Two stage hydraulic pump power requirement. ??

[CalG]

Comparing three readily available "splitter pumps".
One is rated 3.4 gpm at "high power" (3000psi), and 11 gpm at "high speed" with the cross over adjustable between 400-900 psi. (or so)

A second pump pump is rated 3.2 gpm at "high power", and 13 gpm at "high Speed", also with adjustable cross over similar to the first pump.

The third pump is rated 3.0 gpm at "high Power", and 16 gpm at "high speed", the cross over is adjustable similarly.

What determines the gas engine Horsepower requirement for these three options all feeding the same push cylinder?

My "common sense" tells me that as all three pumps are so closely matched in "high Power" capacity, they are for practical purposes they are the same pump on the 1st stage, and should require similar input power.

But my common sense on two stage hydraulic pumps is bolstered by over 65 years of not looking into such things. ;-)

I welcome discussion on the practical matters on these two stage splitter pumps, with an eye towards cycle time reduction.?

 

[4570Man]

I’ve never encountered a 2 speed pump that would stall the motor on the high flow setting. I’m guessing the high pressure side is the harder to turn setting. There’s calculators available to determine the HP required for a given flow and pressure. Or you could research the formula and calculate yourself of you’d rather do that. Don’t the pumps have a recommended HP?

 

[Fallon]

PSI * GPM / 1714 = HP. Horsepower Calculator - Metaris Hydraulics so it's a pretty easy equation if you plug in 2 of the 3 variables & you can compare from there.

 

[CalG]

PSI * GPM / 1714 = HP. Horsepower Calculator - Metaris Hydraulics so it's a pretty easy equation if you plug in 2 of the 3 variables & you can compare from there.

Do you run the calculation at the 3.4 gal/min, or the 11 gal per min, and what performance difference should I expect when the round is buried 6 inches into the wedge and a tangled knot is encountered?

 

[Fallon]

Do you run the calculation at the 3.4 gal/min, or the 11 gal per min, and what performance difference should I expect when the round is buried 6 inches into the wedge and a tangled knot is encountered?

The power & speed stages each have their own PSI & GPM combos. High GPM & low PSI then kicks to high PSI & low GPM. Calculate each separately & you'll get the HP requirements at each stage. You can generally adjust the relief valve for max PSI & the kick down PSI where it shifts from high flow to high pressure. Use those numbers for your PSI calculations.

As far as performance, just multiply the PSI times the surface area of the piston in the cylinder. That gives you force. Generally you assume high pressure for max force, but you can easily do it for the high speed stage as well.