L/O Box is "lockout box" Inside are your relays for your function controls. It is located just to the fork side of the SCR panel.
A solenoid valve is an electromagnetic valve that opens and closes; in this case allows (open) and shuts off (closes) hydraulic pressure flow depending on selection from the operator controls.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.