why you have to check those hyd pressures on a new tractor

[dfkrug]

Just got another new tractor.

As is my habit with any piece of equipment I get, I thoroughly checked it
out. I found one FEL bolt that was barely started and a hydraulic
pressure test that showed 3000psi at the loader! This means that either
the FEL relief valve is at 3000 and the system RV is the same or even
higher. Or vice versa.

You can not count on the dealer to check those settings! Spec for this
Bobcat CT230 is 2611psi.

 

[MtnViewRanch]

Maybe they crank it up to handle that 68" over sized bucket that they come with.

 

[carpenter383]

Just got another new tractor.

As is my habit with any piece of equipment I get, I thoroughly checked it
out. I found one FEL bolt that was barely started and a hydraulic
pressure test that showed 3000psi at the loader! This means that either
the FEL relief valve is at 3000 and the system RV is the same or even
higher. Or vice versa.

You can not count on the dealer to check those settings! Spec for this
Bobcat CT230 is 2611psi.

Wowsers My kioti was at about 2700 psi and I thought that was a little iffy. (I left it alone though)

 

[IceStationZebra]

1. Sometimes the relief poppet needs to "seat" with the poppet seat due to manufacturing tolerances. I was told by a respected valve engineer to roughly set the relief, hit the relief about 10 times, then do a final adjustment.

2. Relief settings almost always change with hot vs. cold oil. Should be checked with oil at least 90°F.

3. Relief settings can change depending on flow (ie engine speed) due to flow forces around the poppet. I normally check at full throttle because that is were it will be used.

The other observation is are you sure the gauge is accurate? I went through the gauges at work last year and just about every one was at least 50psi off, some much more. I threw about 20% away because they were so far off. Any time you spike the needle you risk damaging the bourdon tube inside, which throws the readings off.

ISZ

 

[J_J]

You have the cracking pressure which starts to open the relief, and then you have the full relief pressure. The cracking pressure will be higher. It should be relieving fully while you are adjusting.

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

full-flow pressure The point at which a relief valve is diverting flow at its maximum rate.

 

[dfkrug]

The other observation is are you sure the gauge is accurate? I went through the gauges at work last year and just about every one was at least 50psi off, some much more.

I do not disagree with any of your points, ICE. It is one thing to be off by
50 psi, but to be 400psi high? And don't forget that this means TWO
RVs have to be at least 3000 psi. That's a serious oversight at the factory.
Bobcat dealers get their tractors from N Dakota already assembled and
mine does not check pressures. I will check the system RV separately in
a day or so.

BTW, my guage is glycerine-filled, but not really calibrated here. I have
used it a lot and it has given readings in expected ranges for the tests I
do on tractors, hoes, and AUX valves. I will compare it next time to another
guage I have. If it is as much as 50psi off, that's OK.

 

[dfkrug]

I reset my FEL valve to about 2700. I can see that the valve was set
before it was painted. The dealer said he was going to contact the
folks up in Fargo.

I can not find where the main hyd system "safety valve" is...the manual
does not say.

 

[J_J]

If you follow the pressure hose to the first valve block, you should be close to the relief valve for the pump. Both valves in this illustration have reliefs at the input to the valve.

http://www.baumhydraulics.com/files/infobuild/basic_hydraulic.pdf