KX121-3 Hydraulic troubles

[Travis Lohnes]

Long time forum reader for knowledge and advice, newbie member. I have a Kubota Kx121-3 that has no hydraulic movement. The pilot pump is supplying pressure to valve block and I also have change valve pressure with safety lever down. Looking at the schematic I then checked pressure at bottom of valve bank of Pps and Pls and do not have any pressure at all. I can try to figure out how to post a schematic if anyone would like to have a look. I'm hoping for some advice before I take the machine somewhere to be diagnosed. If I don't have any pressure I assume either pump or unload valve or maybe a control valve is just dumping flow to tank.
FYI my uncle was last owner of this machine and this has happened a few times before I bought it but the problem has always just went away. It's been sitting for a while at my father in laws, went to float it home, started right up, got on trailer fine then when I got home to remove from trailer nothing would work... thanks for any input...

 

[Travis Lohnes]

P.S...I also have already removed unload valve spool as well as main control valve relief, inspected and cleaned, although I may have missed something..

 

[uffex]

Good day
According to my schematic we have a solenoid valve between the pump and distribution, have you a gauge to check if this is as it should be ?
Kind regards
Uffex

 

[uffex]

Oops should I mention if you have a pattern change valve check it is in position.

 

[Travis Lohnes]

Uffex, thanks for your reply.
The pattern change is in position. I checked with gauge and have PSI after the solenoid yes. I should mention even the dozer blade does not move as I believe this is not controlled by the solenoid.

 

[uffex]

Good day Travis
I not to sure where you have checked the pressure after the solenoid valve the feed line connects to the slew brake then returning to connect to the remote controls. Take a look at the attachment to be sure we are on the same page.
Kind regards
Uffex

 

[Travis Lohnes]

Hello, I had my gauge right into the outlet of the change valve. Where it leaves the solenoid and goes to the slew brake and the travel lock cylinder. Should I try to follow that line and test at more places?

 

[uffex]

Do you mean you have zero pressure at that point ? You should see about 40 bars 500 psi

 

[uffex]

If we simplify the schematic, maybe help. See attached

 

[Travis Lohnes]

Sorry, outlet of the change valve does have about 500 psi.

 

[uffex]

Ok we can discount the solenoid and pump but if I understand you correctly there is zero at the remote controls?

 

[Travis Lohnes]

The problem is nothing will move, dozer blade, tracks, boom etc. Some of these actions are controlled mechanically with a linkage.

 

[uffex]

Good day Travis
Your post has all the symptoms of a control lock out failure be it the solenoid valve, can you please hook a gauge into the line that runs to the swing brake and test for pressure.
Kind regards
Uffex

 

[Travis Lohnes]

Hey, the line that goes to swing brake comes from the "change valve" correct?

 

[uffex]

Hi Travis
Yes that is according to my schematic, may I suggest follow the output line from the small gear pump, it should go through a filter attach to an accumulator then to the solenoid valve. Mark the line at the solenoid, take a photo and post it. The slew brake has a number of lines, you can follow those back and note which goes into the solenoid valve.
Kind regards
Uffex

 

[uffex]

Hi Travis
I am sorry for the differences in industry terminology, manufacturers use university grads to write manuals all have a new interpretation of a common part "change valve" is also called "Lock" in the same document both of which mean "Control lock out" self-explanatory blocks the use of levers & pedals.
Sorry if this is confusing, a bug bear of the machines we work with. One day the industry will adopt common expressions helping all concerned.

 

[Travis Lohnes]

Uffex,
I understand what you are explaining. That solenoid has a tee, one line to the "travel lock cylinder" and one to the slew brake (which tees of again). I have 400-500 PSI at the valve where it tees to slew brake and to travel lock cylinder.

Thanks,
Travis

 

[uffex]

Good day Travis
Can you check to see if we have pilot pressure from the R.C.V. at the main valve stack, take one that is easy to get to, no matter if it boom bucket or arm.
Kind regards
Uffex

 

[Travis Lohnes]

I will check this later on today and report back.

Thank you for you're time.

 

[Travis Lohnes]

Looking at say the dozer blade valve, it is controlled by mechanical shuttle, not hydraulic pilot shuttle, if I have a pilot control issue shouldn't the dozer blade still work?