Hitachi ex55ur gray market machine ...Problem in the stick cylinder circut ( i think hitachi calls it the Arm cylinder) .No electric solenoids just pilot oil ... Arm cylinder will be extremely slow on the curl side ..I swapped hoses at the valve and the problem moved to the extend side ..therefore I feel the cylinder it self is ok ..I then swapped pilot oil cicut and problem stayed on the extend circut .. I took the spool out of the valve and was pretty tight in the the bore ..Papered the valve and cleaned the bore put back together and same thing ....I then pulled the whole vale body out of the stack valve and took it apart ..not seeing anything obvious .. The bad thing is by the Hitachi parts break down there is no part # for the housing (of course nobody is working today so really cant do more research on the housing) ...I was wondering if I should swap this valve pack with one from say the boom valve and see if i move my problem there ??? Anyone have any problems like this ??
Secondary reliefy valve Are there two secondary relief valve mounted on the arm section of MCV? If yes, please exchange them to check if the problem changed sides, if changes, you can use the relief valve on the boom section, I think they might be the same to double check it.. Cause as you said cylinder is okay, no other operation encountered slow problem, so pump is okay. And spool you checked, normally it happened about the secondary relief valve.probably the spring against the safety valve getting wear. Good luck..
Thanks for the reply ....To my knowledge theres no secondary relief vavles in that circut ..I have traced the lines from the cylinder back to the valve .. I m hoping to get another valve about the first of next week ....I'll find out then .. If your talking about the relief valves in that section ..When I swapped pilot oil it would have moved the problem to the other side ..