B21, checking hydraulic pressure. Now I am confused.

[joea]

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, is 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.

 

[whitetiger]

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, is 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.

Yes, the system pressure is near 0 PSI with all spools in neutral.

 

[joea]

Yes, the system pressure is near 0 PSI with all spools in neutral.

Well, that's a relief . . .

 

[TheOldHokie]

Well, that's a relief . . .

Keep in mind that there are probably two reliefs in your test setup. One is the main tractor relief and the other an inlet relief on the control valve. The one thst is set lower wins. Thats why I would test system relief valve pressure by disconnecting the hose on the P port and put the gauge right on the end. That completely eliminates the loader valve.

Dan

 

[joea]

Keep in mind that there are probably two reliefs in your test setup. One is the main tractor relief and the other an inlet relief on the control valve. The one thst is set lower wins. Thats why I would test system relief valve pressure by disconnecting the hose on the P port and put the gauge right on the end. That completely eliminates the loader valve.

Dan

Thanks. Summit states their relief is preset to 2610.

Rather than get too involved, I may try to adjust the main relief, which I have not yet put eyes or hands on and see if it has any effect. If not, I'll have to check the valve itself.

 

[TheOldHokie]

Thanks. Summit states their relief is preset to 2610.

Rather than get too involved, I may try to adjust the main relief, which I have not yet put eyes or hands on and see if it has any effect. If not, I'll have to check the valve itself.

Kubota states theirs is preset to 2000/2100. Why trust one and not the other? If you are checking system pressure eliminate the loader relief. It probably does not matter but its trivial and a lot less work than disassembling relief valves.

Here is the relief on your tractor. You can test it directly without any disassembly by simply connecting your gauge to the loader port on the block and starting tje tractor....

Dan

 

[joea]

Kubota states theirs is preset to 2000/2100. Why trust one and not the other? If you are checking system pressure eliminate the loader relief. It probably does not matter but its trivial and a lot less work than disassembling relief valves.

Here is the relief on your tractor. You can test it directly without any disassembly by simply connecting your gauge to the loader port on the block and starting tje tractor....

Dan

Why trust one and not the other? On this and other forms discussing Kubota hydraulics, most say they find the pressure set 200-300 psi lower than rated. Opinions differed as to who and why, some say set at factory, some say dealer, "for safety". Mine checked out, at the input to the TnT spool valve, to be about 1800 psi.

I just got done adjusting the main relief to show just a hair under 2000 when relieving, to allow a bit for gauge accuracy. Proper pressure according to the FSM is between 1991 and 2062, so, close enough.

The B21 uses a screw/locknut adjust, not shims, so it was pretty much a no brainer for me to try that first.