I am working on a 60H and all proportional controls I can only get 1000psi on test gauge. The engine rpm seems to work as it should, I can turn on high flow pump and high engine rpm and get pressure up to around 1500 -1800 psi. The bang bang functions work as they should. I have the 12v pump removed for repair. I have switched pump with bang bang pump and main pump will produce 2500 on bang bang function so have ruled out pump. The dump valve, relief, pilot and sequence valve are the latest all in one version from JLG. I have adjusted pilot and sequence to proper pressure. I checked the dump valve, and it closes and have replaced the main relief valve. It seems like something is overriding the dump valve and sending fluid back to tank. It has the Vickers control valve. The previous owner had all wheel motors and pump replaced 10 years ago because it wasn't traveling correctly and said haven't used it a lot since.
Thinking possible contamination in the Vickers valve just didn't want to dissemble it if I was missing something somewhere else.
What problem are you chasing? Is it an all over lack of function or function speed? Or is it just certain functions? When you removed the 12V aux pump for repair, did you join the two hoses together or dead-end each one?
I can only get 1000psi on proportional controls it will jump to 1500psi when high pump is energized and little higher if high rpm, so when trying to boom up it will slightly move ,turn on high pump moves slowly turn on high rpm it moves ok. The drive behaves the same. I blanked the 12v pump lines to keep pump circuits separate.
I have installed a new pq controller for boom up, it behaves like the old one. I have not tried the adjustments yet as I don't feel I'm getting proper pressure
Here some info - the procedure for setting hyd. pressures.
Have tried those adjustment and can't get pressure to adjust past where the are. I am starting to think I have something stuck in the Vickers valve dumping my flow back to tank or causing back pressure on the dump valve causing it to dump back to tank?
Do you know if this is a load sensing pump system?
It's a triple gear pump on for proportional controls on for bang bang functions and a third for auxiliary flow
View attachment 20230312_153621.jpg This is the valve in my lift I think JLG rebuilt the unit in 2004 with updated valves
Found my problem took the sequential vale apart and the internal spring was crushed replaced it with a new one and now have full pressure
I was going to say check the sequencing valve as that valve determines pressure to the Vickers proportional valve but you stated you replaced it in your first post, which left me stumped. But, glad to see you backed up and said, OK, let's go through this **** again from the beginning. Sometimes that's what it takes and just like that you find your problem.
Crazy thing was I was able to set it to the proper pressure, I finally just disassembled the valves and found the spring, every loop was broke.