Well the valve (IF available) is more than twice what I thought. The tear down and inspection of the valve did not uncover anything. All valves had their O-rings and seals. I did find an internal plug and sealed it. It was tight. All passage that were visible looked clear.
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450A Bang Bang functions not working
- Thread starter Donold
- Start date
I finally resolved the platform issues. In diagnosing the original problem the technician switched the swing and the tower cartridges. The swing dumps back to tank in neutral and the tower and telescope do not. I have adjusted the reliefs on the swing and I have good pressure at the block. I will make sure I do not have a restriction at the motor, today. (time permitting)
willie59
Administrator
Yes, that's the very kind of thing that is practically not possible to diagnose using the diagrams, like I stated earlier, I couldn't see anything on the diagrams that would allow what it was doing, but by swapping spool cartridges, well, things are no longer according to the diagrams. And it's a stretch to call the former wrench a "technician". Anyone who knows even a little bit about hydraulic valves knows that it's critical that spools go back in the holes they came out of and never allow them to get mixed up. Good to hear you've made some progress
autolodge
New Member
Wow, This is literally the identical problem I'm having. Bought the machine from a "mechanic" that tried diagnosing main boom not coming down. Like Donald I have Tower up/dn, swing, drive and steer but nothing else. On my P1 circuit I have 230 psi at the test port whether I run the gear pump or auxiliary power unit. I have tested all voltages and grounds at the coils, removed and inspected valves for actuation and run though the limited "troubleshooting" page with tests in the JLG 450aj manual. My machine is serial 56xxx with the ford EFI engine. Looking at the valve/coil cartrages, Swing, Upper Lift, Tower, and Telescope all have wrench marks on them. I suspect parts swapping put me in the same boat as Donald. Is there any way to inspect the tip of the valve to see if it is a flow through or not? Pulled the dump valve and proportional flow valve to check operation so I have an Idea of what I'm looking at. Is there another way to check that the valves are correct?