KX057-5 front blade hyd. not strong enough

[iafarmerken]

I am having trouble with my KX057-5 front blade not holding pressure while digging. It doesn't take very much lifting force with the bucket to push the blade up therefore losing the stability that it is supposed to add. Is there a pressure relief valve that needs adjusted? Seem to work fine when i first got it. Thanks all.

 

[GreensvilleJay]

Had to lookup what it is...
I consider excavator blades to be 'leveling' blades not 'digging' like a loader can. They're more for pushing material. Used friend Kx-041(?) for years..it's a pusher NOT a digger.
I need to ask what kind of material is it and temperature ? Have you adjusted the blade angle ?

 

[TheOldHokie]

I am having trouble with my KX057-5 front blade not holding pressure while digging. It doesn't take very much lifting force with the bucket to push the blade up therefore losing the stability that it is supposed to add. Is there a pressure relief valve that needs adjusted? Seem to work fine when i first got it. Thanks all.

First guess would be leaking spool in control valve. How long will it hold the front up with bucket off the ground and nothing else going on?

Dan

 

[SDT]

Had to lookup what it is...
I consider excavator blades to be 'leveling' blades not 'digging' like a loader can. They're more for pushing material. Used friend Kx-041(?) for years..it's a pusher NOT a digger.
I need to ask what kind of material is it and temperature ? Have you adjusted the blade angle ?

Agreed.

Most likely intended for loose materials as is my Kubota snow/loose materials front blade.

SDT

 

[TheOldHokie]

Agreed.

Most likely intended for loose materials as is my Kubota snow/loose materials front blade.

SDT

He is digging with the excavator bucket and using the front dozing blade as a stabilizer. Pretty standard operation.

Dan

 

[North Idaho Wolfman]

Sounds like an internal bypass (seal leak) on the cylinder / cylinders.

 

[TheOldHokie]

Sounds like an internal bypass (seal leak) on the cylinder / cylinders.

Not in the retract direction unless there is a port relief on the valve. We covered this at some length a few weeks ago.

How To Troubleshoot Hydraulic Cylinder Drift

A popular misconception about hydraulic cylinders is that if the piston seal is leaking, the cylinder will drift down. Fact is, if the piston seal is completely removed from a...

www.powermotiontech.com

Dan

 

[North Idaho Wolfman]

Not in the retract direction unless there is a port relief on the valve. We covered this at some length a few weeks ago.

How To Troubleshoot Hydraulic Cylinder Drift

A popular misconception about hydraulic cylinders is that if the piston seal is leaking, the cylinder will drift down. Fact is, if the piston seal is completely removed from a...

www.powermotiontech.com

Dan

I said Internal leak.

 

[Jchonline]

Had to lookup what it is...
I consider excavator blades to be 'leveling' blades not 'digging' like a loader can. They're more for pushing material. Used friend Kx-041(?) for years..it's a pusher NOT a digger.
I need to ask what kind of material is it and temperature ? Have you adjusted the blade angle ?

Wrong. The excavator blades on this size machine can absolutely be used to level the machine, and provide counter force for lifting or digging with boom/arm fully extended. There is most likely an issue with the OPs blade hydraulic function.

 

[dirtydeed]

Ken(?), I don't have an answer for you...only a question. Are you typically digging over the blade or are you using it in the rear for "pinning"?

I've found that if I dig with the blade to the front (KX033), it will lose its perch after a little while. I don't have the same issue when it's behind me in the pinning position. Likely because it wouldn't be holding up as much weight as if it were in front.

I also like the blade to rear for visibility. The angle blade on these things stick out further away from the machine than fixed blade machines. That really limits what I can see down in the hole/trench.

Following this thread to see if you can get it resolved.

 

[TheOldHokie]

I said Internal leak.

View attachment 75091

That would be an external leak. Parts breakdown does not show a port relief on that section.

Dan

 

[North Idaho Wolfman]

That would be an external leak. Parts breakdown does not show a port relief on that section.

Dan

So your saying that an internal seal leak can not cause a cylinder to loose lift pressure?

 

[TheOldHokie]

So your saying that an internal seal leak can not cause a cylinder to loose lift pressure?

I am not sure how to answer that. Lets try this:

A piston seal leak can/will reduce the effective working area of the cylinder. It will become the cross sectional area of the rod and that will result in a loss of lifting force. If the leak is slow and the cylinder lifts normally the cylinder pressure will climb as the cylinder holds and the pressures equalize across the leaking seal. This is the point at which a port relief comes into play.

Dan

 

[North Idaho Wolfman]

If any of the internal seals leaks then the fluid from one side of a cylinder will move to the other side of a cylinder making the lift force drop, thus the cylinder drifts off.
So if you lift the Excavator with the blade and the excavator drops back down, it most certainly can have a blow internal seal.
Yes it could also have a leaking spool valve, but that is much less likely, especially with a newer unit.

 

[TheOldHokie]

If any of the internal seals leaks then the fluid from one side of a cylinder will move to the other side of a cylinder making the lift force drop, thus the cylinder drifts off.
So if you lift the Excavator with the blade and the excavator drops back down, it most certainly can have a blow internal seal.
Yes it could also have a leaking spool valve, but that is much less likely, especially with a newer unit.

The rod CANNOT drift inwards. That would reduce the volume of oil in the cylinder and there is no place for that excess oil to go. So forget oil moving from one side to the other - can't happen.

The rod stays locked in place and the oil pressure on the base end builds to reflect the loss in effective piston working area. The base and rod end pressures ultimately equalizes at an increased level which is now working over a smaller area and equal to the force the cylinder is holding. Read the entirety of the article I linked.

Dan

 

[iafarmerken]

Thanks for the replies. I am using the front blade for stabilization and extra leverage when digging stumps. This is normal procedure on these units with front blades. It looses pressure on the blade when the machine rocks forward from digging pressure. It didn't do this when it was brand new (only has 80 hrs now). I just got off the phone with the dealer and they suggested that trace the blade hyd line back and find the pressure relief valve. It may have something stuck in it. I would just haul it to them but I'm a couple hours away. I appreciate all the help and will report back my findings.

 

[TheOldHokie]

Thanks for the replies. I am using the front blade for stabilization and extra leverage when digging stumps. This is normal procedure on these units with front blades. It looses pressure on the blade when the machine rocks forward from digging pressure. It didn't do this when it was brand new (only has 80 hrs now). I just got off the phone with the dealer and they suggested that trace the blade hyd line back and find the pressure relief valve. It may have something stuck in it. I would just haul it to them but I'm a couple hours away. I appreciate all the help and will report back my findings.

So there is a port relief in the lines feeding the cylinder? With only 80 hours on the machine that sounds like a very good possibility.

Dan

 

[iafarmerken]

Ken(?), I don't have an answer for you...only a question. Are you typically digging over the blade or are you using it in the rear for "pinning"?

I've found that if I dig with the blade to the front (KX033), it will lose its perch after a little while. I don't have the same issue when it's behind me in the pinning position. Likely because it wouldn't be holding up as much weight as if it were in front.

I also like the blade to rear for visibility. The angle blade on these things stick out further away from the machine than fixed blade machines. That really limits what I can see down in the hole/trench.

Following this thread to see if you can get it resolved.

I am digging over the blade for extra lifting leverage. If i lift the machine all the way up in the air with the blade it will come down all in one stoke of the boom with a load.


I agree about the visibility but for stumping i need the leverage up front. It was able to hold the machine stable a month ago.

Thank You for the help.

 

[GreensvilleJay]

ok...' I am using the front blade for stabilization and extra leverage when digging stumps' sounds normal use to me,I took the original post to mean you using it like a bulldozer blade and 'digging' the ground.
Sounds like 'something', aka 'foreign matter' is allowing the oil to flow when it shouldn't. Doesn't take but a 'speck' to cause this kind of grief.

 

[Henro]

If any of the internal seals leaks then the fluid from one side of a cylinder will move to the other side of a cylinder making the lift force drop, thus the cylinder drifts off.
So if you lift the Excavator with the blade and the excavator drops back down, it most certainly can have a blow internal seal.
Yes it could also have a leaking spool valve, but that is much less likely, especially with a newer unit.

I have the same issue with my old excavator. I understand what Dan is saying. Think about it.

If you have a hydraulic cylinder and fully extend it by pushing oil in the cylinder, and then cap the two ports on the cylinder, and if the seal at the cylinder rod functions normally, so no oil leaks out, then if the cylinder rod went into the cylinder, the volume inside the cylinder would decrease.

So where would that oil go? Nowhere, since it cannot leak out of the cylinder. So the cylinder rod will never enter the cylinder unless there is someplace for the oil inside the cylinder to go.

So unless there is a leakage path outside the cylinder when the cylinder for the blade is fully extended, the blade will not move.

With my high hour little mini ex I am going to install a pilot operated check valve on the cylinder. I do not want to spend the time or money to make things factory original. Just want my blade to stay down while using the excavator, without having to keep manually pushing it down every few minutes.