Kubota backhoe hydraulic problem

teachingscience · Mar 10, 2012

Recently bought a L4310 kubota with backhoe. At first there was no power on the hoe at all, finally found a collapsed intake hose to pump. Now it has good power except on the cylinder that extends the boom out. It sounds like the pressure relief is releasing anytime I pull very hard but the rest have more power than it. One standard also seems to have less power than the other side. The valve couldn't have a separate pressure relief on only one circuit could it? ONE more problem, If I try to slowly raise the weight of the tractor it will drop a couple of inches before it starts to lift. I have no idea what can cause that. Hope some of you wise men can help me. I'm lost on this one. Its too new for me LOL

Charlie

mhb@ufe · Mar 10, 2012

Backhoes do have circuit relief valves which are set higher than the main felief valve pressure. The dropping before lifting could be that the piston is loose on the end of the rod inside the cylinder. That allows oil to leak by until the oil pressure seats the piston on the rod. When you say one standard has more power than the other side are you talking about the stabilizers?

Mark

teachingscience · Mar 10, 2012

Yes, sorry I'm new to backhoes and don't know all the right terms yet

The dropping happens on the stabilizers and the boom if i just ease the levers to move slowly. Can air cause it to do that?? Also, when we replaced the collapsed hose, it had been put on with teflon tape. Could some it have gotten in the valve and caused these syptoms??
Thanks for the advice
Charlie

samn40 · Mar 10, 2012

I had big problems like yours after replacing a burst hose on a massey digger. sometimes the rams would extend but not retract plus the dropping before lifting etc. Turned out my brand new hose was breaking up inside and had filled the spool valve chest with small pieces of rubber. Check valves were sticking as were the relief valves and non return valves. Ended up having to clean the whole thing out including checking every little valve and spring.
Good Luck....Sam

jm. · Mar 10, 2012

Yes each curcit on your hoe (BH (90) has a relief. Now on to the stablizers what is hapening there is not only does the stabliser valve have relief it also has a antidrop valve or popett. Takes a little preasure to break it off center before the cylinder will extend. You are probably going to have to take a look at each seperate valve or have a book to guide you .No adjustment on the antidrop popet just have to replace the parts.

Roy Ward · Mar 10, 2012

Sounds like you have trash in the relief valves.
Could have gone all over the system.

Kubota backhoe hydraulic problem

teachingscience

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mhb@ufe

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teachingscience

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samn40

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jm.

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Roy Ward

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