Kubota B21, adjusting hydraulic pressure. Applies to others to I guess.

[joea99]

Posting this is a couple places.

Made up a simple pressure gauge to check relief setting on my B21. A simple T fitting with 5000 psi gauge and a QC coupler on each end.

It does work and show pressure, indicating about 1800 when the relief actuates. About what I expected and will, unless advised otherwise, adjust the relief closer to 2000 as that is the rating. Or maybe it is 2100, I'll look it up.

Couple things.

- Should I adjust the pressure to system rated pressure or leave it as is? I would like a bit more digging and lifting force.

- At first I was confused, only starting my second cup right now, as to why I do not see any pressure at all unless I actuate a valve. Now, having awakened a bit more, it must be because pressure is essentially Zero with the spool in "idle mode" as full flow is going to Tank, thus, no resistance, no pressure. Please help save what is left of my sanity and tell me that is correct.

I guess I need two cups to start the day after all.

 

[joea99]

Posting this is a couple places.

Made up a simple pressure gauge to check relief setting on my B21. A simple T fitting with 5000 psi gauge and a QC coupler on each end.

It does work and show pressure, indicating about 1800 when the relief actuates. About what I expected and will, unless advised otherwise, adjust the relief closer to 2000 as that is the rating. Or maybe it is 2100, I'll look it up.

Couple things.

- Should I adjust the pressure to system rated pressure or leave it as is? I would like a bit more digging and lifting force.

- At first I was confused, only starting my second cup right now, as to why I do not see any pressure at all unless I actuate a valve. Now, having awakened a bit more, it must be because pressure is essentially Zero with the spool in "idle mode" as full flow is going to Tank, thus, no resistance, no pressure. Please help save what is left of my sanity and tell me that is correct.

I guess I need two cups to start the day after all.

Adjusted to relieve at 2000 psi and calling it good.

 

[ning]

Pretty sure max pressure is reached when the circuit is dead-headed. If you measure the pressure ahead of a cylinder, you'll get pressure but probably not relief pressure unless the cylinder is stopped - dead-headed.

 

[joea99]

Pretty sure max pressure is reached when the circuit is dead-headed. If you measure the pressure ahead of a cylinder, you'll get pressure but probably not relief pressure unless the cylinder is stopped - dead-headed.

Yep, that seems to be the case. If spools are all "at rest" the pressure is essentially zero, while moving cylinders there is "some pressure" and when unable to move further, the pressure builds to relief.

That what I did to set the relief pressure higher.

 

[WranglerX]

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[dodge man]

I have a JD 2025r and I can’t remember the spec but I think 1900 to 2100 psi. Mine was on the low side of spec and I bumped it up and it’s about 2450 now. I know on the JD forum people have taken it up to 3000 psi. Of course you are stressing things by doing this, especially if you are maxing it and carrying a heavy load around a lot.

 

[joea99]

I have a JD 2025r and I can’t remember the spec but I think 1900 to 2100 psi. Mine was on the low side of spec and I bumped it up and it’s about 2450 now. I know on the JD forum people have taken it up to 3000 psi. Of course you are stressing things by doing this, especially if you are maxing it and carrying a heavy load around a lot.

I considered boosting it above factory, but, I wimped out. There are two loader cylinders that are weepy as it is.

IF the spanner tool comes in today, I will be resealing them. In a nice cool work area. As it will be near 100 today and tomorrow, seems like a good excuse to spend minimum time outdoors.

 

[Fixastuff]

An old timer I know says most every tractor/excavator/ect should have the pressures re adjusted 6 months or so after purchasing from new. Claimed they set them at the factory but after a little break in they change/lower.

 

[joea99]

An old timer I know says most every tractor/excavator/ect should have the pressures re adjusted 6 months or so after purchasing from new. Claimed they set them at the factory but after a little break in they change/lower.

That's interesting.

I don't recall from the other discussions I read how new or old the machines in question were. Though I think some of them were pretty new.