BX24 Increased pressure with shims

[310-510]

I finally managed to test the pressure and found my BX24 had 1740 PSI at WOT and warm fluid. I added 4mm shim and the pressure went to 1900 PSI at WOT. WOW, what a difference. I have a tractor that can lift a full bucket, a backhoe that can really scratch the dirt, and I can get by running at 2500 - 2600 RPM for most work. The most noticeable lift is with the front bucket forks. The BX will now lift a 440 pound 5' flail mower on a pallet when before the modification, it would not even curl the weight. Just to be clear, it won't lift the flail mower very high and it won't lift the flail mower very fast, but all I needed to do was be able to lift the flail mower to move it in and out of my trailer.

OK, now that I think adding pressure is the holy grail of making my BX great, what component will I be breaking or shortening the life of?

 

[radman1]

I wouldn't be too concerned. The increase in pressure was only about 10%. Just be careful about lifting too much and making the back end too light. At 10%, bending or breaking something is not likely. Increased pump wear is not a real factor.

 

[Matt_Jr]

That's awesome. I've never had problems lifting with mine though. It's lifted anything that would fit in the bucket. However forks do lesson lifting capacity. My guess on what could end up having problems in the future is nothing with that small of an increase. These lil' 'botas are tough. Keep an eye where the arms attach and frequently check for metal for fatigue/cracks on the loader arms and don't let any thing down fast and stop the lowering of the bucket too suddenly. My guess is you'll be alright.

 

[GreenWannabe]

Does the BX24 manual give maximum operating pressure? The specs on the website don't.

 

[310-510]

Does the BX24 manual give maximum operating pressure? The specs on the website don't.

The Kubota dealer here in Omaha indicated that everything in the hydraulic system was rated at 2000 psi or greater. How true that statement is, I don't know.

 

[AndyinIowa]

I wouldn't be so quick to dismiss a pressure increase as harmless to the system. Some of our tractors use gear pumps for aux. hydraulics.


Aluminum gear pumps undergo a 'cut-in' at the factory. They are run at a pressure close to the shipping pressure (depends on manufacturer). During this process, the gearset literally cuts into the pressure plate. This ultimately increases efficiency, but also creates a LOT of contamination. The contamination isn't a problem because the test stands are designed to handle it.

Now, imagine the pump in the field. If you increase relief pressures, you take the pump above the factory cut-in conditions, and the pump will cut in FURTHER. This literally means the gear set cuts away more material as the pressure seats the gear set further in the pressure plate.

The results are that shavings are produced and dumped into the hydraulic system. I have a LOT of experience with customers in the field damaging their systems this way. Typically the shavings end up in the valves or chew up seals. If the dealer checks the relief pressures and determines that the system is above spec, warranty is void!

Bottom line -don't think you get a pressure bump for free. You are introducing large particle contamination right in the heart of your system. You are risking waranty (if tractor is still under warranty).

FYI piston pumps are not subject to this situation.

IowaAndy

 

[3RRL]

I did a search and the only thing I found was a thread on an Exploding Hydro Filter
In the first post near the bottom, the poster says the factory spec is 1840psi for the BX24.

 

[Skyco]

Workshop manual says 1778 to 1849 at maximum engine speed, oil temp from 104 to 122degF on one page but then oil temp is shown as 113 to 131degf on another page.....so I'd say around 120degF is good

 

[Zick]

Do you have any pictures of your test setup and where you shimmed exactly?

 

[dfkrug]

Some of our tractors use gear pumps for aux. hydraulics.

Aluminum gear pumps undergo a 'cut-in' at the factory.....

All CUTs I have had use gear pumps.....I assume steel gears inside aluminum
housings. The ones I have dissassembled are built that way, like engine
oil pumps and HST charge pumps. What tractors use piston pumps for AUX
hydraulics? I know piston pumps are used in HSTs......

It is interesting to note what the hydraulic system pressures designed into
the various CUTs are. It says something about how robust the machine is
and/or how good the hyd pump is. It seems many tractors in the 30hp/3000#
range have 2000psi hyd systems and many of the same size have 2500psi
systems, from brand to brand. Sub CUTs seem to be mostly under 2000psi.