Backhoe swings right, but not left

[rScotty]

This problem just happened on our 2008 M59 with 340 easy hours. Most of it's use is to lend a hand moving dirt and rocks here on our mountain land.....along with plowing snow with the bucket in the winter. One operator, regular maintenance, and although it lives outside, it does get an old tarp draped over the operator's compartment when parked. All in all, I'd have to say it leads a pretty soft life for a construction type machine.

So far that's worked out well for both of us. But yesterday an odd thing happened with the backhoe swing. I was moving small rocks off the road with the bucket and thumb - light, easy work - and all of a sudden the boom just stopped swinging to the left. No noise, no warning and no load at the time. The swing just stopped working. It had just swung about half way to the right and then wouldn't come back left for nothing. With a little experimentation is turns out that it will swing to the right as nicely as always, but push the LH backhoe control lever control to the left to make the boom swing left and nothing happens at all. No change in engine RPM or anything. My first thought was that it had to be something simple. Probably just one of the connections between the hand lever and the BH valve rack had come loose. But the lever fells correct, and a quick look at the valve rack under that plastic cover shows nothing amiss there. Crawling underneath shows no leaks or damaged hoses. The hydraulic fluid is properly full.

After a little more experimentation it turns out that if the control lever is put in the left swing position a person on the ground can push the boom to the left fairly easily. So nothing is binding in the pivot or cylinder. All other backhoe movements - including the swing to the right - seem to work normally and with full power.

So does this mean the problem is in the valve? Somehow that just doesn't seem right when I can see that the control is working the valve slider normally and with what looks to be full motion....or at least I'm supposing it's moving full motion. Is there some sort of control or swing lever override that I'm overlooking? Has anyone else had this happen on a backhoe? What could it be?
Thanks, rScotty

 

[Dozernut]

Sounds like a bad seal in the swing cylinder. Remove the cylinder and rebuild or take it to a hydraulic repair shop.

 

[rScotty]

Sounds like a bad seal in the swing cylinder. Remove the cylinder and rebuild or take it to a hydraulic repair shop.

That might be it. But maybe not. I was thinking it would move just a little bit at full RPM and no load even with a bad seal? Still, worth a check.

OOps...as I look at the BH and the shop manual this morning it turns out that there are two swing cylinders mounted as a handed pair and they are both powered in both directions. So as one is extending under power the other one is retracting under power. One cylinder ought to be more than enough to swing it.

It seems unlikely to me that both of those cylinders would go out at the same moment...and blow their internal seals in exactly opposite ways.

That sounded good until I see there are two powered cylinders. This M59 has a pretty sophisticated backhoe.
thanks, rScotty

 

[boggen]

it is either one of the cylinders or the valve. is what i would assume.

if you have the shop manual for the backhoe. see if there any sort of "check valves" or mechnizism in the valve body itself. maybe one is messed up. or perhaps something caught up in the valve body keeping a check valve open. check valve could be simply a spring and a little ball, to small flat plates, to actual flapping check valve.

the 2 cylinders for swing. see if they are plumbed in series or parallel. maybe being able to disconnect one cylinder. and use a hose to by pass it. might give detail of which cylinder might have went bad.

any chance did hyd oil get to low, and allowed air into the system. and you just have not ran things long enough to work the air out of the hoses and cylinders?

if you have shop manual see if you can find a plumbing schematic/diagram that shows direction fluid is suppose to flow in. perhaps you might be able to narrow something down.

 

[EE_Bota]

Unless this is an election year thing, my assumption (based on both powered both ways) is that they are piped in parallel on the same spool.

Lets use RE for Rod end and PE for piston end. L is left and R is right.

Suppose swinging right takes pressure to L-PE and R-RE. So long as the piston cups are good there, it goes right (and the other ports are just going to tank.)

Now suppose on swinging left we send pressure to L-RE and R-PE. If we are in parallel like my guess, if either one of those piston cups can pass the fluid easily, the unit may not move, but instead the fluid goes to the path of least resistance.

If I am right, and I probably am not...what with no diagram and all, one could remove the hose from L-PE and check for massive flow or from R-RE and check for massive flow, and none should exist since there is no movement. But if it is leaking through the cups directionally, fluid will be flowing, and that will tell you which cylinder is bad, and which cup is bad.

Hope this helps...it is an assumption based on what you said...powered both ways, both cylinders.

I can't see them being piped in series really...possible, but it seems unlikely.

I have seen cups that are highly directional, and the pressure reinforces them. I have also seen a piston ring deal that is not directional at all as best I can tell. I don't know which you have, and this was all a shot in the dark telling you what I would look at were I you.

Edit: My junk has two cylinders, and each is powered one way, so a regular valve can control mine, and let oil out of one sides piston, and put oil in the other cylinders piston. So, both cylinders have one hose each, and the rod end is ported to air, so each is single acting. I assume by what you said, you have four total hoses for those cylinders. I assumed further that only one spool controls them both, and one piston is paralleled with one rod side, and other piston paired with the opposite rod side.

 

[murphy1244]

right cylinder not working. find a way to bypass control to cylinder to see if it works. if it does,its the valve , if not ,cylinder.

 

[TBarD]

I haven't checked the shop manual, but if both swing cylinders are powered during a swing - they must be otherwise the unpowered one would work against the swing - then the valve is more likely the problem since the problem is directional. In any case this one probably requires return to a dealer to fix the problem. This is unfortunate, but you may only need to return the backhoe if it can be removed.

I haven't yet removed the backhoe on my M59, but I did succeed in removing the pins yesterday. They were surprisingly easy to remove, once I lifted the back end enough. More on that later. I am just getting back to work on the tractor in preparation for heading up to work on my place in Colorado this weekend.

Please followup, as any M59 issues are of great interest for those of us who have one.

 

[Martian]

I haven't checked the shop manual, but if both swing cylinders are powered during a swing - they must be otherwise the unpowered one would work against the swing - then the valve is more likely the problem since the problem is directional. In any case this one probably requires return to a dealer to fix the problem. This is unfortunate, but you may only need to return the backhoe if it can be removed.

I haven't yet removed the backhoe on my M59, but I did succeed in removing the pins yesterday. They were surprisingly easy to remove, once I lifted the back end enough. More on that later. I am just getting back to work on the tractor in preparation for heading up to work on my place in Colorado this weekend.

Please followup, as any M59 issues are of great interest for those of us who have one.

I think this is on the money. My guess would be the valve as you would be able to find some movement or at least hear something trying to work with the valve working. A simple look at the valves may reveal that something as simple as a sheared pin is there in the linkage that doesn't allow the valve to open/close. If this is the case it would be a very simple repair. Otherwise, I'd take it into the shop. Hopefully your still under warrantee.

And yes - I would imagine all you'd need to drop off is the backhoe. Assuming you can get it on a trailer and they can get it off!

 

[rScotty]

the valve is more likely the problem since the problem is directional.

In any case this one probably requires return to a dealer to fix the problem. This is unfortunate, but you may only need to return the backhoe if it can be removed.

Please followup,

PROBLEM FIXED!!

Well, I guess we'll never know exactly what the problem was, but with a little bit of help the problem appears to have fixed itself.
Maybe this self-healing is a Kubota feature?

Here's how it went.....
Yesterday morning I read up in the shop manual and then took my coffee to the barn to visually go over as much of the M59 hydraulic system as I could find....and found nothing to change. Even the oil still looked good.

I was kinda hoping for an overnight miracle, but just like yesterday the BH boom still wouldn't power-swing in one direction. But also just like yesterday, it could still be swung back the other way by hand if the control valve was held open. All other systems and controls still worked normally.

I'd rather do my own work than involve the dealer. Even though it would be an nice drive over there and he does have one very good...maybe even excellent mechanic. But I've always believed that the best work is always done by a concerned owner....and like it or not; that's me.

So...what I did was decide to get some more information. It occurred to me that I could tilt the tractor by putting down just one of the backhoe support legs. And with the tractor tilted, I could swing the boom one way under power and let gravity swing it back the other way. I don't know what I thought I was doing, but it seemed like a good way to get some more information. Surely better than doing nothing at all. And a whole lot better than disconnecting random hydraulic hoses, parts, and pieces...

It turns out there wasn't quite enough tilt for gravity to swing the boom by itself so I had to lightly bounce the boom with the boom cylinders to get the gravity swing to happen.

And I swung it that way three of four times just sort of sipping coffee and thinking what to do now? When ALL OF SUDDEN THE POWER SWING started working again in BOTH DIRECTIONS. With no noise, no warning,....not even a hiccup or apology. Just as smoothly and controllable as it's always been.
I used it the rest of the day and it was perfect; nice weather, nice tractor....
So what happened??
rScotty

 

[EE_Bota]

PROBLEM FIXED!!

Well, I guess we'll never know exactly what the problem was, but with a little bit of help the problem appears to have fixed itself.
Maybe this self-healing is a Kubota feature?

Here's how it went.....
Yesterday morning I read up in the shop manual and then took my coffee to the barn to visually go over as much of the M59 hydraulic system as I could find....and found nothing to change. Even the oil still looked good.

I was kinda hoping for an overnight miracle, but just like yesterday the BH boom still wouldn't power-swing in one direction. But also just like yesterday, it could still be swung back the other way by hand if the control valve was held open. All other systems and controls still worked normally.

I'd rather do my own work than involve the dealer. Even though it would be an nice drive over there and he does have one very good...maybe even excellent mechanic. But I've always believed that the best work is always done by a concerned owner....and like it or not; that's me.

So...what I did was decide to get some more information. It occurred to me that I could tilt the tractor by putting down just one of the backhoe support legs. And with the tractor tilted, I could swing the boom one way under power and let gravity swing it back the other way. I don't know what I thought I was doing, but it seemed like a good way to get some more information. Surely better than doing nothing at all. And a whole lot better than disconnecting random hydraulic hoses, parts, and pieces...

It turns out there wasn't quite enough tilt for gravity to swing the boom by itself so I had to lightly bounce the boom with the boom cylinders to get the gravity swing to happen.

And I swung it that way three of four times just sort of sipping coffee and thinking what to do now? When ALL OF SUDDEN THE POWER SWING started working again in BOTH DIRECTIONS. With no noise, no warning,....not even a hiccup or apology. Just as smoothly and controllable as it's always been.
I used it the rest of the day and it was perfect; nice weather, nice tractor....
So what happened??
rScotty

I really don't know what happened, but I am guessing a cup seal caught the flow and thereby got reinforced.

But I really don't even know if it has cup seals in the cylinders. I don't know how it is piped. I don't know if it is in parallel (one piston side in parallel with the rod of the other cylinder, etc.) I used to tell folks that telling me what they don't know is not helping...so I will heed my own advice and stop right there.

I was wondering if I was talking out of my hat with my analysis, but I have found a hydraulic diagram that supports my theory buy searching "backhoe hydraulic diagram" on Google.

HYDRAULIC SYSTEM DIAGRAM (SERIAL NUMBERS 319995 THRU 342573 ONLY)

Compare that diagram to my comments earlier, and do tell us if it matches yours (vis a vis the swing cylinders only), if you don't mind.