FEL slowly goes down.

[TheOldHokie]

I think the real reason is that they saved about $.04 by using a cheaper seal.

They could save the entire cost of the loader seal by eliminating it entirely and the cylinder would still not leak down. The cylinder piston seal has nothing to do with the loader arms dropping.

Dan

 

[William1]

Drop is normal. Next time, put jack stands underneath for safety, just as you would when jacking up and working under a car.
Always park the tractor with the FEL on the ground. If you have a BH, put the locking pins in to keep the boom from sagging.
Stay safe, my friend.

 

[William1]

Hey all, ive got a 2019 BX23s with hydraulic leakdown issues. The stablizer arms slowly lower over time. I have to park in a tight space, but every time i operate this machine, i must remember to raise the stabilizers, otherwise ill clip the wall beside it. It has been this way since purchased new, but the responses i had found in the blogosphere led me to believe it was normal. HOWEVER, i have since purchase a neglected and abused 40+ year old JD that i can raise the 3 pt with bush hog attached. Walk away for days at a time and absolutely no visible setting. What is the difference? A lot of weight on an old beat up machine at an awkward cantilevered angle vs very little weight on a new and pampered machine with the minimal load going almost straight down onto the pins, thus not really stressing the cylinder hydraulics. Can someone give a reasonable explanation as to why this would be an acceptable design if it is correct? Thanks.

If... stabilizer sag is a issue, use a ratchet strap between the two. Not a lot of force is generated by them wanting to fall, so a small one will be fine. Being the strap will be in the way when trying to mount the BH, you do not have to worry about forgetting it is on. I do the strap on my BH when the BH is off the tractor.

 

[lynnmor]

They could save the entire cost of the loader seal by eliminating it entirely and the cylinder would still not leak down. The cylinder piston seal has nothing to do with the loader arms dropping.

Dan

I understand that idea, but a "perfect" seal will slow the drop caused by a leaking valve.

 

[TheOldHokie]

I understand that idea, but a "perfect" seal will slow the drop caused by a leaking valve.

How?

Dan

 

[lynnmor]

How?

Dan

Oil needs to go in or out of that cylinder in order for it to go down. That oil needs to get to a leaking valve, it can get there by way of bypassing the piston.

 

[TheOldHokie]

T

Oil needs to go in or out of that cylinder in order for it to go down. That oil needs to get to a leaking valve, it can get there by way of bypassing the piston.

DCV leakage oil exits the cylinder via the ports at either end of the cylinder. The piston seal, which is in the middle of the cylinder, can do nothing to prevent or even slow down the reverse flow of oil out those ports. And BTW - o-ring seals are damn near perfect. That's why POCVs work so well at eliminating cylinder drift due to spool leakage.

Dan

 

[The Plunk]

If... stabilizer sag is a issue, use a ratchet strap between the two. Not a lot of force is generated by them wanting to fall, so a small one will be fine. Being the strap will be in the way when trying to mount the BH, you do not have to worry about forgetting it is on. I do the strap on my BH when the BH is off the tractor.

This guy makes nice product. Kind of expensive but nice.

BX / BH70 Outrigger Locks

BX / BH70 Outrigger Locks

specialtyrepairscustommods.com

 

[frydaddy96]

An older post but I'll ad my .02. My BX2350 that is 18 years old with 1700 hrs has always held the boom where it was stopped with extremely minimal down drift. It might have dropped a few inches over several days. Even when the bucket was full of wet dirt it did not drop while moving the dirt around the yard. Just yesterday though I noticed that it was lower than where I had set it when loading some logs onto the forks. After I dumped them I noticed when I raised the boom, it would immediately drop 4-5 inches, then stop. When I put down pressure on the boom with the bucket against the ground, it would immediately drop the front tires back to the ground. So I'm currently troubleshooting to check if it is the boom cylinders or the control valve or something else. No leaks visible and when it drops it is even, not like one cylinder went bad. Seems odd if both cylinders went bad at the exact same time.

 

[lynnmor]

An older post but I'll ad my .02. My BX2350 that is 18 years old with 1700 hrs has always held the boom where it was stopped with extremely minimal down drift. It might have dropped a few inches over several days. Even when the bucket was full of wet dirt it did not drop while moving the dirt around the yard. Just yesterday though I noticed that it was lower than where I had set it when loading some logs onto the forks. After I dumped them I noticed when I raised the boom, it would immediately drop 4-5 inches, then stop. When I put down pressure on the boom with the bucket against the ground, it would immediately drop the front tires back to the ground. So I'm currently troubleshooting to check if it is the boom cylinders or the control valve or something else. No leaks visible and when it drops it is even, not like one cylinder went bad. Seems odd if both cylinders went bad at the exact same time.

Is the fluid level the same as before? Did you exercise all cylinders several times to the full extent of their travel?

 

[frydaddy96]

Is the fluid level the same as before? Did you exercise all cylinders several times to the full extent of their travel?

Yes, fluid level is good, checked again today. Cycled the boom to its full extents several times no change. Went to my wet dirt pile and got a full bucket with no problem, lifted it without issue. I did notice that the higher the boom, the less drift down there is. With the bucket full and sitting mid way (after it does the 4 inch drop) there may be a slight drift down but it is very very slow.

 

[TheOldHokie]

Yes, fluid level is good, checked again today. Cycled the boom to its full extents several times no change. Went to my wet dirt pile and got a full bucket with no n, lifted it without issue. I did notice that the higher the boom, the less drift down there is. With the bucket full and sitting mid way (after it does the 4 inch drop) there may be a slight drift down but it is very very slow.

My guess is bad/dirty load check valve.

Dan

 

[Henro]

My guess is bad/dirty load check valve.

Dan

First time I head of a load check valve in a loader control valve for a BX Kubota...Or any small Kubota tractor really.

Tell us more Dan...

Edit: I meant anywhere in the hydraulic circuit, not just the control valve. Seems like that would eliminate the float function for the loader.

 

[TheOldHokie]

First time I head of a load check valve in a loader control valve for a BX Kubota...Or any small Kubota tractor really.

Tell us more Dan...

Large or small, load check valves are standard in almost every loader valve made in the last 50 years.

They dont prevent cylinder drift. They prevent a held load from dropping during a spool trandsition into/out of neutral. Diagram below was chosen at random. The load check is item #40 - one for each spool in the valve.

Dan

 

[Henro]

Thanks Dan, One more thing to read up on now.

 

[TheOldHokie]

Thanks Dan, One more thing to read up on now.

By all means readf all you want but most descriptions are pretty technical and about as clear as mud. Here it is in a nutshell

This is a crude cutaway view of a two spool parallel circuit loader valve.

The top view shows oil flow when both spools are in neutral. Low pressure oil enters the neutral core on the left, then passes through both spools, and out the right side. Another core is teed off the inlet section and runs parallel to the neutral core. The parallel core deadends at the outlet section. When the pump is running and the spools are in neutral the parallel core is filled with standby oil at the same pressure as the neutral core.

The bottom view shows what happens when the left spool is shifted. The neutral core is closed off causing pressure to rise in the upstream portion of the neutral core and the full length of the parallel core. Pressurized oil from the parallel core is what actually feeds the work ports.

Now to the load check valves. When a spool is shifted the neutral port is blocked and the associated work port is uncovered allowing pressurized oil from the parallel core to flow out the work port. Depending n the design of the glands on the spool there is a small overlap between complete closure of the neutral core and initial opening of the work port. At that point in the shift there is a potential for pressure already on a loaded the work port (e,g, raised loader) to flow backwards into the valve causing the load to drop until pressure reaches equilibrium. To prevent that a simple one way check valve is placed between the parallel core and the work ports. it is closed preventing backflow until pressure in the parallel core rises to exceed work port pressure. As you can see the pressurized oil in the parallel core is available to all spools when any combination of spools is shifted.

Hopefully that's a little clearer than mud.

Dan

 

[Henro]

By all means readf all you want but most descriptions are pretty technical and about as clear as mud. Here it is in a nutshell…

Dan

Nice explanation. Thank you

So is there one load check valve for each direction of movement?

Frydaddy96’s experience is that his issue occurs whether force felt by the bucket is pushing down or up.

After I dumped them I noticed when I raised the boom, it would immediately drop 4-5 inches, then stop. When I put down pressure on the boom with the bucket against the ground, it would immediately drop the front tires back to the ground…

 

[TheOldHokie]

Nice explanation. Thank you

So is there one load check valve for each direction of movement?

Frydaddy96’s experience is that his issue occurs whether force felt by the bucket is pushing down or up.

One load check per spool. It is n the feeder passageway common to both work ports. Only one can be connected to pressure at any given time.

As I read it Frydaddys experience is both ways. The rapid 4" drop is a classic symptom of a load check failure. The subsequent drift is spool leakage.

Dan

 

[Henro]

Thanks Dan,

I now understand the load check valve is in the pressure circuit within the valve, after the P port and before the spool. And that there is one load check valve for each spool. If the load check doesn’t function properly, the loader will drop until it does function. If it were missing or failed totally and stayed open all the time, the loader would never hold a load and would drop back to the ground. Is this a true statement?

And naturally, if it was misfunctioning, and taking a few seconds to close, then the loader would move some amount during that time. And if the bucket was pushing down on the ground enough to lift the wheels off the ground, then the wheels would drop back towards the ground when the spool was centered in the valve, until the load check valve closed fully, or until the wheels were back on the ground.

If the above is correct, I have a follow up question: Where does the fluid go that leaks back through the load check valve and out the P port? I can imagine the answer but I’d rather hear it from somebody that knows!

 

[TheOldHokie]

Not exactly.

When a spool is transitioned out of neutral there is a brief moment in time when the pressure at the work port thats being uncovered may be higher than the pressure being built on the pump side port thats being closed. The load check prevents reverse flow from work port to pump side during that very brief moment in time.

Without the load check the load can drop slightly before the pressures equalize (almost instantly) and everything works as expected. In the good old days valves did not have load checks and loaders were jerky. Load checks were added to prevent that.

If I were the OP I would remove, nspect, and clean the load check valve on the boom spool. Its just a poppet valve with a few little Jesus!! parts.

Dsn