l4200 3PH stumped…..

[greagin]

Ok, I have a 1999 L4200 that runs like a top……BUT recently my 3PH has started acting strangely. The position control lever, when actuated, doesn’t show any lift of the implement until about position 5-6??? Then it will jump up to full lift by position 8, but as you can see that doesn’t leave much room for sensitivity or forgiveness. I looked at adjustment and everything is free and moving. I only Run super UDT, it has plenty of fluid and just changed the hydraulic filter with oem kubota. The valve open and close works fine I can totally stop the hydraulic by closing and totally open by opening. Very
Frustrated as to what this might be. Any thoughts? Suggestions? Ideas??

 

[Dave_eng]

The first place to start is to look for a bent or disconnected feedback rod.
This link advises your 3 pt system where (at what height) the arms are at.

Dave

 

[greagin]

To further clarify, it’s like there’s a few inches of play in the position control lever before anything happens…

 

[greagin]

All is good with feedback rod. All connections good, no obstructions. That’s what’s leading me towards bad control valve? Or would it be a bad regulator valve? I just don’t know how the whole system is Interconnected and all the drawings are separate. I hate to just throw money at it but I’m about ready to start

 

[greagin]

thank you for the reference, I will go through that sequence tomorrow am and report back! I hope that will
Help and it’s just out of adjustment!

 

[greagin]

Update:

following above procedure, but when I get to step 9, the relief valve is still operational. Is the the sign of a bad valve?

 

[TheOldHokie]

Update:

following above procedure, but when I get to step 9, the relief valve is still operational. Is the the sign of a bad valve?

Much more likely you got the setting wrong in Step 6. By the time you finish Step 6 the relief valve should be closed at the full up position.

Dan

 

[greagin]

Yes it will close per se at full up, but no matter what when I lower the control lever the lift arms fall as well. I even market it with a sharpie to be able to tell the exact moment when the relief valve was operational.

 

[greagin]

Just for kicks I ran the threads all the way in clockwise on the feedback rod and even then the lift arms still lower when I move the lever down to the lowest position.

 

[greagin]

So is that the control valve on the schematic? Are they rebuildable or is it best to get a new one?

 

[TheOldHokie]

Just for kicks I ran the threads all the way in clockwise on the feedback rod and even then the lift arms still lower when I move the lever down to the lowest position.

What do you think it should do? Lever down lowers the lift.

Dan

 

[greagin]

Read the above protocol for adjusting the feedback rod. At step 6 you set the throttle to max RPM and run the lever to full up and full down making sure the relief valve does not operate. It should be fully closed at this point and not move anything up or down is my understanding of the instruction. Mine will not fully close thus I would presume that there is a plunger or something not fully seating in the valve itself. No?

 

[TheOldHokie]

Read the above protocol for adjusting the feedback rod. At step 6 you set the throttle to max RPM and run the lever to full up and full down making sure the relief valve does not operate. It should be fully closed at this point and not move anything up or down is my understanding of the instruction. Mine will not fully close thus I would presume that there is a plunger or something not fully seating in the valve itself. No?

I think you are confused. The lift is going to move up and down which is the correct behavior. If it did not something would be very wrong.

The relief valve is inside the rear housing - not sure how one would determine its open/closed state.

Dan

 

[greagin]

Maybe so, but by my read it states that at that position the relief valve would be closed and not allow any bypass. Read step 9. It states to set throttle at max and then move the lever to upper most and lower most to make sure that relief valve doesn’t operate. Mine will never achieve that state. Maybe Dave can clarify? Seems pretty straightforward and with the way mine operates when doing this procedure seems to support my observation of a bad control valve. Now, I hope I am confused as a new valve is $880 it looks like!! Geez!

 

[greagin]

By this procedure it would seem that open is allowing bypass or downward movement and closed is the opposite, no bypass and totally locked out in uppermost position??

grant

 

[TheOldHokie]

Maybe so, but by my read it states that at that position the relief valve would be closed and not allow any bypass. Read step 9. It states to set throttle at max and then move the lever to upper most and lower most to make sure that relief valve doesn’t operate. Mine will never achieve that state. Maybe Dave can clarify? Seems pretty straightforward and with the way mine operates when doing this procedure seems to support my observation of a bad control valve. Now, I hope I am confused as a new valve is $880 it looks like!! Geez!

You going to argue with Dave too?

I will simply say your analysis of how position control and the relief valve work is not even close. Feel free to spend a lot of money and learn the hard and expensive way.

Dan

 

[greagin]

First off Dan, i am not arguing, i am trying to understand.

Second, what’s your opinion of the procedure sir? have you ever done it? Can you help me with it?

Please help me, I’m trying to understand, So what am I missing? I followed the procedure step by step. When you get to the part about backing the nuts off together until you see operation of the relief valve, what you will see (yes, i have seen this) are the lift arms lowering or the relief valve operating……

At that point of operation it says that you then turn the nuts together clockwise 2 turns. This should hold the lift arms in the uppermost position. This is my understanding of what you are checking when it then states to move the lever up and down a few times to make sure the relief valve does not operate.

At that point you measure the free play travel in the lift arm by manually Lifting the arm all the way up and checking to see if it’s in spec just like the picture shows. So what am I missing? I definitely don’t want to spend copious amounts of money if I don’t have to.

 

[TheOldHokie]

First off Dan, i am not arguing, i am trying to understand.

Second, what’s your opinion of the procedure sir? have you ever done it? Can you help me with it?

Please help me, I’m trying to understand, So what am I missing? I followed the procedure step by step. When you get to the part about backing the nuts off together until you see operation of the relief valve, what you will see (yes, i have seen this) are the lift arms lowering or the relief valve operating……

At that point of operation it says that you then turn the nuts together clockwise 2 turns. This should hold the lift arms in the uppermost position. This is my understanding of what you are checking when it then states to move the lever up and down a few times to make sure the relief valve does not operate.

At that point you measure the free play travel in the lift arm by manually Lifting the arm all the way up and checking to see if it’s in spec just like the picture shows. So what am I missing? I definitely don’t want to spend copious amounts of money if I don’t have to.

I have not followed that procedure but I have adjusted the feedback linkage many times.

1. The relief valve OPENS when the lift arms are at the limit of their upward travel and the position control valve is still calling for lift. The lift is jammed at full up and the excess flow from the pump is going to tank via the relief valve.
2. At step 6 in the manual description the relief valve is OPEN unloading pump pressure because the POSTION control valve is CLOSED calling for lift
3. Adjusting the nuts causes the feedback linkage to kick the POSITION control valve in to NEUTRAL. That allows the pump to unload to sump,
4. With the position control valve in NEUTRAL the RELIEF valve can close because it is no longer unloading the pump. The lift DOES NOT change position - it holds where it is. This is teh desired adjustment point described in #6 of the procedure.
5. If you keep on turning the nuts the max lift set point will be reduced.
6. That causes the feedback linkage to kick the position control valve into the LOWER position and the lift arms will drop just slightly before the linkage movement again causes the position control valve to go back to NEUTRAL and teh lift arms hold at the new set point.

The proper full up adjustment is obtained somewhere between steps 4 and 5 above. Once that is set you can position the lift at any intermediate point by moving the position control lever up or down as appropriate.

Now would you like me to explain what was happening with your initial complaint?

Dan

 

[greagin]

Yes yes I follow you, thank you for helping me!! This is very helpful. So when it says to turn the nuts counter clockwise to the point of relief valve operation, what should I be looking for? The only thing I saw, or I’m aware that I saw were the lift arms starting to lower. The process seemed straightforward but now I feel like I am completely lost in this process.

and yes please help me with the initital
Complaint! I swear the tractor did not used to do that and this has all of a sudden started but I have no idea what direction to go to resolve!

 

[TheOldHokie]

Yes yes I follow you, thank you for helping me!! This is very helpful. So when it says to turn the nuts counter clockwise to the point of relief valve operation, what should I be looking for? The only thing I saw, or I’m aware that I saw were the lift arms starting to lower. The process seemed straightforward but now I feel like I am completely lost in this process.[

and yes please help me with the initital
Complaint! I swear the tractor did not used to do that and this has all of a sudden started but I have no idea what direction to go to resolve!

When you get to the point where turning the nuts cause the lift arms to sag ever so slightly that is your set point. Stop adjusting and lock it down.

Now as to your initial issue. The hitch point on many implements is well above the full down height of the lift arms. To hook up you manually LIFT the arms UP to connect them to the lift pins. That is using up some of the single acting hydraulic lift travel and it is lost, With teh implement attached the arms can never go all of the way down when you move the position control to the full down position. Consequently, as you begin to move the control lever back upwards the lift cylinder is actually extending but is not in contact with the rockshaft. Externally that looks like the lift is not doing anything but it really is. Once the cylinder gets moved far enough it contacts the rockshaft and you begin to see movement at the implement.

In other words - the higher the lift pins are on the implement the more free play you will have at the bottom of the position control lever travel. My mower sits really low and it picks up very low on teh position control quadrant. My log splitter is much taller and it it does not start to lift until very near the top.

Dan