Kubota L3600/LA680 hydraulics problem. Need help

[houser52]

I wonder if one of the spools in the DValve or one of the QD's is fouled with some debris, sometimes even new hoses are filled with crap from when they cut them with an abrasive saw.

I hope it's some debris in one of the QDs. I don't know much about hydraulics but to me it sounds like if the bucket dump slows down during "fast dump", the relief valve sounds like it opens and the engine rpms drop, my thinking is the hydra fluid can't escape from the bucket cylinder as fast as its being pushed in. That's building up pressure in the cylinder to the point of the relief valve opening and the rpms dropping.

With that said, I thought I would replace the fluid return QD at the hydraulic block first. If it's restricted it would
slow down the fluid retuning to the tank.

Am I thinking about all this right or am I wrong?

 

[Leejohn]

In picture one what fittings are A2 and B2? I'm still missing something. Who is the mfg of the valve? I would like to see how the valve is ported.
To me the one he has marked A1 should be R1 and that goes to the rod end of grabber cyl. and the fitting right above it should be marked E1 I think but on the same spool. That should go to base end of grabber cyl.
The one marked B2 should be R2 and work as above but to the bucket.
Now I might be P****** in the wind, but thats the way I see it.

 

[houser52]

In picture one what fittings are A2 and B2? I'm still missing something. Who is the mfg of the valve? I would like to see how the valve is ported.
To me the one he has marked A1 should be R1 and that goes to the rod end of grabber cyl. and the fitting right above it should be marked E1 I think but on the same spool. That should go to base end of grabber cyl.
The one marked B2 should be R2 and work as above but to the bucket.
Now I might be P****** in the wind, but thats the way I see it.

This help any?

 

[Leejohn]

Yes and that is wrong the way I see it. Change A2 and B1 then it should work.

 

[houser52]

According to the instructions which came with the diverter, P1 and P2 flows directly to A1 and B1 and operates the bucket's curl and dump as if the diverter wasn't even there. When the diverter coil is energized by the button on the joystick, the fluid is routed to A2 and B2. That fluid path is what opens and closes the grapple.

The bucket curls as normal and the grapple opens/ closes as normal. The dump function works but there is a chatter/shudder at the beginning of the dump. The dump also slows down when moving the joystick to the fast dump position.

Everything had worked as it should for about an hour before the trouble started.

 

[Leejohn]

I.m not sure how the valve is ported and if the oil can cross over from one spool to the other then it should work as the instructions say.

 

[kennyd]

Yes and that is wrong the way I see it. Change A2 and B1 then it should work.

I.m not sure how the valve is ported and if the oil can cross over from one spool to the other then it should work as the instructions say.

Houser has it correct. The oils does not need to "cross over" from one spool to the other.

A1 and B1 is the default circuit when the coils are NOT powered.
A2 and B2 is the diverted circuit when the spools are powered.

 

[Leejohn]

Yes I finaly understand how it works and I was way out in left field.

 

[houser52]

I hope it's some debris in one of the QDs. I don't know much about hydraulics but to me it sounds like if the bucket dump slows down during "fast dump", the relief valve sounds like it opens and the engine rpms drop, my thinking is the hydra fluid can't escape from the bucket cylinder as fast as its being pushed in. That's building up pressure in the cylinder to the point of the relief valve opening and the rpms dropping.

With that said, I thought I would replace the fluid return QD at the hydraulic block first. If it's restricted it would
slow down the fluid retuning to the tank.

Am I thinking about all this right or am I wrong?

kenny- I received the couplers this morning. Thanks for the fast shipping.

Please see my theory above about where to begin to look for a restriction. I wanted to see if you think I'm starting at the right place by replacing the 2 couplers in the return lines first. According to the diagram the couplers are the ones going to ports "C" and "D". Both of those look to be return lines.

Thanks

 

[kennyd]

kenny- I received the couplers this morning. Thanks for the fast shipping.

Please see my theory above about where to begin to look for a restriction. I wanted to see if you think I'm starting at the right place by replacing the 2 couplers in the return lines first. According to the diagram the couplers are the ones going to ports "C" and "D". Both of those look to be return lines.

Thanks

Well, these are the "main" feed and return lines to the entire valve, so if there was a problem with those then you would be experiencing trouble on every function, follow me?

Since you are only having trouble with one function-the dump (joystick right), I think you need to concentrate on the QD's and connections there first. You can also easily unscrew the spool from the diverter block and look for debris in there also.

Does that make sense?