Building a log splitter, need hydraulic help!!

   / Building a log splitter, need hydraulic help!! #1  

dorf

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Feb 25, 2006
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I'm attempting to build a log splitter. I finally got it all assembled and it works great but seems very slow. I have a briggs 5 hp motor, Haldex 11 gpm pump, cross 2500 psi converta valve and a lion 4x24 cylinder. I think the problem is the pump. although it is a 2 stage it starts on the first stage and gets about 2 inches (very fast) and then slows down to second stage (very slow) even under no load pushing and pulling. I placed my filter on the suction side of the pump which I know can be a problem, but I went to tractor supply when I started building this and they all seem to have them on the suction side. Any idea for what wrong?
 
   / Building a log splitter, need hydraulic help!! #2  
Sounds like the low pressure stage might be diverting earlier than it should.

i am not familar with the exact components you are using, is the unloading valve for the low pressure stage of the pump, part of the pump, or part of the directional valve?

Wherever it is, does it appear to have any adjustment?

Also, what is the flow rating of the filter? When used in suction, pressure drop through the filter is critical, since you only have atmospheric pressure to push the oil through.

Would it be easy to temporariy take the filter out of the circuit?

I haven't looked at many log splitters, but i am curious why they don't have the filter in the more traditional location, on the return line?
 
   / Building a log splitter, need hydraulic help!!
  • Thread Starter
#3  
I'm not very familiar with the pump. I bought it new on ebay and it came with no instructions. I did some research and most 18-20 ton splitters use this pump. it does have several ports\bolts on it. on the intake side it has a welded 3/4 line (which i'm using) and a small port above it. on the discharge side it has a 1/2 out port which i'm using, a port just above it. I unscrewed it and it seems to have spring behind it. then a third port just above the one with the spring. maybe someone can tell me what the 3 do that i'm not using. i tried looking at the haldex website for instructions but wasn't able to find any. thanks
 

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   / Building a log splitter, need hydraulic help!! #4  
Did you un hook your wedge assembly from the edge of your piston,and slide it by hand to make sure it aint binding
ALAN
 
   / Building a log splitter, need hydraulic help!! #5  
</font><font color="blue" class="small">( I'm not very familiar with the pump. I bought it new on ebay and it came with no instructions. I did some research and most 18-20 ton splitters use this pump. it does have several ports\bolts on it. on the intake side it has a welded 3/4 line (which i'm using) and a small port above it. on the discharge side it has a 1/2 out port which i'm using, a port just above it. I unscrewed it and it seems to have spring behind it. then a third port just above the one with the spring. maybe someone can tell me what the 3 do that i'm not using. i tried looking at the haldex website for instructions but wasn't able to find any. thanks )</font>

Do you have the part number?

also the suggestion to look for a bind is a good one, the extra pressure to overcome a bind could be putting you in the single pump mode.
 
   / Building a log splitter, need hydraulic help!!
  • Thread Starter
#6  
no thats not it, the cylinder isn't even connected to the slide right now. i like jtfx6552's idea with moving the filter to the return side. i know its the right filter cause its made for a splitter. also i'm going to try to search to the internet some more to find out if you can adjust the pump.
 
   / Building a log splitter, need hydraulic help!! #7  
Are you sure that those splitters that you looked at have filters on the pump supply side? It is possible that they are using a spin on Strainer between the tank and the pump.

A strainer(stainless mesh screen inside spin on filter case) has high flow and typically only filters down to around 100 Micron. A filter(cellulose media inside spin on case) on the other hand is lower flow and typically filters down to around 10 micron. Depending upon the design, the filter itself or the assembly it is screwed onto has a bypass valve in it. If the flow through the filter is too restrictive, the pressure on the upstream side of the filter raises to the point that it forces open the bypass valve and goes around the filter media. This works well when trying to push fluid through the filter assembly. It does not work when trying to suck fluid through the filter as the pump is designed to make pessure and not vacume. Most filter mounts have pressure ports to add a gauge that tells you when the inlet pressure is getting high, indicating a clogged filter.

A typical splitter system would be plummed as follows:
1. Tank with suction strainer installed IN the tank(Stainless mesh screen bonded to a pipe fitting that screws into the wall of the tank) near the bottom so it is always below the fluid level.

2. Suction line connected to the strainer at the bottom of the tank running to the pump input.

3. Pump.

4. Open center control valve(inlet from pump, working ports connected to cylinder ports, outlet to filter assembly).

5. Filter assembly with internal bypass.

6. Return line from filter outlet to tank.

Hydraulic pumps really don't like restrictions on their input. It causes cavitation and heat(oil flow helps to cool the pump) and will quickly wear out the pump. If you are too restricted on the pump suction you could be drawing in air somewhere that is causing your operating difficulties.

There are some schools of thought that say do away with ANY form of input filtration and have NO restrictions on the pump suction as it shortens pump life. The only things in a properly maintained system that can contaminate it are the pump itself and the mechanics downstream of the pump. If you are using and properly maintaining a filter on the fluid before it is returned to the tank to remove any possible contributions, and you have a air filter on the tank breather, there should never be anything in the tank that would do harm to the system.

Good Luck and post some pics of your project.
 
   / Building a log splitter, need hydraulic help!! #8  
Here is the link to the Haldex catalog for the Hi-Lo pumps (2 stage): http://www.haldexbarnes.com/Distributor/Catalogs/HI_LO_PG.pdf

Do you have a pressure gage on the outlet? That would give you a good indication on the condition of the pump.

If it moves fast for 2 inches and then slows down, I would suspect binding. Does it do this if the ram is diconnected?

It's generally good practice to put the filter after the pump, but as long as your not pulling more than 5inHg on the inlet you should be fine. Do you have the direction of flow correct through your filters? Are your inlet hoses tight? If not you could be sucking in air.
 
   / Building a log splitter, need hydraulic help!!
  • Thread Starter
#9  
thanks for all your great suggestions. I'll start by moving the filter and then trouble shoot from there.
 
   / Building a log splitter, need hydraulic help!! #10  
Ron, I hope this is not misdirected at you, since I can't find the old post. Did you recommend a tee in the return line going from filter directly to the pump again with a tee to the tank? In other words, the flow is from splitter valve to filter to tee, with one leg to pump and the other leg to tank? In this system the tank only serves to insure there is enough reserve fluid so the pump is never starved. I'm trying to chase down a slow splitter problem myself.
Thanks, or if this wasn't your post idea last fall, my mistake.
Jim
 
 
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