Backhoe JW-03 Backhoe Problems

[J_J]

RonMar ,

Can you post pictures of the check valve and circuit description/diagram. I have never seen this either. I don't really see the need for an input check valve because the fluid from a cyl will exit to the tank port, unless the valve pools are leaking. Perhaps bad cyl seals.

Just install a hyd gage and trouble shoot the problem.

Are the hoses to the BH connected correctly. Not reversed?

The pump would not care if the valve was leaking. It would just have to work against the back pressure.

 

[J_J]

Just about all loader/BH valves have load checks, to prevent the load from shifting when shifting spools.

 

[wdchyd]

Just the fact it's Chinese it could be any number of things going wrong on this hyd system......

 

[RonMar]

RonMar ,

Can you post pictures of the check valve and circuit description/diagram. I have never seen this either. I don't really see the need for an input check valve because the fluid from a cyl will exit to the tank port, unless the valve pools are leaking.

Here you go. I should have looked at this before I started posting on this problem... I drew this diagram a few years back when I got the BH, to get my brain around how it worked. The diagram in the chinglish manual did not represent it very well. I missplaced the location of the check valve in my head(nothing new there. The check valve is not on the valve input, but on the input to the pressure gallery that feeds the spools. In this position it acts as a single load check... If you use one function at a time, the pump has to provide more pressure than the cylinder currently has on it to move(no uncommanded movement).

Based on this, I believe the OP has a leak in a spool valve, that is allowing pressure to leak past when he activates the boom up command. The fluid takes path of least resistance instead of building enough pressure to lift the boom. This is the same as would happen if you tried to use boom up with another command. This could be a bad seal on a spool, or could be as simple as a spool not centered due to slop in it's linkage to the control handle... Or it could be a leaky relief valve coupled with a leaking check ball... A pressure gauge will tell you more...

 

[cv63usafsfs]

I went ahead and took apart the whole prv and I found a chewed up O ring on one of the pieces. I put a new one on and put it back together and presto, it works. Thanks for all your help guys!

 

[wdchyd]

Good going CV....job well done......and great schem RonMar, You're da man..:thumbsup:

 

[Smalljobs]

I'm glad to see all this help as well as earlier posts on the JW03. I just self imported, factory direct, a frame mounted unit & spare parts, that will arrive end July. All of this will be a great resource for me!

 

[J_J]

Seems like back in post #6, I mentioned checking the pressure on the relief valve, and if you would have done this, you would have found the problem earlier.

 

[cv63usafsfs]

Hey guys,
Another quick question. Where can I find the gaskets that are like rubber coated metal washers that go in between the valve column and the input hoses? I have been everywhere and no one has any idea what they are.
Thanks

 

[wdchyd]

Hyd repair shops use them....