Our JLG 1200 is making a screeching/ whistling sound right after you stop retracting the boom. It sounds like its coming from inside the boom but i cant pinpoint exactly where. My guess is its something hydraulic related like air in the system. My questions would be how to get rid of this noise? I will mention that we had to replace the holding valve on the back of the extend cylinder last week....but this noise was happening before this was replaced. Any ideas?
Anyone have ideas?
Just an idea but could the whistling be hydraulics bypassing? Maybe on a cylinder or hydraulic manifold with a lock valve, orifice, or counterbalance valve bypassing? Best would be to pinpoint where the noise is coming from and from what function then check hydraulic diagram and see what could be failing in that system. I've had that happen on a few machines with the block located on the jib, usually something simple like a valve that is bypassing hydraulic pressure instead of holding. GL.