Kubota KX36-3 - Arm not functioning while traveling.

[JTP]

Hi All,
Looking for a bit of advice please?

When traveling, the whole arm Assy won't lift or function at all until I stop the travel and then the hydraulics will kick in and the arm will function properly.
I have no leaks that I can see and have replaced the main hydraulic piston pump which did not help.

Is there a valve somewhere that could be sticking and causing this problem?

Not sure where to start looking so any help or advice would be appreciated.

Thanks and regards,

JTP

 

[doobin]

Might well be normal.

 

[JTP]

It used to work before, when going down a slope I used the arm and bucket to balance the digger if it was steep and it functioned then, it started to slow down over the last few months but now won't work at all.

 

[Mogman]

Sounds like lack of servo pressure if on joy sticks

 

[JTP]

Ok, so how would I be able to check that out, where are the servos and what powers them.

Sorry for the question's

 

[diggerjones]

Pretty sure that might be normal as said above.
I've got a kx36-2 and i think you have to feather the levers if you want to do as you say

 

[V8Druid]

Ok, so how would I be able to check that out, where are the servos and what powers them.

Sorry for the question's

servo circuits usually function at a much lower pressure than the main circuits (usually 30-35Bar) and provide the pressure/(power) to the sticks to open the main circuit pressure valves to make the motions function. (Basically an oil/pressure linkage to move the valve's spools, instead of a mechanical actuator link/rod)
On larger machines they usually have their own servo pump producing the required pressures to operate the servo circuit and no more. Smaller machines often have the servo pressure 'bled off ' the main pump's supply and reduced to servo working pressure by a dedicated valve assembly. Usually a servo circuit return filter in the system somewhere .. possibly in the reducer valve block. Might possibly be choked and when demanding the main pumps full flow for tracking, might not be enough left to overcome a choked filter? ... it would fit with the gradual loss over a period of time ... once the full pump flow returns, it has sufficient to over come said choke .. might reach a point where it won't work at all eventually??

 

[JTP]

Hi V8Druid, thank you very much for that info, that makes sense.

I will do a bit more investigation now you have given me a direction to look.
Now it's time to try and find the service manual on the web...

Much appreciated.

 

[Mick-the-fitter]

Kx36 - 2 has gear pumps (only variable by speed) Kx36 - 3 has variable flow swash plate pump (variable by load) the pilot pump oil is used to operate the piston that moves the plate in the main pump. The piston pump is able to run in a neutral, no oil position.