Backhoe B26 hydralics bypassing

[J_J]

If you have several reliefs in a circuit, you can set them all the same if the components will take the pressure. The reliefs in the valves are there to protect anything using fluid from that valve.

If there are weaker components down stream, the relief is set for that valve/circuit to protect against higher pressure produced by the tractor hyd pump.

If you are going to talk to someone at the dealership about the hydraulics, it should be the service tech/mechanic. A lot of supervisory people are not qualified to answer tech questions, and will try and BS.

 

[MarkV]

Woody this may help you some. Go to TractorSmart.com is your online source for Kubota online parts. and follow the directions for down loading the B26 parts manual. You don't actually down load it, they send you a PFD file by e-mail so it may take a day. It has pretty good graphics and the part numbers. A handy thing to have around.

MarkV

 

[woody]

great info and thanks alot, I have been out in the shop fixing me up a gauge. I check the pressures myself and came up with 2200psi for the fel and the same on the BH. the next time I talk to the service rep I'll know more about what I am talking about.

 

[mrennie]

The shims to adjust the PRV are under a cap on the bottom of the FEL valve assembly. Even though it is on the FEL valve my understanding is that it controls the max pressure for the FEL, BH, and 3PH. The factory manual procedure for checking it says to remove one of the lines at one of the FEL cylinders and attach your gauge there, then to try curling the loader bucket against the stop and watching what the peak pressure is. Of the top of my head, I can't remember which hose or cylinder they connect to or what the pressure is supposed to be, but I *THINK* it is a bit higher than 2200 PSI. I can check later this weekend if you want (I am out of town right now).

Michael

 

[wdchyd]

you can disconnect any hose from BH controls going to a cyl providing it's not one with a work port relief (that pressure will show up lower)......

 

[J_J]

There is a difference between cracking pressure, and full relief. The cracking pressure will be higher, and when the relief is fully open, the pressure will lower, and this is the pressure you want to adjust.

 

[wdchyd]

There is a difference between cracking pressure, and full relief. The cracking pressure will be higher, and when the relief is fully open, the pressure will lower, and this is the pressure you want to adjust.

I think you got it backwards JJ...
Kubota Flow/Load Meter Test - Tractor Videos - Kubota, John Deere, New Holland and More

This video shows it......cracking pressure is just when flow starts to bypass to tank......full relief shows higher pressure when dumping all flow to tank.....

Max pressure is at full relief

 

[J_J]

cracking pressure

The point at which the internal pressure of a hydraulic system triggers or actuates a valve. Also called the blow-off pressure.

It would seem to me that the initial pressure to move the poppet off the orifice would be greater that full open, which will release more fluid, and decrease pressure.

Perhaps you could explain further.

 

[woody]

yes sir, I think adjusting the fel prv with shims is the answer to my problem. need to know the max pressure and then I need to convince the dealer and Kubota rep to get R done, or I'll have to do it myself. it still bothers me that the service man told me it was 40psi over max and clearly it can't be.

 

[kennyd]

yes sir, I think adjusting the fel prv with shims is the answer to my problem. need to know the max pressure and then I need to convince the dealer and Kubota rep to get R done, or I'll have to do it myself. it still bothers me that the service man told me it was 40psi over max and clearly it can't be.

Can you describe exactly how you tested the pressure?

 

[J_J]

Yes, it could be set 40 psi over.

If the service man had a manual pump, he could pump up the pressure greater than pump pressure, adjust it to 40 psi over the tractor pump, and insure the relief for the valve never activates, or activate a cyl, and when the valve starts to relief, turn the screw some more, about a quarter turn. If it is shimmed , add shims to go beyond the pressure required to activate the valve.

If you have the gage, and you know the pump max psi, then you can adjust all the reliefs on the tractor the same, and be done with it. If you set them at pump pressure, that is the max pressure you will be using, and about the best you can do for the hydraulics.

Have you had the chance to operate another BH, with same pressure to determine if it has similar performance.

You don't need the service man now that you have a gage. You do have to know the pump rated pressure limit.

 

[woody]

JJ, thanks I have no not ran another b26 but I have ran similar BH. and your right I believe I will be making some adjustments myself.

 

[JoelD]

How is this not a warranty matter?

Can't you just google b26 relief presure and find what it should be at?

I'd first have fixed under warranty

Then I'd purchase service manual which answer many of your questions

The last thing I'd be doing is messing with a new machine (essentialy new)

Would hate break something upstream


Joel

 

[woody]

How is this not a warranty matter?

Can't you just google b26 relief presure and find what it should be at?

I'd first have fixed under warranty

Then I'd purchase service manual which answer many of your questions

The last thing I'd be doing is messing with a new machine (essentialy new)

Would hate break something upstream


Joel

Joel you are right but I have been tring to get two local dealers and a Kubota rep to take care of it.

 

[mrennie]

Hi:

The factory manual says to warm the hydraulic oil up to 50 degrees C, run the motor at rated RPM (2800), then attach a pressure gauge to the lower hose on one of the dump cylinders (they show a picture of the gauge connected to the hose that normally goes to the lower fitting on the left side cylinder that controls the bucket rollback/dump).

Once you connect the gauge it says to move the FEL control lever to the DUMP position and measure the pressure. Pressure should be 2290PSI-2400PSI.

If pressure is not within spec, adjust with shims. They list 3 shims thickness, .1MM, .2MM, and .4MM. There is no info saying how much change there is with the different thicknesses.

Hope that helps!!

Michael

 

[woody]

Hi:

The factory manual says to warm the hydraulic oil up to 50 degrees C, run the motor at rated RPM (2800), then attach a pressure gauge to the lower hose on one of the dump cylinders (they show a picture of the gauge connected to the hose that normally goes to the lower fitting on the left side cylinder that controls the bucket rollback/dump).

Once you connect the gauge it says to move the FEL control lever to the DUMP position and measure the pressure. Pressure should be 2290PSI-2400PSI.

If pressure is not within spec, adjust with shims. They list 3 shims thickness, .1MM, .2MM, and .4MM. There is no info saying how much change there is with the different thicknesses.

Hope that helps!!

Michael

Thank you, this is just what I needed I can live with 2400psi but the 2200psi that is right now is not going to get it. I think I need one of those manuals. thanks again to everyone.

 

[woody]

I have been calling Kubota in Georgia, three times in the past week. Today I got a phone call from my local dealer he wants my B26 in his shop Wednesday so the Kubota rep can look at it.

 

[J_J]

Make sure you demonstrate to the rep, what the BH will or will not do. Good luck

 

[J_J]

An increase of 2200 to 2400 psi will increase a 3 in cyl, 1.5 in rod, a cyl push force about 1200 lbs.

 

[JoelD]

Sounds like your are on your way to a solution, looking forward to seeing what the rep has to say.

I hope you get his resolved to your satisfaction.

One things for sure, the guys here sure do make it easy to get the information you need to be able to speak intelligently with the rep and dealer, makes resolution a lot easier to get at.

Those B26's are nice machines.

Joel