Side supports and log turner are automatically rising

[MobileSawMilSlo]

Hi

On LT35 hydraulic, side supports and log turner are automatically rising when the hydraulic motor is idle and I am cutting logs. They are rising approx. 2 inches per minute and this gives me problems when I need to cut last board. At the middle of the cut, the side supports are so high that I can hit them and destroy the blade.

Did anyone have this experience and how did you solve it?

I was thinking ... this can be related maybe with valve leakage?
Should I replace rubber seals inside?

Thx for any suggestions.

[Magicman]

You will need to have a seal kit installed in the hydraulic cylinder (s). 

[Remle]

I'm with the OP on this one, valve leakage.

[MobileSawMilSlo]

Today I have done one test about this issue.
I switched hoses from the valve which operates with side supports and log turner to another valve (for lifting the log).

The problem remains the same, so this is not the issue with the valve as we were talking.

What I have found out is that the side supports will not automatically raise if the log turner is not activated.
Due to the fact that side supports and log turner are connected with an inline relief valve put on each cylinder (one pcs on cylinder for side supports and another pcs on cylinder for log turner), something is happening here.

This is the inline relief valve I am talking about: https://vonberg.com/products/view/48

[Magicman]

See Reply #1 above. 

That valve simple allows the side supports to fully raise before diverting fluid to the log turner.

[fluidpowerpro]

Although not on an LT35, I seen it before where if there is a restriction in the tank line, depending on the center condition of the directional valve, the back pressure will cause a cylinder to extend when you wouldnt expect it. 
If a cylinder has equal pressure on both rod and cap end, it will extend because the cap end has more area. 

[Crossroads]

You will need to have a seal kit installed in the hydraulic cylinder (s).

Lynn, do you have a suggestion which cylinder to start with? My thought would be the log turner since it does more heavy lifting. Although, my side supports get used for standing up flitches and reverse rolling cants. So, it wouldn't surprise me if I blew a seal on that cylinder. 

[Magicman]

The side supports and claw are plumbed so that the side supports have to be fully upright before hydraulic fluid is allowed to flow to the claw through these.  If I remember correctly....


 

If the side support cylinder leaks back, the back pressure should flow through the above pictured valve and slightly expand the turner hydraulic cylinder and raise the turner claw.

I would rebuild the side support cylinder first, but since all of the cylinders are the same age, I expect that you will soon rebuild it.