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?