low pump which is an excellent idea for presses because they have speed and pressure.
    3 Get a pressure compensated pump which has maximum flow at low pressure and maximum pressure at low flow. These tend to be the most expensive.

    A pressure relief valve is needed as a safety precaution for all hydraulic systems, and absolutely necessary for fixed volume pumps.

    more to follow...................

  8. #18
    I will look for the relief valve. I have a multi tap valve with adjustable relief but do not want to use it if I have to cause to is a bit big.

    I also know that there is a flow control valve that I can use.

    I don't have a really big bore cylinder around here that I know of. I should have another mate to the one I want to use if I can just locate it. I also have two other matching cylinders but they are a bit longer then I was wanting. The pro of them is they are double acting while the ones I want to use is single and would have to use springs or something to retract unless I tear them apart and tap in another connector.

    After looking at pumps this morning my real problem right now I think is getting enough HP to run it. I was going reduced belt drive with a 1750 motor.

  9. #19
    Senior Member frijoli's Avatar
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    Quote Originally Posted by Hamstn View Post
    I will look for the relief valve. I have a multi tap valve with adjustable relief but do not want to use it if I have to cause to is a bit big.

    I also know that there is a flow control valve that I can use.

    I don't have a really big bore cylinder around here that I know of. I should have another mate to the one I want to use if I can just locate it. I also have two other matching cylinders but they are a bit longer then I was wanting. The pro of them is they are double acting while the ones I want to use is single and would have to use springs or something to retract unless I tear them apart and tap in another connector.

    After looking at pumps this morning my real problem right now I think is getting enough HP to run it. I was going reduced belt drive with a 1750 motor.
    What rpm is your pump rated, or what speed did you run it to get 12GPM?

    We know what tonnage you would like, how fast you would like your cylinders to move, so let's work that way.
    Do you know at what pressure your cylinders are rated? Most mobile hydraulic cylinders are rated under 2000psi working pressure?

    if we have 2000 psi available we need 40 square inches to hit 40 tons, right? which ends up being a cylinder bore of about 7 1/8" which is an odd one. But we'll use it for now.

    to figure speed of the cylinder, we need to calculate the volume of 1 inch of travel. so 40"sq x 1 equals???? 40cubic inches cool huh?

    1 gallon is 231 cubic inches. 1 gpm per minute is 231cubic inches per minute. 231cubic inches divided by 40cubic inches = 5.775" travel per minute of your cylinder. We have a 12gpm pump so 12 * 5.775 = 69.3" per minute. Divide that by 60 seconds, and we have 1.15" second cylinder speed. So we're good there @ 12gpm.

    There is no way around this volume to force relationship. we need 40sq in. to get 40 tons at 2000psi. you can use 2 cylinders if you put a flow divider in the system. you would need two 5" bore cylinders to do it.

    Clay

    ---------- Post added at 08:00 PM ---------- Previous post was at 07:48 PM ----------

    Last edited by frijoli; 01-04-2010 at 06:02 PM.

  10. #20
    The pump on the combine was running at 2400rpm at full throttle. I don't have a clue what rpm was used to get the 12gal/min rating.

    I rounded up two 4" cylinders today. They look to be in good condition other then the screw on cleves was worn on one and 1" broke off the other. These are cheaper cylinders so not over 2000psi.

    Didn't get time to track down the relief valve, but I did get the motor and pump set up with about a 3:1 reduction and built 500lbs before the motor stalled. Not sure of HP but it is small and every thing is in metric. 4kw? So I need to get my brothers cataloge out and get a 5 or 6 hp. Beginning to wonder if this is going to be worth it. I also have tow other pumps. One is a vane pump but I think it is high volume to run motors. The other one I am unsure about other then it says gre-son. No other markings.

    I may have to settle with lower tonage. 1.15"/second sounds plenty fast, maybe to fast if you were trying to press a bearing or something but I do have a flow control valve.

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