Backhoe problem

[rScotty]

Sounds like cavitation to me (AIR)

I've always wondered just how much influence that air has in cylinders for FEL and hoes. It seems like cylinders repaired and replaced should put enough air into the system to have some effect - particularly with cylinders where one end is always up....or when replacing a big old BH boom cylinder which weights hundreds of lbs and has gallons of capacity. After a new seal job it has no fluid in it at all. All I can say is I've never been able to tell any difference.

As near as I can tell, the hydraulic fluid purges the air instantly. Just for drill, I do cycle the cylinders after replacing one and am curious enough to lean in to try to spot any difference due to air. But if it happens it is over so quickly I've never noticed anything specific. And I've been doing this a long time.

Just because it hasn't happened to me doesn't mean it can't.

rScotty

 

[Dennis Mohn]

Need advise,
Yesterday my backhoe started acting up.
If i take the boom all the way to one side and then start turning it back, it goes 1/3 of the way, then stops for a second, then keeps going another 1/3, then hesitates again, then goes all the way to the end.
Pretty much same thing with the boom curl, when i extent it all the way out and start the curl, it stops in the middle, then keeps going. Same with the back movement when i try to extend it.

The oil is on MAX, clean as teardrop, so no problem there.

I called the dealer, he said he had never had such an issue. He also called TYM. They also scratch their heads.

The tractor is 2022 Branson 2515R with only 190 Hours.

Any thoughts?

check your feed and return hoses. I have seen where the hose collapses on the inside and shuts off the flow to the equipment. A simple flow test is done into a bucket but the best flow test is done with a flow meter . your dealer may be able to help you with that. I would start with a flow test

 

[Dennis Mohn]

Interesting, meaning there is something wrong with the check valve because it got warmer. In my understanding, if it's función only to prevent backward connection, it should not work at all - get warmer ?

resistance in the relief or cylinder will create heat you would be able to feel.

 

[joea99]

On some tractors (my B21 for example) there is a manual lever/valve that has one position for BH an other for 3pt use.
I experienced some wonky behavior when I forgot or moved with with my knee.

 

[Flogger]

My first assumption by your description would be a restriction or air entering the system. I have never had a relief valve fail that would cause a hesitation like you describe. The swing function is like an amplifier because the boom and stick are moving much farther than the pivot. I can't imagine your machine having more than a central relief on the control valve. It would be a simple task to remove it and look for o-ring damage. Any time you bypass high pressure fluid it creates a heat rise. A $25 infrared thermometer can be a good friend. The combination of low relief and physical tight spots on bushings can cause erratic function.
After all that my first thought was air in the system. Operat it for a few minutes and we if there may be foam in the hydraulic reservoir.

 

[ericm979]

You can get air in the fluid if the suction pipe from the transmission to the pump is allowing air in. A few people have had that happen. But if that was the case then you'd see problems with all the cylinders on the machine once they were operated enough to get the air-laden fluid into them. That'd include the outriggers and the loader. Also the transmission if it was an HST machine.

If you run all the cylinders in and out a bunch and only some have the problem, it's not air from that source. With the rest of the hydraulic system being under pressure I don't think there's a way to get air in except on the suction side.

If it was a restriction in the quick connect on the BH loop, you'd see a problem with the 3pt when the BH is off and the 3pt is lifting something.

 

[2515R Dude]

Update, after removing all internals from the control valve and installing new conectors the problem is still there. It seems to me it changes behavior as time passes. Now if I extend the dipper stick and the boom parallel to the ground and start, let's say all the way from the right, and then start swinging the boom to the left, it immediately starts moving really fast, then at about 1/5 of the way it slowed down almost to the stop, moving really slow with some hesitations on the way almost to the end, and the last 1/8 of the way it moves faster to the end.
My dealer recorded a video and sent it to the brenson/tym. As i expected brenson try to shake of any claims. They say it us supposed to be like that, the distance from the pump to valve and the ramp is too long, the volume of the cylinder becomes larger as the the piston goes out, ad similar nonsense BS.
I told the dealer that I don't get exited when fed b6 BS or any other S for the matter and want to perform a pressure test. He asked for some time off because it is a very busy time for him and we agreed on the week after 4th of July.

 

[K5lwq]

How hard would it be to swap the hoses with the outrigger valves for a test? If the swing and boom work on those valves you can tell your dealer the problem is definitely in the first two valves in the series.

 

[rScotty]

Swapping hoses sounds good. I don't know how many times I've looked at my BH outriggers and thought to myself, "....there sits a rarely-used real dandy of a 2 valve/2 way hydraulic system that only needs a selector valve to be available for all kinds of uses."
Using the outriggers as test beds seems a good place to start.

A pressure tester can be as simple as being just a "tee" fitting with the same threads as the hoses. A suitable gauge is a glycerin-damped 5000 psi stainless type. If the hoses are quick connect it is even easier. It simplifies watching the gauge needle jump if the hose from T to gauge is a standard flixable hose of two or three feet long. Just knowing if the pressure goes up or down when the swing slows would tell you a lot.

If you have the time, do a search here on TBN on the Kubota M59 backhoe swing problem. You will find threads all the way back to about 2008. From day one that model has had occasional problems with the swing. Most commonly problem is that one day it will suddenly swing one way but not the other. In every case it ultimately resolved without anyone ever figuring out why....

How does the Branson BH design their swing geometry? Got a diagram? Some BH use one swing cylinder and some two. Geometries vary. Your dealer sounds great; the tech team sounds a bit lame. That is partly a generational decline in mechanical abilities everywhere ..... but luckily here on TBN we have an advantage over traditional shop mechanics.

rScotty

 

[LD1]

Any way you can get a copy of the video the dealer took and upload it here or post on youtube and give us a link?

 

[piper184]

On my backhoe the swing was wild and chaotic to the point of being nearly uncontrollable. The problem was because of the geometry of the machine the full flow through the valve couldn't be easily feathered by the less than high quality control valve. The solution was to install restrictions in the lines to the cylinders. In my case this was done at the adapter that connects the hose to the valve body. It is internal and no way to see if it is installed unless you take it apart. In my case moving the hoses to another valve without the restriction would cause more issues than it fixes.

The OP's problem certainly sounds like a restriction that is intermittent. If there is a similar restriction device on his BH there may be debris in it that is floating around as the fluid moves back and forth and maybe doesn't completely block the hole in the same manor each time. Otherwise as others have said I would suspect an internal hose failure

It most certainly sounds like a hydraulic problem but as others have said, what if it is a mechanical problem with some of the pivot points. Putting the bucket out as far as it can go and swinging requires the most force from the cylinders and visually exaggerates the image of the problem.

Does the problem occur at the same point in the arc if the bucket is curled all the way back so the hoe is all folded up next to the tractor? An interesting experiment might be to disconnect the cylinders at the pins and get them out of the way. Then with the engine off, try to move the bucket by hand through the entire arc of movement both in the fully retracted and fully extended position. This would separate the mechanical from the hydraulic troubleshooting paths.

 

[2515R Dude]

How hard would it be to swap the hoses with the outrigger valves for a test? If the swing and boom work on those valves you can tell your dealer the problem is definitely in the first two valves in the series.

Great idea, I'll try this.

A pressure tester can be as simple as being just a "tee" fitting with the same threads as the hoses. A suitable gauge is a glycerin-damped 5000 psi stainless type.

It is what he is going to do.

If you have the time, do a search here on TBN on the Kubota M59 backhoe swing problem. You will find threads all the way back to about 2008. From day one that model has had occasional problems with the swing. Most commonly problem is that one day it will suddenly swing one way but not the other. In every case it ultimately resolved without anyone ever figuring out why....

If there no solution it is not going to help

How does the Branson BH design their swing geometry? Got a diagram? Some BH use one swing cylinder and some two. Geometries vary. Your dealer sounds great; the tech team sounds a bit lame. That is partly a generational decline in mechanical abilities everywhere ..... but luckily here on TBN we have an advantage over traditional shop mechanics.

rScotty

I posted the diagram a couple of days ago and will attach it again. Is it what you are looking for?
Yes, it uses two rams. And my dealer is a great guy, however, he is not super knowledgeable in mechanics, it is why he parrots what BS he was feed by Branson geniuses.

The OP's problem certainly sounds like a restriction that is intermittent.

Yes, it is my feeling too, but how to find it

It most certainly sounds like a hydraulic problem but as others have said, what if it is a mechanical problem with some of the pivot points. Putting the bucket out as far as it can go and swinging requires the most force from the cylinders and visually exaggerates the image of the problem.

Does the problem occur at the same point in the arc if the bucket is curled all the way back so the hoe is all folded up next to the tractor?

Yes, at same point, but when the dipper stick and the boom are curled the problem is not so apparent because less force is needed to swing it.

An interesting experiment might be to disconnect the cylinders at the pins and get them out of the way. Then with the engine off, try to move the bucket by hand through the entire arc of movement both in the fully retracted and fully extended position. This would separate the mechanical from the hydraulic troubleshooting paths.

I'll try it for sure, but i suspect it is going to be free because when i manually try to swing the boom, it moves freely as long as the play in joins allows.

 

[piper184]

Interesting that the "hiccup" always occurs at the same point in the arc. That would seem to indicate a mechanical binding not hydraulic.

Here is an idea: Remove both swing hoses from the valve body and put the open ends in a bucket. Then manually move the boom through the entire swing arc. The first couple of times will be purging the oil out of the cylinders and hoses. If there is a restriction you may or may not be able to feel it. I am betting not.

However, once the oil is out if there is any mechanical problem you should be able to feel that. I would curl the bucket up as close to the tractor as possible so that it lowers the mechanical advantage you have. If it moves freely that should eliminate any questions about the hinge pins and possible internal flaw of the cylinders.

If you can feel the hiccup after the oil is out, then you can disconnect one cylinder at the pin and retest. Then the other one and retest.

I don't think you have a mechanical binding problem and if you do it has to be significant to make the hydraulics slow down so you should be able to feel it when swinging through the entire arc by hand.

Other than that all I can think of is back to the hydraulics. As a process of elimination the next idea is a bit of screwing around but with some extra hoses you might be able to plumb the swing cylinders to the FEL valve, say the output lines to the bucket tilt cylinders. That would take the BH valve out of the equation and may give you some clues or confirmations. Flow and pressure tests are probably easier to set up if you have the parts needed.

 

[ning]

Going out on a limb here but
could it be a mechanical binding problem inside a cylinder?

 

[piper184]

Going out on a limb here but
could it be a mechanical binding problem inside a cylinder?

I think a slightly bent rod would cause a cylinder to bind in a certain part of the stroke. Bend it far enough and it just jams and won't go any farther. Other internal damage might be able to cause the same effect.

 

[2515R Dude]

ok, tried some things today:
1. Disconnected the rams from the boom. The BH swings freely by hand. So, no problem here.
2. Ran the rams without connecting them to the boom. Interesting note. The rams are connected between them hydraulically (llok the the diagram on the "Swing Cylinder" part) The oil coming out of one cylinder under the pressure goes to another cylinder to help in the movement, but the movement is not correlated between them as i would expect. They act like there is air inside. When one rod extends, it takes a while for another to start retracting,. I would expect it would to it immediately since all oil coming out of one cylinder immediately goes to another. But they behave with delay like there is a cushion or an absorber.
3. Swapped the hoses with the outrigger valves. no change.

4. I recorded the video, It came out terrible but you can get the idea

 

[oldnslo]

2515
Since the swing cylinders were not mechanically tied together when you did your test the cylinder with least resistance will move first and then 2nd cylinder. One cylinder would have pressure to blind end the other to rod end so blind end would have greater working area and probably extend before other cylinder with pressure in rod end.

Be nice if TYM - Branson had a detailed schematic for the valve stack vs all of us trying to guess what is going on

 

[rScotty]

ok, tried some things today:
1. Disconnected the rams from the boom. The BH swings freely by hand. So, no problem here.
2. Ran the rams without connecting them to the boom. Interesting note. The rams are connected between them hydraulically (llok the the diagram on the "Swing Cylinder" part) The oil coming out of one cylinder under the pressure goes to another cylinder to help in the movement, but the movement is not correlated between them as i would expect. They act like there is air inside. When one rod extends, it takes a while for another to start retracting,. I would expect it would to it immediately since all oil coming out of one cylinder immediately goes to another. But they behave with delay like there is a cushion or an absorber.
3. Swapped the hoses with the outrigger valves. no change.

4. I recorded the video, but YouTube is "checking" it. Dont know how long it will take.

Yes, I did see the original diagram. It's interesting. I've not seen a hydraulic diagram quite like that before. It looks to be set up for ordering parts rather than hydraulic info. What we could use for troubleshooting is a little more detail on how the various valves regulate the flows.

BTW, I believe that the diagram you posted disagrees with the description of how you describe the flow in #2 above. It is hard to be 100% sure without a flow or schematic diagram - and without more details about the T part BY400-8800111.....but if it is a simple T....then the way I see it, that diagram doesn't show that the oil coming out of one cyinder goes to the other cylinder to help in the movement. That's good. It would be odd if it did.

My guess is that in each extension direction the combined expelled flow from the cylinders is returned back through the valve to the sump without any regeneration. Take another look and see what you think.

rScotty

 

[K5lwq]

The fact that it showed no change in behavior when you used the outrigger valve normally would suggest the problem is not the valve but a hose or cylinder. But we have multiple functions involved so that baffles me. I guess it would be possible that the entire valve stack is affected but is only visible on the swing and boom because of its mass?

I really hope the dealer comes up with a solution and we find out what the issue was because this one has me stumped.

 

[2515R Dude]

I really hope the dealer comes up with a solution and we find out what the issue was because this one has me stumped.

The dealer just relays what branson told him, "it is supposed to be like this".

Can you guy look at the video and compare it to your tractor. IS IT SUPOSED TO move like THIS?