What can go wrong in a spool valve?

[ljplum12]

I've been having on-going problems with my FEL/spool valve. The lift function is not working. I disassembled the cylinders and the seals were shot, so I replaced them. I disassembled the spool for the lift function and didn't see any obstructions or anything that looked out of the ordinary. Initially I put a piece in backwards, but someone helped me track down the drawing for it from the manufacturer (Koyker) and I was able to determine the piece was in backwards and got it turned around. It still doesn't work. If I swap the lift hoses with the curl hoses on the spool valve, the lift works, but curl doesn't, which says to me my cylinders are fine now.

The only wear parts that I can see in the spool are o-rings at each end, but it seems to me that those would just keep oil in and not affect the operation of the valve.

I've contacted Koyker and am waiting for a response, but thought I'd get some additional opinions in the meantime.

 

[jabelding]

Lots of times loader valves have pilot operated check valves on the lift spool for safety. Not sure if your does but that can cause the lift not to work if they were taken apart and not put back correctly.

 

[ljplum12]

Where would that check valve be located?

Any idea what this piece is here?


Here it is removed.


I've attached the PDF of the mechanical drawing if that helps also.

 

[wdchyd]

load check valve

 

[boggen]

Where would that check valve be located?

Any idea what this piece is here?
View attachment 508466

Here it is removed.
View attachment 508467

I've attached the PDF of the mechanical drawing if that helps also.

steel balls = check valve. ball plugs up hole and once enough pressure from tractor is able to force ball away. to start pushing fluid towards the cylinders.

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also pressure relief valve = spring, if not set correctly fluid maybe by passing directly through relief valve. you need some gauges you can hook inline so you can actually adjust and set pressure relief.

hard to tell from diagram. there is a couple springs here and there to return lever/joystick back to center. that is not pressure relief. that is just centering / netural position springs.

 

[oldnslo]

If the lift function is working properly on the curl circuit then the system relief is operating correctly.

I did not see any P.O. checks in the parts diagram. Can you physically measure the spool travel on the lift valve and compare this to the curl valve. They should be very similar with the exception of going into float. If the spool movement is restricted this would not allow the lift function to operate correctly.

Not much else could cause this type of failure.

 

[ljplum12]

If the lift function is working properly on the curl circuit then the system relief is operating correctly.

Yes, I've also used a gauge to set the relief pressure right around 2100psi, so I have confidence that's working properly.

I did not see any P.O. checks in the parts diagram. Can you physically measure the spool travel on the lift valve and compare this to the curl valve. They should be very similar with the exception of going into float. If the spool movement is restricted this would not allow the lift function to operate correctly.

Not much else could cause this type of failure.

Yes, I can do that.

Based on the parts diagram, if that check valve were to not being working correctly, then the pressurized fluid would never reach the lift spool. Then when I actuated the spool, it would block the "bypass" path and build up as much pressure as the relief valve would allow.

Is that check valve supposed to be adjustable, or does it just screw all the way in?

If I were to remove the spring and poppet to test it out to I risk damaging anything?

 

[oldnslo]

Ljplum,
I believe the load check that you removed and show pictures of in post #5 is for the curl function. In looking at the parts break down I believe the load check for lift circuit is located directly beneath the relieve valve.

Attempted explanation of the Load check function:

In Open center systems the pump flow is allowed to flow freely to tank at a low pressure to illuminate heat build up and reduce power loss. A directional valve diverts flow based on how far it is moved in its bore. As an example a spool may travel 1/4" inch from center to full shift for raise. The first 1/16" is getting the spool through the spool overlap or dead band. The next 3/32" inch is the metering notches. This is where flow is starting to be directed towards the work ports and being restricted from slowly freely to tank. You have to move the spool far enough to restrict the flow enough to generate the pressure required to move the load. The load check prevents the load from falling during this transitional period. The rest of the spool stroke opens the path completely from the pressure ballet to the work port.

Unless the load check is jammed closed it would not prevent the loader from lifting.

If you have a gauge does the pressure rise when you shift the lift spool?

 

[ljplum12]

If you have a gauge does the pressure rise when you shift the lift spool?

Yes, I put a gauge on the pressure side of the valve, and when I shift the lift spool it goes up to whatever I have the pressure relief set to (right now around 2100psi).

In the diagram, curl is "3" and lift is "2". Is that how you are interpreting them?

 

[boggen]

if you are seeing pressure on the gauge when you operate the valve. the valve would be good.... i would say.

quick connects, if you have them between valve and cylinders, disconnect and then re-connect the quick connects, some times the quick connects do not seat properly when connecting them. (they got a ball check valve per say, and when you put them together, the ball does not get pushed correctly) not the best explanation. due to different types of quick connects out there and in how they seal off the oil and keep it from leaking out when disconnected. but still non the less... disconnect and reconnect the quick connects. (one of them try the very first things as trouble shooting steps) quick and easy.

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double checking... you did route the hoses correctly.... between both hyd cylinders on the FEL and bucket. and accidentally swapped one of them backwards. causing one cylinder to extend and another one to contract.