log splitter diagnosis

[mmzullo]

Hi Guys,
I'm in the process of rebuilding my splitter. Started out as a Lickity splitter. The top beam wore out I'm replacing it with 1/2 steel. Old engine 5 hp honda 11gpm pump. New engine is a 6.5 IC B&S engine driving a 13 gpm pump. With the old engine/pump combo the engine seemed to strain more on the retract cycle then the push cycle( no wood). With the new engine/pump seems to be the same( engine strains to retract). I ordered a gauge to read pressure on both. 1" line on both suction and return with a new filter on the return side. The only parts in the hydro that was not changed where the 1/2 hoses to the cylinder from the valve( Prince 3000 series) and the valve. The valve was leaking from the rear machine plug/port. I took that apart and cleaned the detent valve. I found out from Prince if it leaks from this plug it's excessive return to tank pressure. I replaced the filter and that fixed that problem.
I will put the gauge on the high pressure side of the valve inlet to read pressure on both strokes. I want to change the 1/2 hoses from valve to piston because they both have 90 deg elbows and want to eliminate that F/L.
Am I on the right diagnosis track? If the retract pressure is higher then the push cycle it could be hose or valve?
Thanks
Sorry for this lenghty post.

This is before I replace engine/pump/top plate.

 

[brenndatomu]

Assuming you are not splitting or pushing against anything on the extend stroke, there shouldn't be a lot of pressure when extending or retracting the cylinder unless something is binding. It is possible though that you would hear a slight increase in load on the engine on the return stroke due to the fact that the oil has less piston surface to push on during the return stroke, so less "mechanical advantage".

 

[mmzullo]

Thanks Brennatumu.
Nothing is binding. I think this a recent problem(not really a problem) unless the hose on the retract side is coming apart internally. This was also the same time the valve started leaking but that's fixed now. So should the pressure be the same on the push/pull cycle be the same? No load. Like I say can't remember hearing the engine labor more on the retract cycle.

 

[Oldman47]

Keep in mind that the return stroke uses only that area of the cylinder outside the piston. The area of that is usually a lot smaller than the entire area behind the piston on the forward stroke. Expect the return pressure to be higher when there is no wood to be split on the return stroke.

 

[mmzullo]

Old man.
Thanks

 

[bayard]

i think your return line should be bigger, 1.5 dia.your filter is small. there is a lot of resistance in your small line and filter set up.

 

[kevin j]

What is your cyl size? Bore and rod diam
13 gpm into the rod side area could be up to 20 gpm out the closed side because of the area ratios
Put a gauge on the closed side of cylinder when retracting and see what the backpressure is
Then read pump pressure when extending and when retracting
Could be hose liner or just ports hose valve or filter too small

 

[mmzullo]

24"x4"x2"ram. The return line is 1"coming out of the valve. I'm pretty sure the hose is also 1 ". Should the gauge be low pressure to check the back pressure?

 

[GM_Grimmy]

What is your cyl size? Bore and rod diam
13 gpm into the rod side area could be up to 20 gpm out the closed side because of the area ratios
Put a gauge on the closed side of cylinder when retracting and see what the backpressure is
Then read pump pressure when extending and when retracting
Could be hose liner or just ports hose valve or filter too small

4" bore, 24" stroke, 2" rod at 13GPM you will have about 17.3 GPM on the return stroke coming out of the cylinder. I would make sure you valve is rated for that, or you will be making heat by over loading the valve. Also, should be about 10.5 second cycle time, 6 seconds on the extend and 4.5 seconds on the return stroke. In case you were wondering, that's what I calculated things to be. I say add a second to the cycle time to get real world time, and it should be pretty close.

 

[mmzullo]

The valve is rated for 25 gpm. It's a prince LS 3000 1. It has a 3/4 inlet/outlet. 1/2 ports working ports. The filter is rated for 25 gpms.

If I increase the return to 1 1/2 the bung in the oil tank is still 1".

The new hoses and gauge have not arrived yet. I will first put the gauge on and get a reading before changing hoses to get a better diagnosis on the problem/fix. I want to change the hoses anyway but I dont want to do it all at once.

Thanks for everyone's input. I'm finished splitting for the year so I have time.

 

[loadthestove]

I ran into a similar problem on a splitter I built a few years ago. The retract port on my cylinder and not been milled completely open. After I bored it out my splitter work as it should.

 

[mmzullo]

A little update. The hoses and gauge haven't arrived yet. I had a couple rounds to split. So I ran the new engine/pump combo. Definetly faster cycle times. My question is if the return should 1 1/4 or 1 1/2"s but the valve is only 3/4 return and the bung in the tank only 1" if I get the larger filter housing and plumb the larger hose the restriction will still be the valve and bung in the tank?

Who made there own tanks because the pre-made wont work with the location of mine.

 

[GM_Grimmy]

I'm no expert in hydraulics, but I would say yes it there would be some restriction, but not like having the hose that small. I think if it as having a 90, there's some restriction but going to a bigger hose will allow things to flow better. That's just my thought of it. Hopefully someone that know's hydraulics better can chime in.

 

[Patrick62]

I ran 13gpm pumps on 6.5 engines before. It is marginal, but workable. The half inch hoses are not the problem. I ran them for years. 90's don't help, but I had them as well on a couple machines. It worked. Didn't load the engine that much.... Homemade tanks is all I have on stuff out here.

The only time I ran into a "swap to larger hose" was when I tried to shove 16 gpm thru 1/2 hoses with a marginal engine. It really complained about the idea. Swapped to 3/4" stuff and the complaints went away. Interesting to note that the 14 hp lawn tractor engine had more torque than the 10hp china diesel I replaced it with...

atleast up here the 6.5hp engine was workable on a 13.5 gpm pump. The engine was not enough to pull the 16gpm, I tried. Needed to go to a 8hp.

 

[mmzullo]

Well I put new hoses on the cylinder. I got rid of the 90's and put a gauge on the pressure side line to the valve.
What I found out is. There is 0 pressure on the gauge in neutral.
Test log is a base of a oak 3' diameter round no twists.
When I move the cylinder to extend maybe 100 to 200 pounds. When it hits a log depends what type it goes to 700 800 and splits. When I use my 4 way wedge on the center of round went to about 1500 to 1600 lbs.
Dead stop on the cylinder (full extend) is 2250 lbs.
Retract maybe 100 psi and detent kicks in about 700 psi.
The 6.5 engine is fine. The plus with this engine is it has electric start. It does run an alt also to charge the battery. I would like to find an 8 hp for it.
here are some pics. I made a rear bumper because the pump hangs of the back of splitter.

Thanks for all who gave me Ideas of what to do.
Mike

 

[triptester]

All your pressures sound about right. If you feel you need more pressure the relief in the control valve could be adjusted to where the engine starts to bog down when the cylinder is dead headed at full extension. If your engine can handle the higher pressures without killing switching to a larger would be a waste of time.

 

[mmzullo]

Well I used the splitter on some dead oak and maple. It was almost 90 deg out. I was in the shade. It worked great until the last 4 or 5 logs I noticed on the return stroke the handle in the valve felt weird. I then started to look at the pressure. It would go as high as 1200psi to return to center. Before it was like 7 to 800. I got my temp gun and checked the temp of lines oil tank and cylinder all where about 140 deg. I thought not too bad because it was like 90 out. The Prince manual says 180 is max. But the valve just wasn't feeling right. The oil is new aw32 I think.
I have a few more round to split so I might try tomorrow. Can the valve core be taken out without replacing the seals?

 

[kevin j]

Can the valve core be taken out without replacing the seals?

Maybe, it depends on valve design.
Those with o rings and backup rings can go back in.
Lip seals have to go from one direction or seal lips catch and damage.
Prince LS3000 valve spool comes out spring end but has to go back in from handle end (IIRC). Has lip seal on spool on spring end and lip seal in housing on handle end.

I would not pull spool yet but make sure it is fully shifting. Remove cap on spring end and inspect for something amiss.

 

[sb47]

Well I used the splitter on some dead oak and maple. It was almost 90 deg out. I was in the shade. It worked great until the last 4 or 5 logs I noticed on the return stroke the handle in the valve felt weird. I then started to look at the pressure. It would go as high as 1200psi to return to center. Before it was like 7 to 800. I got my temp gun and checked the temp of lines oil tank and cylinder all where about 140 deg. I thought not too bad because it was like 90 out. The Prince manual says 180 is max. But the valve just wasn't feeling right. The oil is new aw32 I think.
I have a few more round to split so I might try tomorrow. Can the valve core be taken out without replacing the seals?

My hand valve started to feel weird and it started leaking oil out the end cap.
Then it started sticking in the return and not automatically stopping like it should.
I tinkered with the valve and kept it going for several months.
Finally I tried to pull it apart to see if the seals needed replacing.
Bad idea......I never could get the ball bearing back in place.
Must need a special tool for that.
Bought a new valve, and it's worked fine ever since.

I wanted to ask you how you like the truck bed lift on your splitter?
I have wanted to put one on mine for the last several years.

 

[ChoppyChoppy]

2250 is pretty low for max pressure. Is your pump just a single stage? If you have enough motor and the splitter can handle the tonnage, I'd set it to closer to 2800-2900.

If your running in temps like that most of the time, I'd go with a thicker oil, like AW46 if your using 32.