Log Splitter Hydraulics

[Texasmark]

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.

Following what I said should help him solve that fluid starvation problem causing the squealing.

 

[LD1]

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.

What you just said contradictory.

Sitting and screaming is a sign of pressure.....not lack of pressure to bump off detent.

If the piston seals were so shot that it wouldnt build enough pressure to bump off the detent....fluid would simply be bypassing the piston seals and right back through the open work port to tank.

There are many steps one can take in determining the condition of the cylinder. I dont like guessing and just throwing parts at something on a whim as is seen so many times here when it comes to hydraulics which are a mystery to so many.

Sure you can replace/rebuild the cylinder, replace the valve, replace the pump....eventually you will get the right one.

But I believe in troubleshooting and diagnosing the problem first.

 

[4570Man]

Based on the process of elimination I'd say you have an oil delivery problem in the lines. On the suction side sounds more likely. You said the cylinder worked when you bought it with no use mentioned afterwards. I doubt the cylinder went bad over that period. The cylinder worked before so that means your pump previously worked. Then you changed pumps. I doubt you have 2 bad pumps. So that narrows down the problem IMO. You could further trouble shoot the cylinder by attempting to pull the ram out with a come along if you think it could be the problem.

 

[jdom84]

I had very similar experience on a log splitter once... turned out to be the valve. The seals or something inside were trashed and the pump couldn't build pressure at all because it would just dump the pressure back into the return line.

As soon as the wedge made contact with the log the pump would make a "scream" (more like a whine noise). When in detent, it would do the same thing... didnt have enough pressure to pop the detent back. I had a non-detent valve laying around that I threw on it and it worked just fine.

 

[jdb4whlr28]

Thanks for all the info guys! I ended up taking the cylinder apart because it had to be rebuilt anyway and o-rings really arent that expensive. Unfortunately my local hydraulics shop had to order the seals and hopefully those will be in tomorrow. Once I get the cylinder rebuilt I'll update this thread. I'm quite certain its not the pump because, like mentioned above, it's pretty unlikely I had 2 bad pumps. The valve on the splitter is only a couple years old however I haven't tried changing that out yet. That will be my next go to if the cylinder rebuild doesn't take care of it. The o-ring on the piston wasn't gouged or torn but it was very disfigured. The secondary seals on the piston were pretty beat up though.

I took the return line off the tank from the filter and started it up to see if the pump was actually producing pressure and fluid came out of the filter outlet at a pretty good rate. So I don't think there is a suction line issue here either.

To weigh in on the piston seal discussion above (and I'm by no means an expert here) but if those seals were bad I'm having trouble seeing how I'd only have retraction issues. The valve would allow pressure into cylinder and if that pressure just blows past the piston seals how would the ram extend? Talking this out it kind of makes me think it could be the seals because it does extend very slow (lack of pressure build up?)

 

[motownbrowne]

If the seals are bad it'd still extend. The pressure is gonna go through the valve, and into the cylinder. If it goes through the seals onto the return side, the whole cylinder is now pressurized the pressure will also go through the other lines and back to the valve. But since the valve is open in the other direction, it can't get back to the tank. The only place for the pressure to go out created by the piston moving outwards.

 

[ovrszd]

If the seals are bad it'd still extend. The pressure is gonna go through the valve, and into the cylinder. If it goes through the seals onto the return side, the whole cylinder is now pressurized the pressure will also go through the other lines and back to the valve. But since the valve is open in the other direction, it can't get back to the tank. The only place for the pressure to go out created by the piston moving outwards.

Good description. If the unknowing read it they might have to read it a couple times. But eventually it makes sense.

I believe this scenario to be the hardest to understand by everyone. Hopefully it can be discussed without condescending comments.

 

[jdb4whlr28]

So the fluid that goes back to the valve gets put back into the pressure side? I guess I always thought that fluid getting pushed out of the cylinder went back to the valve which directed it back to the tank

 

[ovrszd]

So the fluid that goes back to the valve gets put back into the pressure side? I guess I always thought that fluid getting pushed out of the cylinder went back to the valve which directed it back to the tank

If the valve is in the "neutral" position it closes both cylinder ports. The cylinder cannot retract, regardless of it's internal seal condition, because there's no space in the cylinder for additional rod.

 

[jdb4whlr28]

If the valve is in the "neutral" position it closes both cylinder ports. The cylinder cannot retract, regardless of it's internal seal condition, because there's no space in the cylinder for additional rod.

That part makes sense to me. But if I open the valve to extend the cylinder, and the seal is no good, wouldn't the fluid just go past the seal and back to the valve and then back to tank?

 

[ovrszd]

Yes, a portion of it would. If seal is bad enough you might notice slow cylinder extension. To result in no extension the seal would have to "leak" at a gpm matching the tractor's gpm at that circuit.

 

[jdb4whlr28]

Ok, that's what I was thinking. So going back to earlier posts on here it might actually be the cylinder seals that are causing the slow extension. I called the hydraulics shop and all the piston seals are in but the wiper seal wont be in until tomorrow. So looks like I'm going to have to wait another day to find out if this fixes it.

 

[ovrszd]

Hoping you get good results. Let us know the end result. Thanks for posting.

 

[jdb4whlr28]

So I got the cylinder all rebuilt today. It no longer leaks under pressure and the piston seal seems to have fixed the outrageous extension/retraction time! Thanks everyone for your advice on this one!

 

[ovrszd]

So I got the cylinder all rebuilt today. It no longer leaks under pressure and the piston seal seems to have fixed the outrageous extension/retraction time! Thanks everyone for your advice on this one!

That's great!!!! Thanks for the update!!!! Now get to work.......

 

[CADplans]

That's great!!!! Thanks for the update!!!!

Now get to work.......

We want pics of split wood!!


:laughing:

 

[TemporaryKubotaOwnerMark]

So I got the cylinder all rebuilt today. It no longer leaks under pressure and the piston seal seems to have fixed the outrageous extension/retraction time! Thanks everyone for your advice on this one!

Yep.

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

:thumbsup:

 

[406ChevySteve]

I went through something similar with an old payloader, the lift cylinders were slow,. It ended up being the control valve. It had a detent valve for the lift arms. I took it apart to find the ball-bearing for the detent was broken and plugging up some of the passages. I removed the ball bearing all together which means I have to hold the valve but thats not a big deal when operating the loader anyway. It was a cheap fix, cost nothing but time, and a good guess at what it might be.