BX24 blowing hydraulic filters

[rScotty]

You are picking on the wrong relief valve. I would really like to see a schematic of a BX24. There are changes between my BX22 and the BX23S posted. At any rate, you need to be checking HST charge pressure.

Kubota is an incredibly conservative company. There have been minimal technical changes in the BX hydraulic system from the BX22 (2002) to the BX80 (BX23S type) series of today.
Frankly I'd like to see an extra filter in their system like their larger tractors have, but it is hard to argue with the BX success.

There have been NO changes that would affect Suki's problem. We know what that problem is. There is an obstruction to flow - probably between the filter and the next series of relief valves which are in the HST itself. The charge relief valve is only one of those.
I'm hoping it is a blob of lube/water slime goo, rather than a furball of destroyed parts.

A part of what I hope to do here is try to interest people in hydraulic analysis. It's a wide-open job field throughout industry and throughout the world - at much higher than traditional mechanical wages. The wage makes it difficult to hire a tractor mechanic to work on hydraulics. A one year evening trade school education in hydraulics can sure open a lot of doors.
Yes, I'm biased.
rScotty

 

[ruffdog]

I'm hoping it is a blob of lube/water slime goo, rather than a furball of destroyed parts.

I have been wondering where all the debris from the destroyed filters is going. That can't be good for the pumps and HST.

 

[TMGT]

Scotty, I don't believe the relief in the priority valve is another relief not listed.

Going from memory, the priority valve is made into the back of the hyd pump. The relief shown in that diagram of the priority valve is the same as the main relief shown in the overview of the system (after pump, before everything else).

 

[rScotty]

Scotty, I don't believe the relief in the priority valve is another relief not listed.

Going from memory, the priority valve is made into the back of the hyd pump. The relief shown in that diagram of the priority valve is the same as the main relief shown in the overview of the system (after pump, before everything else).

Could be, that is the problem with schematics - sometimes devices are shown where they are hydraulically correct rather than where physically located. And the BX is an economy model, so it is entirely possible to use one relief valve for two functions. But
regardless of whether there is an additional one in the main system (in fact there are several more), there still has to be one in the priority valve.

One way to check a schematic against reality would be to look at the WSM for the recommended pressure in the priority relief valve and compare that with the setting at the loader control valve input or back on the 3pt.

However, sometimes an obvious relief is simply not shown in overviews. For example on the BX, we know that there are forward and reverse relief valves within the HST itself because a HST requires that they have to be there. But those are not shown until you look at one specific view of details within the internals of the HST. The charge relief serves both, so it is shown in intermediate views.

Good thinking,
rScotty

 

[dougtrr2]

For the OP could you please enlighten me as to exactly what is going on with the filters. You start out saying they are blown and then later talk about them being blown up internally. How do they blow up. Do they start leaking, where? From the gasket, the crimped seam, or a split in the side? How can you tell they are blown up internally? All I can see on a filter are the holes the fluid goes through, are you splitting them open? Some pictures would be nice.

To be clear, I do believe there is something going on, and I am not intending to belittle or troll you. I am just hung up and can't get past the failure mode. I have a BX 24, so I am learning a lot from this thread.

Doug in SW IA

 

[oldnslo]

Could be, that is the problem with schematics - sometimes devices are shown where they are hydraulically correct rather than where physically located. And the BX is an economy model, so it is entirely possible to use one relief valve for two functions. But
regardless of whether there is an additional one in the main system (in fact there are several more), there still has to be one in the priority valve.

Priority valve is a flow control with a totally separate valve for relief function. Priority valve would typically not have any pressure setting. Kubota clearly shows the relief in the schematic and then also as part of the priority valve assembly.
This relief protects the pump in this system.

One way to check a schematic against reality would be to look at the WSM for the recommended pressure in the priority relief valve and compare that with the setting at the loader control valve input or back on the 3pt.

However, sometimes an obvious relief is simply not shown in overviews. For example on the BX, we know that there are forward and reverse priority valves within the HST itself because a HST requires that they have to be there.

HST does not have forward and reverse priority valves. They do have forward and reverse relief valves for limiting the closed loop or drive pressure.

But those are not shown until you look at one specific view of details within the internals of the HST. The charge relief serves both, so it is shown in intermediate views.

Good thinking,
rScotty

 

[rScotty]

Priority valve is a flow control with a totally separate valve for relief function. Priority valve would typically not have any pressure setting. Kubota clearly shows the relief in the schematic and then also as part of the priority valve assembly.
This relief protects the pump in this system.

Look at the expanded view of the steering priority valve. There it is. Yes, it could serve several functions.

HST does not have forward and reverse priority valves. They do have forward and reverse relief valves for limiting the closed loop or drive pressure.

Good catch, my fault to use the wrong word. Priority valving there makes no sense, and it would be redundant since we are changing direction...even if it were there. I changed the original to read "forward and reverse relief valves" which makes sense with the rest of the text, even if you have to look deeply into the HST disassembly in the WSM to access them. .
rScotty

 

[Redlined0002]

Problem is in you loader valve

 

[oldnslo]

Problem is in you loader valve

Would you care to explain how the problem is the loader valve?

 

[dicktill]

Yes, important that there are relief valves everywhere. Each hydraulic circuit has at least one. On schematic diagrams, relief valves are the little box with a squiggly tail and a dotted line connecting one side with another. Their main function is to open up and return any overpressure back to the tank. That tank return path is sometimes shown and sometimes just assumed.

Relief valves are not always shown unless the view is expanded. For example, look below. We know that the steering priority valve must have its own relief valve, because every circuit does. But although we see the steering priority valve, its relief valve s not shown in the overall diagram. To find it we must dig deeper into the WSM. The same goes for the relief valves in every circuit. There are many. In fact, the HST has several internal ones. All are in the WSM if you look deep enough.

<snip>

rScotty

@rScotty: Sorry for the slight thread hijack, but can the steering relief valve be in the steering valve? I have looked at the hydraulic schematics and the workshop manual for my 2022 Massey Ferguson GC1723EB and cannot find a separate relief valve for the priority (dividing) valve within the housing that MF refers to as "the control valve", which also contains the valve for the 3-point. There is only one relief valve within it and that is set for 1920psi.

Thanks, Dick