On a 590 turbo (similar to 580k), it runs and front loader operates but the back digger doesn’t. If you swing it to the left or to the right the boom and dipper has full power but if swing cylinders aren’t engaged then all rear hydraulics are only 1/4 of power. Any ideas what would be causing this problem?
Hello, I also have a 590 turbo I’m rebuilding. There are many oddities to the open-center hydraulic design. I have also experienced where sometimes activating a backhoe function with something else accelerates the backhoe actuator (although not a 4x speed up per your prior post). A few ideas / questions: 1) are you bottoming out the swing cylinder or any other cylinder when you notice the backhoe function take off? 2) have you checked your relief valve settings? There are separate relief valves for both the backhoe and the loader. 3) have you put a pressure gauge to any part of the hydraulic system? I’d look deeper into the backhoe spool, it’s at the very back of the machine, just under the cab and you’ll see a bunch of hydraulic hoses coming in and out of it.
The most likely cause is the regeneration spool sticking or anti cavitation spool sticking in the backhoe valve. If you are unsure of how to remove and check these I'd call a mechanic. They are under spring tension and if you are not careful you'll end up losing something.
Thanks for your response. The answer to question 1 is yes when the swing is bottomed out either left or right all of the rear hydraulics work normal even the outriggers.but only when the swing is held in motion To answer question 2. I have not checked any relief valve settings the loader and steering work like they should. I don’t know where the relief valve for the backhoe is located. To answer question 3. I have not put any pressure gauge on any of the system. We did put a complete valve body off of a 580 super K and nothing changed?? The K was a working machine when it was parted out