Hydraulic pump and gasoline engine

[Eikrem]

Hello all hydraulic experts in here.
Been reading on this forum for a while now and I see there’s a lot of good stuff in here.
Just got a 16gpm tandem pump and need to know if It’s my engine is to small or not.
In Norway this engine is listed as a 15 hp but in reality is a 13 hp if im correct.

Please see link of the pump.
https://www.ebay.co.uk/itm/Flowfit-...SPLITTER-PUMP-HI-LOW-GPCBN160PC-/251442992365
Please see link for the engine.
https://www.nrracing.com/product-p/eng-oem-hf-15hp.htm

 

[timbrjackrussel]

For every Gallon per minute at 1500lb psi you need 1HP to turn the pump. So, for a pump to put out 4 gallons per minute at 3000psi it would need 8 hp.

 

[Streblerm]

A 13hp engine should be more than enough with a 16 gpm two stage pump on a log splitter. 8hp should be enough. 13hp is marginally enough with a 22 gpm pump.

http://www.ruggedmade.com/Log Splitter Pump Spec Sheet 11-28GPM.pdf

 

[Ryan'smilling]

If it's not quite enough HP you can dial back the relief valve so it can't generate full pressure and stall the engine.

 

[4seasons]

For every Gallon per minute at 1500lb psi you need 1HP to turn the pump. So, for a pump to put out 4 gallons per minute at 3000psi it would need 8 hp.

While this information is technically correct it is somewhat misleading. It applies to single stage pumps, where log splitter pumps are generally 2 stage. They are essentially 2 single stage pumps stacked together. Most 16 gpm 2 stage pumps are a 3 gpm pump with a 2500-4000 psi rating and a 13 gpm pump with a 400-900 psi rating. The 3gpm pump is always turning, but the 13 gpm pump will kick out after pressure reaches whatever the setting is, say 600 psi. So using your formula, you need less than 1/2 HP for every gpm on the 13gpm pump plus the 3 gpm pump for about 7 hp. There is normally a slight stall as the high flow loads up to pressure so add an extra HP or 2 to push thru. Then the 3gpm pump up to 3000 psi would need 6 hp.
The simple answer is while I am not familiar with that particular pump, most 2stage 16gpm pumps call for a 8-9 HP engine.

 

[muddstopper]

1 gal is 231cuin. the pump gear sets are listed in cc perrevolution and cuin perrevolution. I dont do metric so you can do the conversion from cc to cuin. The size of the pump in cuin is how much the pump produces per revolution. The rpms of the engine will deterime how much flow the pump will produce. Each section in a two stage pump is rated to produce a different amount of flow. The larger section of the pump (bigger cuin) will produce the most flow, but that flow is limited by a internal unloader valve. This unloader valve can usually be adjusted for different pressure rates and that rate is usually much lower than maximum pressure. The smaller section of the pump is also produceing flow, but this sections pressure is regulated by the relief valve that is usually set at max pressure. Both sections are produceing flow at the same time until the unloader valve settings are reached, at that time the unloader valve dumps the highflow and the smaller section of the pump continues to allow pressure build up. Since the flow requirements are much lower than the maxium flow rate, it takes much less engine power to turn the pump. With that said, with a reduced flow and high pressure, the engine needs to be big enough to turn the the lower flow at maximum pressure rate. I havent done the math, but the low flow rate is usually around 4 or 5 gpm. Typical max pressure is usually set around 3000psi. Using the 1gpm@1500psi, you would need about 8-10hp to turn your pump efficiently. Of course you will have some residual drag as the high flow oil is still being produced, but the pressue power required is minimal and a result of friction, not actual work.

 

[4seasons]

1 gal is 231cuin. the pump gear sets are listed in cc permin and cuin permin. I dont do metric so you can do the conversion from cc to cuin. The size of the pump in cuin is how much the pump produces per revolution. The rpms of the engine will deterime how much flow the pump will produce. Each section in a two stage pump is rated to produce a different amount of flow. The larger section of the pump (bigger cuin) will produce the most flow, but that flow is limited by a internal unloader valve. This unloader valve can usally be adjusted for different pressure rates and that rate is usually much lower than maximum pressure. The smaller section of the pump is also produceing flow, but this sections pressure is regulated by the relief valve that is usually set at max pressure. Both sections are produceing flow at the same time until the unloader valve settings are reached, at that time the unloader valve dumps the highflow and the smaller section of the pump continues to allow pressure build up. Since the flow requirements are much lower than what the maxium flow rate, it takes much less engine power to turn the pump. With that said, with a reduced flow and high pressure, the engine needs to be big enough to turn the the lower flow at maximum pressure rate. I havent done the math, but the low flow rate is usually around 4 or 5 gpm. Typical max pressure is usually set around 3000psi. Using the 1gpm@1500psi, you would need about 8-10hp to turn your pump efficiently. Of course you will have some rsidual drag as the high flow oil is still being produce, but the pressue power required is minimal and a result of friction, now actual work.

I thought I went into a little to much detail.

 

[Sandhill Crane]

I thought I went into a little to much detail.

Now I have a better idea of how hp and cu. in. relate to gpm.
Cu. in. online, like Surplus Center, on a pump or motor never connected before.
Thanks muddstopper!
I still have a question however.
Is there a story behind your 'muddstopper" handle?
Inquiring minds want to know...

 

[muddstopper]

Now I have a better idea of how hp and cu. in. relate to gpm.
Cu. in. online, like Surplus Center, on a pump or motor never connected before.
Thanks muddstopper!
I still have a question however.
Is there a story behind your 'muddstopper" handle?
Inquiring minds want to know...

well the story goes something like this. 20 years or so ago, I was into doing some lite landscapeing and hydroseeding. I did some work for a older lady that was having water problems around her house. I regraded the slope and what ever it took to turn the water away and everything dried up .She called me her muddstopper because I got rid of the mud. Of course my helpers thought this was funny so they started calling me muddstopper, so I decided to just go with it. Kind of funny now because nobody around here calls me muddstopper anymore or even knows it used to be my nickname.

I thought I went into a little to much detail.

I corrected a small detail in my post. I said pumps where measured in cuin/cc per min, and its supposed to be cuin/cc per revolution. For every turn of the pump shaft it displaces a set amount of flow. The faster it turns the more it flows and when it turns fast enough to displace 231cuinmin it will be pumping 1 gpm.

 

[Eikrem]

Some good awnsers!!
Thanks to all for the contribution.
Any of u guys who uses a kickout controll valve,and is able to explane setup?it states maximum kick out pressure is 800 psi. Will that be anough to split the log before the cylinder retracts.also want a cylinder to adjust the knife.
Thanks in advance.

 

[muddstopper]

800psi isnt a lot of pressure, but with a 10in bore cyl it will produce over 30tons of force. With a 5in bore cyl 800psi will only produce about 7.5 tons of force. So the answer of will 800psi be enough to split wood, the answer is yes and no.. It all depends on what kind of wood, how much force does it take to split it, and what other combination of parts you are planning on using to do the work. Then you have to ask yourself how fast do you want to split the wood. With everything being equal with pressure and flow and other varibles such as stroke and shaft size, the 10in bore cyl is going to be about 4 times slower than the 5in cyl. To get the speed you would have to increase pump flow which would also mean increaseing the hp required to produce the flow. With that said, the 800psi required to produce the kickout on the auto return valve is usually used to retract the cyl, not extend. Retracting the cyl is putting pressure on the rod side of the cyl. This side of the cyl piston will have a smaller surface area and will produce much less force than if the pressure in on the opposite side of the piston. Usually this kickout pressure is only needed to retract the cyl and then allow the valve to shift into center position when the cyl is fully retracted. It is not meant to be used to split wood so minimal pressure is only needed to make the cyl retract without load. The control valve should have a adjustable relief that can be set seperately from the retract detent and enable you to adjust for full system pressure on cyl extend and spitting wood.

 

[Eikrem]

Thank u for exlaining.so the 800 psi is not built up on the piston side but on the rod side?? Correct me if I’m wrong. If so I understan.
The cylinder is only 60mm id and rod is 40 mm. Area 28,2. So it will move quickly

 

[muddstopper]

60mm=2.36inches, 50mm=1.57inches. Thats a pretty small cyl for a wood splitter. Yea, at 16gpm it will be pretty fast. at 16gpme it will extend at 14inches persec and retract at 25inches persecond. Way to fast for me. We used to have some 4in bore x 8ft stroke cyl that would cycle 13times permin, but nobody had any hands or fingers around it.

 

[Eikrem]

I know. I’m thinking of upgrade to a 4” and still be fast enough for me.

 

[cantoo]

What kind of wood are you splitting in Norway? I'm assuming birch, spruce and pine? These are normally easier to split woods so your cylinder size can be smaller. I'm splitting nice straight grained ash with a 4 1/2" cylinder I could have gotten away with a 3 1/2" but when the ash is gone I will be splitting maple.