Log Splitter Hydraulics

[jdb4whlr28]

I recently purchased a log splitter off a gentleman for fairly cheap. He mentioned the cylinder would probably have to be rebuilt as it was leaking under pressure. When I picked it up from him, everything was running as expected (cycle time, auto retract) but when I got home I went to try it out and the cylinder cycle time was outrageous. The thing barely moves now. Also if you use the detent for the auto retract, the pump starts screaming when it gets to the end of the cycle. My first thought was the pump was bad so i put a new pump in and its still doing the same thing. Any thoughts???

 

[motownbrowne]

Collapsed suction hose from the tank to the pump?

 

[rswyan]

Check the hydraulic fluid level ?

 

[triptester]

Check for coupling slippage between engine and pump.

 

[Leejohn]

Lower the 3pt a little and see if that helps. If so the feedback needs to be adjusted. Also check quick couplers.



Man what was I smoking when I wrote the above?

 

[muddstopper]

If the cyl is leaking, good chance its low on oil. As for the screaming in detent, I would guess that the detent relief is set to high and probably just needs a little adjusting.

 

[4570Man]

What gpm pump did you get, and how big is the cylinder? Assuming it's in the fairly typical range of a wood splitter with a 4.5 cylinder and a 11 gpm pump it should cycle probably decent. Not a speed racer put a lot faster than hardly moving. I'd definitely check out the simple stuff like collapsed suction hose, low oil, and clogged oil filter. Also check the relief pressure on the pump and some valves have a relief pressure valve.

 

[jdb4whlr28]

Thanks for the info all! I checked the oil level and its topped off. I also checked for slippage of the coupling as my first guess was the pump wasn't working properly. There's definitely no slippage. The pump is a 11.5 GPM 2 stage pump. The guy I bought it from changed the fluid/filter less than a year ago so I'm doubting the filter is clogged but I will buy a new one just to rule that out. The tank suction line doesn't seem to be collapsed at all. However the line going from the filter back to the tank is questionable. But that is on the pressure side of the pump. Could that possibly be the issue?

 

[CincyFlyer]

Did you rebuild, or at least check, the cylinder?

 

[LD1]

Does l"leaking under pressure" mean that its leaking oil onto the ground? or just leaking internally?

 

[jdb4whlr28]

I plan on rebuilding the cylinder, just haven't gotten around to it yet. It was leaking on the ground near the wiper seal. The weird thing is it the speed would kind of snap back to normal every once in awhile when I first started messing around with it which is why I really thought it was the pump. But the past couple times I've messed around with it I can't even get it to do that anymore. From the fully retracted position it takes well over a minute to get to full extension.

 

[HarryVanderpool]

Regardless of any thing else, the logical first step is to fix known problems first.
When you know that the cylinder is freshly rebuilt, then you can continue.
Until then you are just wasting time.

 

[4570Man]

Unless there's oil pouring out of the cylinder it should extend regardless of what condition the inner seals are. I'd look elsewhere for the problem.

 

[CincyFlyer]

Unless there's oil pouring out of the cylinder it should extend regardless of what condition the inner seals are. I'd look elsewhere for the problem.

If that were so they'd just leave the seals out.

 

[4570Man]

If that were so they'd just leave the seals out.

No, because it won't retract.

 

[TemporaryKubotaOwnerMark]

Regardless of any thing else, the logical first step is to fix known problems first.
When you know that the cylinder is freshly rebuilt, then you can continue.
Until then you are just wasting time.

Yep.

No matter how many people tell you, "Oh, it couldn't be that!", always fix known problems first. Then you know.

 

[LD1]

I guess I would want to be sure the issue is with the cylinder FIRST. Rather than rebuilding it for no reason.

A minor leak out of the gland/wiper seal is not gonna cause the problems you describe. As 4570man said, the inner seals could be totally shot and the cylinder would still extend.

Symptoms of inner seal problem would be difficulty retracting or not retracting at all. Extending instead of retracting. And low power.

You dont describe any of those symptoms, so I'd look elsewhere for the issue.

 

[LD1]

If that were so they'd just leave the seals out.

They do on some single acting cylinders. Like snowplow angle cylinders. There is no piston and no piston seals at all. Simple displacement principal. Pumping oil into the body of the cylinder displaces the rod. No piston required. But without a piston and piston seals, there is no way to retract the cylinder.

And on a cylinder that actually has a piston, but damaged piston seals....the leaking by the piston will cause a lack of power. But in the case of a splitter where there is no load when just trying to dry cycle, it should still extend.

 

[Texasmark]

However the line going from the filter back to the tank is questionable. But that is on the pressure side of the pump. Could that possibly be the issue?

The filter needs to be on the ï½¾" return line to the tank, usually right at the tank inlet. There should be very low pressure drop across the filter. I installed a pressure gauge right at the inlet to my filter to tell me when/if it clogs. Pressure readings are barely visible on a 100 psi gauge which is what you want...no pressure drop.

The feed line to the pump from the tank needs to be at the bottom of the tank and preferably the tank is mounted above the pump to get gravity feed to the pump inlet. The pump outlet is probably ï½½ pipe.....whatever size hole is in the pump...don't choke down this line to the control valve, and the inlet needs to be at least ï½¾" tubing from the sump. Mine is 1" and no problems supplying the pump when it wants fluid.

Heating of the fluid to excess is caused by cavitation somewhere caused by a restriction. Noise is usually audible with cavitation...whining. There will be some heating caused by compression of the liquid in the pump.
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I don't know where the funny marks come from in postings on this site. The "T1/2" stuff preceeding a dimension like "three quarters of an inch" have nothing to do with the ¾" measurement.

 

[HarryVanderpool]

You dont describe any of those symptoms, so I'd look elsewhere for the issue.

Actually, he does.
He says that upon retracting in the detent position, it just sets and screams.
That may be because it cannot quickly build the pressure to bump off the detent after retraction.