Kubota KX71-2 hydraulics

[philt]

Hello,
I have a problem with my kx71 - the machine slew works fine but a few weeks back the boom swing stopped working.
Not a major issue but earlier this week it developed a hydraulic leak.While sorting the leak (loose pipe connection) I thought I would have a look at the boom swing function. As far as I could see there is a solenoid operated directional valve which operates to switch from machine slew to boom swing (push button on LH control lever). Checked this with a meter - getting 12v when button is selected. I then removed the solenoid valve and cleaned it then refitted. Machine slew still working in both directions, but now when button operated for boom slew the boom swings to the right (when right selected) but the machine slews to the left (when left selected). I now think I have a problem with the main control valve block but am a bit reluctant to go any further without more info. Does anyone have a diagram of the valve block identifying each part or a hydraulic drawing for my machine? I have downloaded a workshop manual for the kx71-3 but the valve block is different.

Cheers,
Phil.

[Muz]

Hello,
I have a problem with my kx71 - the machine slew works fine but a few weeks back the boom swing stopped working.
Not a major issue but earlier this week it developed a hydraulic leak.While sorting the leak (loose pipe connection) I thought I would have a look at the boom swing function. As far as I could see there is a solenoid operated directional valve which operates to switch from machine slew to boom swing (push button on LH control lever). Checked this with a meter - getting 12v when button is selected. I then removed the solenoid valve and cleaned it then refitted. Machine slew still working in both directions, but now when button operated for boom slew the boom swings to the right (when right selected) but the machine slews to the left (when left selected). I now think I have a problem with the main control valve block but am a bit reluctant to go any further without more info. Does anyone have a diagram of the valve block identifying each part or a hydraulic drawing for my machine? I have downloaded a workshop manual for the kx71-3 but the valve block is different.

Cheers,
Phil.

Welcome to the forum Phil .. I'll have a look at my old manuals .. is it a solenoid that slides over a pole? I cant remember ... can we see a pic ?.. all it does is pull on a spool, so if its not pulling it on fully it will give some strange effects I think. The pole mounted ones in particular need to be properly seated, otherwise they wont pull the service fully.

[philt]

Hi Muz,
Thanks for the prompt reply - I think the solenoid valve must now be working ok as the boom swing is working, even though only one direction. I have traced the pipes from the sol valve to the control block and I think that's how it switches function. I have pics of the valve block and solenoid valves but I think I need to "host" them before I can attach them. Will try to sort later tonight.
Cheers,
Phil.

[philt]

This shows the solenoid valve



This is the main valve block
2nd block from left is machine slew
4th " " " " boom swing

[philt]

That went well...............
Pics work if copy url into new window.

[Stock]

I find photobucket less trouble sometimes............

[philt]

Just had a thought regarding the two solenoid valves (shown in 1st pic) - I assumed that the second valve was for the two speed tracking (which doesn't work either) but did not see any volts when pressing the foot switch to select high speed tracking.Is it possible that one sol valve selects boom swing in one direction and the second in the other direction?I did not check for volts on the 2nd solenoid when boom swing was selected - this would confirm the theory. I will also trace out the pipework from the 2nd solenoid when I get chance.
Oh for a hydraulic drawing.................
Any thoughts appreciated,
Phil.

[Stock]

Talk nice to Muz promise him some native beverage and well you never know You might prove the Scottish myth wrong......

[Muz]

right let me sort this .. Stock .. your pics are from a dash 2 which is different .. the op cant post pics cos hes in the new members group .. Ill sort that now

*edit* philt youve made over 5 posts so you were upgraded automajically pics wont be a problem now

[Stock]

right let me sort this .. Stock .. your pics are from a dash 2 which is different .. the op cant post pics cos hes in the new members group .. Ill sort that now

*edit* philt youve made over 5 posts so you were upgraded automajically pics wont be a problem now

Not my pix Muz I lifted them from Phil Flicker page..............

[Muz]

Not my pix Muz I lifted them from Phil Flicker page..............

Ahh I see now thanks for that .. ok I'll have a look for a dash 2 manual

Begging your pardon the op said it was a dash 2 .. sorry .. they did go a bit weird on this series .

Lots of folk said high vibration environments wernt a good mix for new electronics .. but even Kubota didnt listen

[ianoz]

Ahh I see now thanks for that .. ok I'll have a look for a dash 2 manual

Begging your pardon the op said it was a dash 2 .. sorry .. they did go a bit weird on this series .

Lots of folk said high vibration environments wernt a good mix for new electronics .. but even Kubota didnt listen

Think what confused you Muz ,was he said he downloaded a dash 3 manual .

[philt]

Quick update on the boom swing fault - I checked the supply to the 2nd solenoid valve (shown in 1st pic) and it was switching as per 1st solenoid from button on LH control lever. Removed the valve (it was stuck) freed it off and refitted.I now have boom swing in both directions - happy days!
So, it looks like 1st sol valve switches for boom swing to the right, 2nd sol valve switches for boom swing to the left.Seems strange that both spools jammed at the same time, but all appears ok at the mo.I have put together a word document detailing what I have learned so if anyone else has a KX71-2 I can forward a copy if req. I also have the Kubota WSM for the KX71-3 if anyone needs any info.
Cheers,
Phil.

[Muz]

Quick update on the boom swing fault - I checked the supply to the 2nd solenoid valve (shown in 1st pic) and it was switching as per 1st solenoid from button on LH control lever. Removed the valve (it was stuck) freed it off and refitted.I now have boom swing in both directions - happy days!
So, it looks like 1st sol valve switches for boom swing to the right, 2nd sol valve switches for boom swing to the left.Seems strange that both spools jammed at the same time, but all appears ok at the mo.I have put together a word document detailing what I have learned so if anyone else has a KX71-2 I can forward a copy if req. I also have the Kubota WSM for the KX71-3 if anyone needs any info.
Cheers,
Phil.

Good to know you got it sorted You could always just post your findings here, as thats what we all do for everyones benefit should be able to copy and paste it

[Muz]

Philt has kindly made a resume of his findings and made a word document that couldnt readily be transposed with pictures to the forum, (because of photo ownership issues and copyright) so I have done that so you can see what he has found ...

for the record guys, do your scripts elsewhere for sure, as is best to edit what you want to say off the forum if its an article you want to make .. have the pics on stand by in a separate folder, then merge them together on the forum post page





Kubota KX71-2 Hydraulics.

What follows is a brief description of a fault I encountered on my Kubota and what I did to fix it, along with some observations, and suggestions regarding valve function. This was done without the use of a workshop manual so cannot guarantee accuracy 100%.
It will hopefully be some use to anyone who develops a similar fault.

Motions:

1. LH Track Motor (Man)
2. RH Track Motor (Man)
3. Slew Motor (Pilot valve)
4. Breaker (Man-Not used)
5. Blade raise/lower (Man)
6. Boom swing (Pilot valve)
7. Boom raise/lower (Pilot valve)
8. Dipper arm raise/lower (Pilot valve)
9. Bucket crowd/dump (Pilot valve)

pic1.jpgpic2.jpgpic3.jpg






Hydraulic Valve Block Function (Left => Right)

1. Pressure in + relief with test point
2. Machine slew (pilot operated)
3. Blade raise/lower (manual)
4. Boom slew (pilot operated)
5.
6. Spare spool (manual)
7.
8. Dipper arm raise/lower (pilot operated)
9. Two speed tracking???? (pilot operated)
10. LH track motor (manual)
11. Two pressure inlets with test points
12. RH track motor (manual)
13. Boom cylinder (pilot operated)
14. “ “ “ “
15.
16.


pic4.jpg




pic5.jpg

Solenoid operated directional valves x2 :ZEXEL 307804-1380
Selects either machine slew OR boom swing.

The two solenoid operated directional valves are shown in pic above. Both valves are energised by the boom swing select button on LH control lever. First valve (nearest in pic) controls pilot supply for swing right, second valve controls pilot supply for swing left. The initial fault was loss of swing motion in both directions, with either swing or slew selected. I removed and cleaned the first solenoid valve and after re-fitting it would swing the boom to the right, but slew the machine to the left. Removed and cleaned the second solenoid valve, then able to swing boom in both directions as normal.
pic6.jpg

Hydraulic system split into three sections:
1 Front
2 Swivel
3 Travel

The RH & LH control levers operate the pilot valve directly – NO electrical servo valves.
Pb on LH lever switches between machine slew & boom swing.
Pb on RH “ operates horn.