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Hydraulic Help For A Dummy


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#16 UncleWillie ONLINE  

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Posted October 04, 2012 - 06:43 PM

Forget cost, forget what it will be attached to forget everything but the question I asked. Although I am starting to think that everyone is incapable of that. I guess I will have to find an answer elsewhere.

Edited by mybigwarwagon, October 04, 2012 - 06:53 PM.


#17 Guest_rat88_*

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Posted October 04, 2012 - 06:50 PM

The length of the arms will dictate what size cylinders are needed. The size of the cylinders will determine the size of the pump.
Pick a number between 1 and 100.
Sorry we could not help you.
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#18 UncleWillie OFFLINE  

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Posted October 04, 2012 - 07:05 PM

The length of the arms will dictate what size cylinders are needed. The size of the cylinders will determine the size of the pump.
Pick a number between 1 and 100.
Sorry we could not help you.


Finally an answer i can work with. Everything I was finding was on how hydraulics work and cyl leaking and cavitation and everythign but what I wanted to know. Is there a formula for determining the needed PSI for a specific cyl or the cyl needed for a particular PSI.

Say I stumbled into a 1200 PSI pump ( I didn't but say I did) how would I determine cyl size. Or if Santa drops a couple of 3 inch 4 foot long cyls down my chimney ( I don't have a chimney) what size pump would I need.

#19 Alc ONLINE  

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Posted October 04, 2012 - 07:05 PM

Here's a Brantly brochure with a 1000 lb loader , maybe you can copy all the size , pressures ,ect , Al

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#20 Guest_rat88_*

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Posted October 04, 2012 - 07:14 PM

Psi is not the answer. GPM is the big factor. A dinky hydro charge pump could produce 1200 psi but it would take all day to run one stroke on a log splitter. Length of the stroke (displacement) and required lift speed need to be accounted for.

#21 HowardsMF155 ONLINE  

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Posted October 04, 2012 - 07:17 PM

The basic calculation would be size of the rod in square inches x the system pressure. But you can't simply say, "I need a cylinder that can push 1000 lbs" because most hydraulic cylinders move a shorter distance than the final load does. Assuming that you attach your cylinder to the loader arm in such a way that one inch of cylinder travel equals 3 inches of bucket travel, I think you would need two cylinders that can push 3000 lbs. You can reach that figure by changing the rod diameter or by changing the system pressure. If you chose a reasonable 1000 psi as your system pressure, you need a minimum area of 3 square inches, and that works out to about two 1.5 inch rods. If you want bucket travel to be 72 inches, then you need a cylinder that is 24 inches long. Then, you need to figure that moving two 1.5 inch rods 24 inches will require about 85 cubic inches of fluid. Now you need to decide how long you want to wait for full cylinder travel. 30 seconds is probably too long, but we'll use it. So now you need a pump that can put out 170 cubic inches of fluid in one minute at 3600 rpm, or a pump that moves about .05 cu inches per revolution. If 30 seconds is too long, 10 seconds would require a pump a pump that moves about .15 cu in per revolution.

I am not a hydraulic engineer, never done anything with it. But the above is grounded in basic geometry.

#22 UncleWillie OFFLINE  

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Posted October 04, 2012 - 07:22 PM

Yes more good answers. Keep them coming I am learning.

#23 UncleWillie ONLINE  

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Posted October 04, 2012 - 07:26 PM

May have found a good online calculator

http://www.baumhydra...es.php?pageid=4

#24 olcowhand ONLINE  

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Posted October 04, 2012 - 07:26 PM

My home built FEL has 2" lift cylinders, 1/4" hoses from splitters to cylinders, then 3/8 hose back to the spool valves. I'm using a hydraulic pump from a Case 446 which is around 10+gpm at 3600rpm, with relief set at around 750psi. Now while I have never weighed how much it can lift, it will lift far more than is safe. I'd have to guess I've loaded it to 500lb easily, and it will lift more.
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#25 Guest_rat88_*

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Posted October 04, 2012 - 07:30 PM

Refer to previous post... Reinventing the wheel can get expensive. Can I get an Amen! If it works the first time, great. If it doesnt try, try again That can get expensive, not to mention the possibility of injury on a project like this. Take the easy way and buy something that is already proven to work.

Edited by rat88, October 04, 2012 - 07:31 PM.


#26 Toolpartzman ONLINE  

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Posted October 05, 2012 - 05:49 AM

EDIT: In order to try and stop people from reading the first post here and giving me the same tired answer I am going ot include this at the top I will leavy my original post below, but I would really like an answer to the quistion I have asked now a million responses saying it cannot be done.

REVISED POST

Ok lets try again. Take the tractor out of the equation. Lets assume I have a super monster oversized commercial 750000 pound industrial tractor that I am going to build a loader for.



What PSI pump and diameter cyls and hoses are needed to make it lift 1000 pounds .








After I posted the original post I was contacted by a guy I have been trying to reach for a couple of days about a bigger tractor that would become the basis for the loader. .



original post

I am thinking of building a loader for one of my tractors. Haven't decided which one yet. (yes I know I will have to beef up the front axle) But I have been looking at different sites about hydraulics trying to educate myself. Only problem is that the ones I found were for engineers and by engineers. I am not an engineer, I have only ridden on a train once. So what I need is some hydraulic help. Can someone tell me in simple terms without a lot of math what kind of Hydro system I would need to lift approximately 1000 pounds + the weight of the loader arm and bucket so figure about 1300 tops. I want to be able to lift it around 5 feet high to be able to load a pickup truck over the side so there will be a bit of lift needed. What size pump and cylinders am I looking at needing?

The reason I am wanting about 1000 pounds of lift is it will be picking up scrap metal and I want plenty of leeway on the lift.

OK, Yes it CAN be done, but it will require one of two things.
1) A hellava lot of money
or 2) A hellava lot of math

The force a hydraulic ram will push (at the end of the rod) is equal to the pressure in PSI multiplied by the area of its cylinder.
A 4" bore cylinder has an area of 12.57 inches.
a pump capable of moving fluid at 500 psi will lift 6285lbs
100psi will lift 1257 lbs
5000 psi will lift 62, 850 lbs
Your starting point is the above formula- A (sq inches) x Pressure (in PSI) = force
Since you've determined your force to be 1000 lbs, then your answer is in
to find cylinder size A= Force/Pressure
or to find pressure P= Force/ A
There's dozens of combinations to lift 1000lbs- straight lift, there's hundreds of combinations to lift 1000lbs thru an arc (such as a bucket loader)

No you don't need to be an engineer to solve your issue, but you will have to run lots of high school math just to reach a point where you hook it to a GT or pickup or whatever. A GT doesn't have to weigh 1000 lbs to lift 1000 lbs, but when you get that 1000lbs overhead its got to push that 1000lbs back against something.
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#27 dave8338 ONLINE  

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Posted October 06, 2012 - 11:06 AM

A pair of 2 1/2" cylinders with 1 1/2" rams (so they won't buckle when raised and moving) and a stroke of 24" will be more than over-kill.

If your pump puts out 1200 PSI, figure on only needing 50% of max pressure to avoid pump stall and put it together.

You'll also want to keep your GPM pump output in mind as a 10GPM pump with those cylinders will launch your load over your head. Keep in the range of 3-5 GPM at 1200 PSI and plan on installing an adjustable flow regulator so that you can fine tune your lifting rate of speed.
Heat (fluid temps) will not be an issue as you're not running a hydro motor with continuous flow. You can run a seperate tank for the fluid OR build it into the loaders arms at the rear.

Hope this helps.

#28 Guest_rat88_*

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Posted October 06, 2012 - 12:30 PM

I posted a safety video in the homade wheel hub thread and got to thinking about this one.
Hydraulic fluid can be pretty dangerous, not to mention the risk of under engineered equipment lifting more than is should.

This is a cheesy safety video on hydraulic injection. Its worth a look if you are not familiar with it
WARNING>> GRAPHIC PICTURES!!!!





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