JLG 45HA Hydraulic Issue

[TheFixer]

I have a JGL 45HA. I capped the ports on the drive valve, and when operated one way, I can get it to the 3000 psi it should be. When I go the other way, it only gets to about 2400 psi. I swapped a valve cap end with a different function, and added shims to the spring, but no change.

The odd thing, is when I function another function, it will jump up to the 3000 psi, but not the drive function by itself.

I was curious if the dump valve could be causing this, but it seems like it is either open or closed. If it were leaking, it seems it would do it in both directions.

I ordered a seal kit for the valve, but was wondering if someone had some other insight. It seems it has to be internal to the valve.

 

[TheFixer]

Well, I figured out my issue. After taking the valve assembly out and rebuilding it, no luck.

Then after scrolling thru the Vickers technical manual for the valve, one of the cross section diagrams jumped out a me. It seems when you apply power to the solenoid, it pushed the spool away. Ok, sounds great. But after looking at the diagram, that means the pressure is then controlled by the pressure regulator on the opposite end cap of the valve. No where in Vickers or JLG manual call this out. The JLG manual ok, but I think this would be a big point to leave out.

I've worked on a lot of different types of equipment, but this is my first electric solenoid valve. I guess a good lesson learned.

So now, all the pressures are adjust and well. The swing doesn't quite get the 2200 psi from the platform, it gets it from the ground station, so I expect the controller needs adjusting. Not a big deal for now, swings fine.

On another note, since I was looking at my poor driving power, I pulled the cartridges out of the counter balance valve. One section had an o-ring cut and half missing. Maybe my brake was dragging. It did seam to be inconsistent.

I drove it after I reset the pressure, and much better. Haven't driven it since I rebuilt the counter balance valve.