I hate to tell you that is not correct. Once the spool is centered it is the same as if the hoses were capped. No way for the relief to do anything for the loader hoses and cylinders. In an open center valve that utilizes the power beyond feature then any valve after the loader valve would be protected by the loader relief. Often times the loader valve is first valve in series and would be plumbed straight from the pump. The tractor relief is after the loader and can be set lower to release before the loader valve.
You could set the second valve to 100 psi and the loader would still produce the pressure that it’s relief is set at.
No. My post is completely correct in how my hydraulic system works (and that's the one we're talking about here since the OP has the same system), and it's how most--if not all--modern open-center hydraulic systems work.
Lets sort two things out:
1. Main relief valve is located immediately after the main hydraulic pump, in the transmission-mounted hydraulic block. Not after the loader valve.
2. Power-Beyond (PB) port in the loader valve has nothing to do with what we're talking about here. Forget about it.
Ok, so the loader valve spools, once in the neutral position, have separated the hydraulics into two circuits:
1. The main system hydraulics, which are still running and cycling fluid at almost zero pressure since this is an open-center system.
2. The loader circuits, where all ports are closed and the hydraulic pressure is relative to whatever weight is on the cylinders.
The loader circuits pushing back against the spools, are also tapped to a pressure relief valve, mounted on the loader block. If the pressure in any cylinder circuit exceeds 2610psi, the
loader relief valve opens and sends that fluid down the Return line, back to the hydraulic sump or tank.
Honestly that's as straightforward as I can make it. If you still don't understand how the system works, Google it or go to Youtube since a picture or video is going to be way more helpful to you.