HELP! My Backhoe won't swing left!

[avc8130]

Hello ac. I was just about to send you the link when I saw that you had found it.
http://www.tractorbynet.com/forums/k...t-but-not.html

I'm glad it worked for you and hear the same trick has now worked for several other owners of M59s and L48s.
And yeah....I'm still marveling at the pure dumb luck that caused me to try doing that in the first place!
Nobody has figured out for sure what causes it. Your idea of something stuck in the relief valve seems as good as any. Maybe letting the boom move under gravity back-flushes the relief valve..... Sounds logical.

Mine was like yours, the control felt perfectly normal but moving it didn't do anything. Not even the slightest vibration, feel, or sound. And when it started working again it just started like nothing ever happened. Nor has it happened since.
Better to be lucky than smart,
rScotty

rScotty,

Have you put some hours on your hoe since it happened? I generally don't use my hoe often. My machine gets used more for the FEL and brush hogging, so I won't know if this is a "permanent" fix for quite a while.

ac

 

[rScotty]

rScotty,

Have you put some hours on your hoe since it happened? I generally don't use my hoe often. My machine gets used more for the FEL and brush hogging, so I won't know if this is a "permanent" fix for quite a while.
ac

It happened almost a year ago now. No, whatever the cause, it hasn't repeated. I haven't used the tractor much this past year, only about 35 hours by the gauge clock. About half of that time was recently doing what I'd call pretty hard backhoe use (lots of rocks) in a narrow place down by the creek so it required a lot of swinging all the way to the stops to dump the bucket.
BTW, I don't know if it is pertinent but it might be....I tend to use my hoe at a fast idle instead of at full RPM. That's a personal choice. I've found it has about the same power regardless of RPM and in addition to not liking the racket of full RPM I also don't like the way working at full chat throws the hoe around. So I run mine slower.

The more I think about what happened, the more I lean towards the "piece of crud caught in one of the relief valves" theory. These Kubota backhoes are a sophisticated system with many relief valves, and that theory makes sense from a single-sided hydraulic flow point of view and also from the the way the boom suddenly stopped swinging and then started working again without any warning, no change in the sound, and no shuttering or vibration.....and no lasting effect I have seen.

So what I did was to buy a couple of new relief valves - BTW, expensive little suckers - which are sitting in their factory packaging on a shelf in the barn "just in case". If it happens again I think I'll carefully replace the most likely suspect relief valve and take a careful look inside that valve.

Until then I'm not going to worry. In fact, until you and several others mentioned that the same thing happened I'd forgotten about it.
Regardless of why, the same thing has now happened to enough of these similar models that it would be nice to hear from Kubota.
And three cheers for TractorByNet!
rScotty

 

[avc8130]

Mine is doing it again. I don't know what happened, but I went to move the machine and needed to swing the hoe to reduce my overall length. The hoe swings fine to the right, but doesn't swing left again.

I tried picking the right side up and letting it return with gravity 12+ times. It still doesn't swing left under power.

PLEASE HELP!

ac

 

[sandyc]

check the connection of the lever to the valve. sounds like a bolt loosened.

 

[Stonehaller]

There are port relief valves on the swing valve. The left could be stuck open so it just exhaust pressure. If that is the case, then you should be able to push it by hand like you said when the valve is held to the left. You could try tapping on them to see if that frees it or you could take the port relief off the valve and disassemble and clean it. The port relief for the left is on the top (linkage side) of the valve. Make sure the jam nut did not come loose allowing the relief adjusting screw to back out. I would check the other items below before disassembling the valve.

Check the linkage to the valve spool to make sure it is giving full travel of the valve spool. The spool is pushed in for left swing. There also could be dirt in the cap over the spring end of the valve not allowing full travel. You could take the cap off to check.

Make sure the dump valve for the swing pump is fully in the backhoe position.

Make sure your quick disconnects are fully seated.

 

[avc8130]

I don't know what it is...

I tried the "gravity return" method again, this time at 2500rpm and guess what? IT WORKS.

I'm going to check everything external out just to make sure it is ok.

ac

 

[hummin24]

Kubota B21 backhoe 751 won't swing -

Thanks! This method just worked great for me. 2k RPM. Right stabilizer down and hold left swing open then right and so forth a few times. Operational now.

 

[johnk]

At least the 4 year old thread helped you out!!

 

[avc8130]

At least the 4 year old thread helped you out!!

I just wish we knew WHY.

ac

 

[hummin24]

Uhh, what?