Hydraulic Press - GPM needed

One use I've seen such a press used for in the machine shop is as a vice, so you need V blocks for the deck and on the piston rod to hold things like hyraulic cylinders for taking them apart (the ones that twist apart with a 4' pipe wrench) and the v blocks are also handy when straightening (stretching) a bent shaft or cylinder piston rod.

Gerald J.

What Horse Power do you have available to use? That is probably going to be your biggest problem.

You can figure GPM * PSIG * .0007 =Pump HP required.
(that is calculating at about 83%- 84%% efficiency)

A 6" cylinder with a 4" rod will have a net extend area of 28.27 sq. in. and a net return area of 15.708 Sq. In. 3000 PSIG will give you 42.41 tons of press.

At 1 GPM of pump delivery you would have 0.14"/Sec extension speed and 0.25"/Sec of retract speed and and at 3000 PSIG pressure it would require right at 2HP to get the job done.

Of course double the GPM twice the speed and twice the HP.

If you need more cylinder speed you will either have to look at a 2 stage pump or greater Hp.

Another question, Williams pump says it runs at 1000 RPM but all the ag-duty electric motors I am looking at run at 1750 RPM. How can that work right? Thanks for your help!

You could learn much quickly by looking at what has been in use for decades.

You do need a really sturdy frame to hold the cylinder and the work platform. Work platform planks of 2" thick steel slabs stand the pressure but don't move easily when they get in the way. I you figure the stresses, you want to be extremely conservative because design stresses that survive allow for significant deflection and in a press that means misalignment and destruction of the work parts.

Gerald J.

It is a bi-directional piston pump built to be driven by a PTO shaft. The relief valve appears to be built in the tank and to be non adjustable (not a good thing for your press).

I would recommend you use something with a relief valve that is adjustable and readily accessible, and combine that with a pressure gauge so that you keep the pressure adjusted as low a pressure as you can to get the job done.

The control valve should be remotely mounted in a safe operating place that can be used to throttle the flow.

A 1 GPM flow rate would probably give you a good safe usable travel speed.

If you already have the unit then you might be able to adapt it so that it would work.

I would look and see if you could remove the valve from the top of the unit and run the hoses out and install a remote mounted adjustable relief valve and plumb in the control valve downstream of the new adjustable relief valve.

Since this pump is probably not rated for any sideload on the input shaft you would need to use a jack shaft with pillow blocks to drive the input (flex coupling recommended) and install pulleys of the correct ratio between the motor and the pump to turn the pump the proper speed.

If you use this unit I would probably turn the input at about 600 RPM and use the 2HP motor on it.

0.5 cipr (8.2 cc/rev.)
maximum pressure 3500 psig (241 bar)
maximum speed 1000 rpm
bi-rotational
typical performance 1.66 gpm (6.3 lpm) @ 1000 rpm and rated pressure.

Based on the figures you give, I think it should work just fine, right???

I went on the Williams site and looked at the model 20, I really can�t tell if the valve is 3 way or 4 way or if it is an optional choice.

The bearings appear to be needle so radial loading from a belt drive might not be a problem.

I can�t really get enough information on the specifications of this unit to have much of a handle on it, but I rather doubt you would be happy with the performance.

Like I said before you can probably make this unit work if you don�t mind waiting a couple minutes for the Cylinder to stroke when you are sitting up the press.

I think you would be happier if you used that 5 HP motor on a 2stage pump. Williams does make some 2 stage Power Packs that would do a great job but they are pricey (you can see a F98X Model at the Surplus center web site).

Look at the log splitter pumps at the �Surplus Center� or �Northern Tool�. These would give you fast setup speed and then slow down when you reached actual press conditions.

If you put your own system together it could be cheaper than using the packaged unit (depending on what parts you can scrounge up).

For typical shop use, pressing things apart or together, SLOW is the way to go, NOT fast, anyhow.

Surely your cylinder (I forgot the size you posted) doesn't even hold a gallon of oil, so even a 1 GPM pump would more than take it to full stroke in a minute's time.

How the heck fast do you want it to go, anyway???

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