Good morning fellows, Some years ago I bought what I thought it was an almost worn out Fiat-Hitachi for opening a quarry. After 9 years the machine is still giving its fight and I am trying to refurbish it new. My first problem is that I don't know exactly the manufacturing year, maybe someone can help me with this issue. There is a serial number outside the cabine 22H0063 M. . The second issue is when I start lowering the boom, I can't make smooth / controlled movement, the boom goes down too fast. The boom cilinder doesn't go down when the machine is stopped, so the seals are OK. They doesn't leak at all. I would really appreciate some help, best regards, Pablo
Hello there you all, Yesterday I finally found the uncontrolled boom's movement when going down. It was a faulty spool into the joystick's pilot valve. Now working on fixing that problem, maybe it was wrongly assembled when the mechanic replaced its internals. I came into account that the problem was the pilot valve, cause when reading the Fiat Hitachi owner manual (it is almost a Hidraulic engineering carrer!, so detailed!) it showed some graphics whith the curve of response to the joystick movement, and that was not happening! I swapped hose possition into the pilot valve and Hey presto! the boom going down so slowly you can pour milk into your coffee! best regards, Pabo
This is how does the pilot valve works