HOW-TO-ADJUST (with pictures) Loader Relief Valve - Massey / Iseki / Challenger / etc

[TSO]

Finally located the pressure-relief valve for my Massey 1648. This should be the same valve-assembly for multiple tractors built by Iseki (for Iseki, Massey, Challenger, etc). Once located, I was finally able to check my relief PSI. My pressure was set at 2350psi, which was low - the manual states the loader relief is rated/tested at 2500psi.

Once I finally located this valve, adjustment was relatively easy. Access is the main opponent, as it is hidden pretty tightly in there. Also, the lock-nut (see pics) was seized to the bolt with factory paint, so the whole bolt needed to be removed to "un-seize" that lock-nut before I could adjust the set-screw.

I am excited to test the loader now with my salt-pallet test. Adjusting to proper specs amounted to a 6% boost in hydraulic pressure going to the loader, which in the case of my previous salt test (51 bags = 2,040 lbs) should increase the lift by 122lbs (up to 54 bags) --- IF there is a direct 1:1 correlation between the % of PSI and the units of weight that it can lift. But I'm not versed in the mathematics of hydraulic theory, so I don't know if that will be the case. I have also been hearing people suggest that it is "safe" to go 10% above the "rated" spec, which would put me at 2750psi ... so I might play with it a bit to find out what happens. I would assume that as long as I stay safely below 3000psi, which my hoses are rated to, I shouldn't break anything ... for limited testing scenarios. Anyhow..............

See pics for a "how-to"

 

[KenB2920]

Excellent post!!! Nice and detailed with photos!!! Great job TSO.

 

[J_J]

Why not install a tee in the IN port of the first valve and then run the gage to where you can see it while operating the tractor.

The gage can now be used for general operation and troubleshooting.

The gage will tell you when you have pressure and how much.

The beer is optional.

 

[Utopia Texas]

Why not install a tee in the IN port of the first valve and then run the gage to where you can see it while operating the tractor.

The gage can now be used for general operation and troubleshooting.

The gage will tell you when you have pressure and how much.

The beer is optional.

I see you are not using the official Orange Kubota clothes pins on your hydraulic hose cover!
Shame, shame, shame........

 

[J_J]

Shame on someone else as the picture is just a picture , not my tractor. .

 

[TSO]

Why not install a tee in the IN port of the first valve and then run the gage to where you can see it while operating the tractor.

The gage can now be used for general operation and troubleshooting.

The gage will tell you when you have pressure and how much.

The beer is optional.

I'm not worried about viewing it while driving... Only for diagnostics.

Anyone know the formula to determine the correlation between psi and actual lift strength? And, does the formula maintain consistency when the weights get higher?

For example, I turned my psi up 6% to get back to factory spec. But, I just did a pallet test and my lift strength on a pallet went up 17% !

If I turned it another 6% would I get an additional 17% lift?

 

[BXpanded]

I'm not worried about viewing it while driving... Only for diagnostics.

Anyone know the formula to determine the correlation between psi and actual lift strength? And, does the formula maintain consistency when the weights get higher?

For example, I turned my psi up 6% to get back to factory spec. But, I just did a pallet test and my lift strength on a pallet went up 17% !

If I turned it another 6% would I get an additional 17% lift?

Lifting the loader and attachments requires a certain amount of hydraulic pressure. This pressure is not available for lifting the load. If for instance, your system pressure is 2,500 psi and 1,000 psi is required just to lift the loader/bucket/forks, there is 1,500 psi available to do the work. If you raise the system pressure by 500 psi, there is now 2,000 psi available to do the lifting since the pressure required to lift the loader does not change. System pressure; 2,500 psi start, 3,000 psi after adjustment = 20% increase in system pressure. Available lift pressure, 1,500 psi start, 2,000 psi after the adjustment= 33.3% increase in lift. In this hypothetical scenario, a 20% increase in system pressure would provide a 33% increase in lift capacity.

Lift capacity should be linear IF working with the available lift pressure, NOT system pressure.
Example: Pretending in the OP's case, if 1,350 psi lift pressure (original 2,350 psi - 1,000 psi required to lift the attachment) will lift 2,040 lbs. of salt, 1,500 psi lift pressure will lift 2,267 lbs. (when the system pressure is adjusted from 2,350 to 2,500 psi.)

To calculate the effect, read the gauge while raising the empty loader/attachment. This is the loader lift pressure.
Read the max system pressure with the cylinders are fully extended. This is total system pressure.
Subtract the loader lift pressure from the system pressure. That is the pressure available for lifting.

Determine the max lift capacity (lbs. of salt). Divide the lbs. of salt by the available lift psi. This is the lift capacity for each psi of available hydraulic pressure.
Multiply this number by the psi CHANGE (i.e.: 2,350 psi to 2,500 psi=150 psi change) when adjusted. This is the expected increase in lift in pounds of salt.

NOTE that all numerical values used were chosen for ease of use and do not represent real values. Many other factors come into play such as the position of the load on the forks, lift height, gauge error, etc.

 

[DuckSlayer1017]

TSO, Thanks for taking the time to show that. I'll have to test my 1529 (in the spring).

 

[TSO]

BXpanded... Thank you for that information. I will have to do some more testing to get a baseline for what the loader actually weighs and how much psi is required to lift it by itself.

TSO, Thanks for taking the time to show that. I'll have to test my 1529 (in the spring).

No problem, my pleasure. I had a heck of a time trying to get the information, ended up using the scientific method and turned just about every bolt I could find near the valve to find the right one!

 

[J_J]

Actually the lifting ability changes as you raise the loader arms, as you are changing the angle of the cyl to the push point.

cyl at 45 degrees = 5554 lbs of push force.

cyl at 35 degrees = 4505 lbs of push force.

This is why some tractors can lift a certain weight off the ground, but can not raise it up all the way.

You decrease your lifting potential as you lift, based on the angle of the cyl., and then , where is the load position in relation to the bucket pins.

Have you ever noticed that by rolling/curling the bucket back, you are shifting the load point and can lift more, or fully raise the load.