I’ve transplanted the entire hydraulic system from a ZX50U-2 into a different machine. I’ve followed the drawings as best as I can. When I fire it up, I get very little pressure—cylinders barely move in the pin clearance and it can’t lift any weight. I want to confirm exactly what lines or pilot feed should connect to the main relief valve. Any guidance on correct plumbing or what could restrict pressure would be appreciated!
My first guess is your unload valve in the main control valve is open and returns the flow from the main pump to the tank. If so you will measure 0,3MPA of pressure in the main pump. If the unload valve is open I dont know why right now. If the main pumps A/C power decrease pc line is not used it has to be connected to the tank. Pilot pressure and PLS pressure is connected to the main control valve. PLS pressure can only lower the pump power, not rise it. Maximum pump power is regulated by the internal spring in the pump. If you disconnect the PLS pressure from the PS valve on the pump and connects the PS valve PLS connection to the tank the power of the pump will be 100%.
Thanks kjell, I just ran a couple tests, I removed the plug from the pc line and disconnected the PLS line from the pump which had no change on the way it reacted. To confirm the three ports on the control valve next the the main inlet 1,tank return 2,PLS line and the one next that goes to the centre port on the double solinoid valve. Cheers
Hi Kjell, I tested my pressure on the pilot which was 750psi at idle and main pump line was 200psi. Any ideas
I've fixed it!!!! Apparently you need pilot pressure to the relief valve not a tank drain.