Because the loader valve feeds the 3 pt and rear remotes, the rear relief valve has no affect when the loader calls for pressure to raise the arms etc.Isn't it possible for a 3 pt relief valve being faulty causing hyd problems?
However, the loader relief valve will limit what pressure the rear of the tractor gets. For example, if the loader relief is set at 2,000 psi, nothing you can do to the rear relief valve can make the rear pressure higher than 2,000 psi.
Why it is confusing is that the tractor WSM, when describing setting the relief valve pressure, makes no mention of the loader so if you have a loader it is confusing if you find the rear 3 pt pressure low. You need to also have the FEL WSM. But it makes no tie in to the effect its relief valve can have on the main tractor relief.
Dave