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Building my own Electric Hydraulic Shop Press.

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GoceKU

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First off this is my first endeavor in high pressure hydraulics, any advice is much appreciated, i've bought couple of parts over the last few months for the hydraulic side of this build, and i'm leaving the heavy metal frame build for last, many because i'm confident i'll should be able to fabricate it in couple of days.
First of the recently acquired part is a pair of hydraulic cylinders, one come with some fittings and couplers wich i may be able to reuse, the cylinders are stabiliser legs from a crane or a concrete pump, it has a stroke of 55 centimeters shaft diameter 56mm and cylinder inside diameter of 80mm, i've disassembled the first cylinder i got to inspect it and clean it. Also the front of the cylinder has a removable front attachment, using a spring pin, which is ideal for attaching different tooling on it, can someone calculate what pressures i need run to get 20-30 tons out of 80mm cylinder.
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rgray

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f350ca

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You get some great deals at your scrap yard, here they think their buying sawdust and selling gold.
To get 20 tons you'll need 5100 psi, fairly high pressure, I like to stay below 2000 and go for larger cylinders. Makes for cheaper controls and hoses.

Greg
 

whitmore

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#4
First off this is my first endeavor in high pressure hydraulics, any advice is much appreciated, i've bought couple of parts over the last few months for the hydraulic side of this build...
... what pressures i need run to get 20-30 tons out of 80mm cylinder.
About 100 atmospheres is OK for an O-ring; two or three can get you higher (like, 200 atmospheres = 3000psi= 20 MPa), but for higher
pressure one uses supported seals of various designs. A first step will be to open up the cylinders and look at
the glands and seals (or assume low pressure only, or do a controlled test...).
10kpsi is the usual maximum pressure with any flexible hoses.
 

GoceKU

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#5
Those cylinders are a bit of a disappointment, i will need around 700 bar to get close to 40t press. so i'll look for the biggest in diameter cylinder i can find, other parts i have is this hydraulic pump, is russian made, only 140 bar but pretty high volume, also i have this new valve with large ports for high volumen, it seems to have a regulator built in, not sure what pressures is rated for.
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