Yuchai Dozer with Backhoe: backhoe hydraulic issue

[Darvish]

I just wrote this question, and then deleted the post, instead of posting it.

^&(^&&^%


(^^Been a good tool: particularly when I get the turf-tired Kubota stuck...)



So anyway, I think the overpressure relief valve in the backhoe supply tank tank is stuck open, or the spring broke...

Is it a big deal or a little deal to fix this?

Wish I had a service manual..

 

[Bob Rooks]

Is this a LW-6 or JW-03 backhoe?
Btw, to my knowledge none of the Chinese manufacturers offer a service manual.

 

[Dave M7040]

Lets start with a description of the backhoe hydraulics. Does it have its own pump and reservoir or is it fed from the dozer?

Any relief valve will be in the control valve not the reservoir.

What are the symptoms you are experiencing?

Dave M7040

 

[Bob Rooks]

I will acquiesce to Dave M7040.

 

[Darvish]

Is this a LW-6 or JW-03 backhoe?
Btw, to my knowledge none of the Chinese manufacturers offer a service manual.

and a quote from Dave:

"Lets start with a description of the backhoe hydraulics. Does it have its own pump and reservoir or is it fed from the dozer?

Any relief valve will be in the control valve not the reservoir.

What are the symptoms you are experiencing?

Dave M7040"

=======================

The bh is the LW 6 model.

It has a pto pump driving it, it's own reservoir.


And (lightbulbs go off!!!) here's a picture of (tada...)


the control valves including the elusive PRESSURE RELIEF VALVE!!

Thank you for the guidance, these "user affinity groups" are of GREAT VALUE,
and "value" comes from willingness to help others.

In my search for images to illustrate the answer to your questions,
the first and primary question of "Where is the durn thing" became clear.

=================================

An example of the problem would be:

Presume the angle of the floor is not quite horizontal,
that you are on a slope, directly uphill from the place you are digging from.

You pick up a light bucket of sand, and sweep over to the left, to the limit of travel, to dump the sand.
As you begin to uncurl the bucket, the boom and arm of their own accord drift back "downhill",

I mean, that's a fairly insignificant load.

And when digging, if the bucket has a good load, you can't lift it.

And the sound of sibilant sssssssqueaking of fluid thru a valve is heard.

=====================================

So?

Think it's a broken spring, or stuck valve, or?? What's next??

Thank you ..

 

[Darvish]

So, what do i do?
Left to my own devices, I would disassemble the valve by removing the adjustment cap,
and see if the (presumed) seal has any blocking "junk",
or if the spring has broken, or whatever.

I'll endeavor to keep track of the "loading" on the relief valve,
but I can see this leading to the necessity of a pressure gauge for hydraulic systems,
one of which I am currently not possessing...

Any advice or should I just dive in?
(after I've got the steering linkage adjusted, which will take most of the day,I 'spect.)

 

[ericm979]

I think the larger black "relief valve" on the inlet is the relief valve and the smaller one on the right most valve in the pic is for the extra spool travel for the boom's float position.

 

[Darvish]

I think the larger black "relief valve" on the inlet is the relief valve and the smaller one on the right most valve in the pic is for the extra spool travel for the boom's float position.

Thank you.

I've found a couple of threads here that talk about miscellaneous garbage, rats, metal chips, etc. in Chinese pressure relief valves.
Well, the rats may be an exaggeration, but the chips surmission may apply.

If I take it apart, will I have to chase down a hydraulic pressure gauge to safely reinstall it,
or??


see
https://www.tractorbynet.com/forums/hydraulics/369007-chinese-backhoe-hydraulic-pressure-issue.html

for one of the "chips" reference.

 

[Darvish]

This post will brand me as a bloomin' jackass, and I'm whipping myself with my right hand while typing with my left.

Having a need to disconnect the backhoe, and needing some quick disconnects,
I decided to put the PTO in neutral to see if I could get by with some low pressure anti-dirt measures in the meantime.

May gawd have mercy on my mizzable soul, imagine my surprise to note that the freakin' thing was already in neutral.
I'm amazed it worked at all in neutral, please don't banish my stupid dumb-*** selfness..

(sob...)

(Where's the best place for hydraulic disconnects that fit these chinese fittings??)

Signed,
Stoopid MF,
me

 

[Bob Rooks]

Did you know you have two PTO's? An upper, which is live, and always engaged, and a lower which has the 1-3/8" splined shaft and is controlled by the shifter, (and probably still has the cover on it). In your case I believe the pump is mounted to the upper one with the tang drive (no splines), so all you have to do is unbolt the pump and it stays with the backhoe. No need for disconnects. Your pump also has a speed increaser transmission I believe, so that stays with the pump. A picture would help, but I believe that's the configuration you have.