Splitter pump size

[wrx-snowdrift]

Toying with building a new splitter. I might have access to a 18HP Briggs opposed twin. Wondering what size 2-stage pump would pair well with this.
22gpm says 12hp minimum so maybe a 18 is overkill?
28gpm says 15hp minimum but I also found one site saying 15 was the minimum but 20+ was recommended.

I have a 5x24 cylinder.

 

[homemade]

Go with the 28. You can always drop the relief pressure to keep from stalling the motor. But, with a 5” hydraulic cylinder, you couldn’t see much above 2000 unless your running a box wedge or 6 way.

 

[rancher2]

I would go with a 28 I have run a 28 for years on a 16 Hp Briggs twin with no issues. I have the relief pressure set at 2800 Psi. It will be worth the extra dollars to pickup some speed on the cylinder.

 

[Ryan'smilling]

Another vote for the bigger pump. With a 5" cylinder you'll appreciate the extra flow. I run my splitter under 2000 psi because my tractor is underpowered for my pump, but it's rare that the 5" cylinder has a problem. And I'm pushing everything through a 4-way wedge.

 

[cantoo]

Keep in mind you need the bigger flow valve too. And bigger hoses. The old domino effect.

 

[dave_dj1]

Keep in mind you need the bigger flow valve too. And bigger hoses. The old domino effect.

and larger ports in the cylinder to really see any benefits of that large of a pump over a 22 gpm pump.

 

[homemade]

Very true. A lot of the standard valves are only rated up to 25gpm.

 

[cantoo]

Here's my big 4 x 36" cylinder. I assumed the inside holes would be bigger on a big cylinder. The welded bung was but the cylinder hole was small.

 

[ChoppyChoppy]

When I resized my pump, I put in a 30gpm. I'm running a 35hp Kubota. I had to dial the pressure relief down, otherwise it would stall out the engine. This is a single stage pump though.

What is the flow of the 1 stage, that would be what you'd need to check.

Also keep in mind that the return stroke of the cylinder will be higher than pump flow. This # depends on rod size. Like my setup, it was around 60 or 70gpm on the return, though my cylinder has a large rod.

 

[wrx-snowdrift]

Thanks for the replies everyone.

Good call on double checking the control valve and the ports on the cylinder. The cylinder is a 5 x 2 x 24 not sure on the ports, I'll have to check sometime.

I read a good thread on here about using larger than normal hoses and fittings as well as minimizing 90 degree bends and such to keep the oil temp down so I'll put that into the plan.

When I resized my pump, I put in a 30gpm. I'm running a 35hp Kubota. I had to dial the pressure relief down, otherwise it would stall out the engine. This is a single stage pump though.

What is the flow of the 1 stage, that would be what you'd need to check.

Also keep in mind that the return stroke of the cylinder will be higher than pump flow. This # depends on rod size. Like my setup, it was around 60 or 70gpm on the return, though my cylinder has a large rod.

First stage is 28 gpm at 600 psi
Second stage is 6.7 gpm at 3000 psi

 

[Yarz]

If you can afford to up-size everything, I agree with others here: go 28. You may want to think about adding a dump valve for the return stroke so not all of the fluid has to go through the valve.
Here's a clip of a spreadsheet I built to calculate the cycle time, tonnage, and gal/min out of the cylinder on retract. I wasn't sure what your rod size is, so I included a few.

 

[all go no show]

Are these speeds and rates based off of using 1/2" inlet and outlet?

 

[Yarz]

My apologies, I forgot to mention that they are theoretical.
The calculations assume you can fill and empty each side of the cylinder at the rate the pump is pumping. Any restrictions due to hose diameter or length, cylinder port size, or bends will not be taken into account. I made it primarily to compare cylinder and pump sizes to get an estimate of the effects of changing each.