Hi all Looking for technical manual for a Hitachi ZX55U-5A, machine is very slow on all movements and I just want to see what way the LS system is done on it. Or if anyone has come across this issue before maybe you can shed some light on it. When I remove LS line off the control valve there is nothing coming out of it with levers pulled or not , still nothing.
The ZX55U-5A control valve inlet section is the same as a Deere 50G. Check if the orifice (item#23 in parts screenshot below) is plugged. Also if necessary check if the inlet strainer (item #10) is plugged. . The PLS oil passes through the orifice before exiting at port 41 to the delivery flow rate valve on the hydraulic pump. See screenshot from theory of operation. .
ZX55U-5A hydraulic schematic screenshot below.