Hydraulics Help Log Splitter

**West OZ Mark** · 16th July 2012, 08:34 PM

As mentioned in a previous post I am putting together a Log splitter. All has worked out fine except I'm having problems with the part I was less concerned about being the control valve. My first valve I used was salvaged from a friends dump pile but after hooking it up it had a really bad oil leek and after a attempted repair job it wasn't going to work.

I purchased a used control valve from a supposedly hydraulic parts supplier but after much headache and me and ripped off (another story) I was given the control valve I have now but I cant get it to work. After much trouble shooting I found that the ram was not moving due to having pressure on both ports at the same time when I move the lever either way.

As you can see in the first picture the letters marked to correspond what is stamped on the control valve. P is where I have the pressure coming into the control valve and T was the return line. A and B are being used for lines to the hydraulic ram. Now in that configuration when I remove both A and B lines pressure comes out of both lines at the same time when I move the controller either up or down.

The way the pressure relive valve is set up is confusing to me and is where I am going wrong I suspect. I would assume that the P should be blocked off and the pressure would come in from the PR and so if excess pressure comes to the valve it will bypass the control valve and go to the T return line but looking inside the valve it is blocked between the PR port to the P port as seen in the photo.

The pressure and return is run at the moment from my Aux on my Bobcat at about 16Gpm but not sure of pressure other than it has a relief on the Bobcat at about 3300psi. I have a pump and petrol motor to run the splitter but need time to finish it all so thought I could use this set up just to get splitting.

Any help to where I'm going wrong would be apriciated...Mark

**pjt** · 17th July 2012, 03:22 AM

It's been a looooong time since I had hands on with hydraulics but I'll suggest a few things, in the forth pic you are saying it's blocked, P can't get to the PR which is what needs to happen should the pressure build to whatever the pressure relief is set at, the over pressure is bled via that external hose back to tank, Is that blockage a non return valve? Probably doesn't need it! To see what is happening there maybe blank off A and B wind the PR valve right down and it at some point it should relieve (squeal) you will have heard it when you lift a log that is too heavy? wind it up to a few different pressures just to test it's functioning. Ulimately it will need to be set a bit higher than the pressure needed to split the logs all else being equal.

With spools there are different configurations (open center/closed center) for e.g. which will give different operating characteristics, open center spools can allow A and B back to tank as well as P or just allow P back to tank in the center position, closed blocks off A and B with P returning back to tank or P returning via the pressure relief (power consuming

) and a few other configurations (if memory serves

) depending on what the application is.

Not sure which spool you have there but it doesn't look right, distances don't look right to give you flow from P to A (extend) or P to B (retract), I'll have another look at the pic, Is there some ID/markings on the spool that might indicate what it is when compared to the valve body, maybe a call to the valve OEM rather than the bloke that gave it to you???

Hope I haven't led you up the path too much, it has been a while

Pete

**Tankstand** · 17th July 2012, 07:45 AM

Are there any diagrams on the main valve and the relief valve? Please post pics if there are, they help a lot.

Thanks.

**West OZ Mark** · 20th July 2012, 03:30 PM

Thanks Pete and tankstand for the replies and yes Pete I found out by testing it that it is a one way valve between the Input in and Pressure valve. I did some more test on the controller but cant figure it out so reluctantly sent it back to get tested.

Thanks...Mark

**pjt** · 20th July 2012, 10:20 PM

OK Mark, let us know what they find out, my guess would be it's the wrong spool for the body

Pete

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