SYSTEM / Hydraulic System Valve Control Circuit (Refer to the Control Valve group / COMPONENT OPERATION.) The following valves are shifted by primary pilot pressure from the pilot pump, secondary pilot pres- sure from the pilot valve, solenoid valve units (SG, SF, SC), flow combiner valve spool in signal control valve and arm flow rate control valve control spool. Pilot pressure from pilot pump: Boom anti-drift valve and arm anti-drift valve Attachment pilot pressure (optional): Bypass shut-out valve (4-spool section) Solenoid Valve Unit SG: Main relief valve Solenoid valve unit SF: Boom flow rate control valve (switch valve) Solenoid valve unit SC:
Boom overload relief control valve Flow combiner valve spool: Flow combiner valve Arm flow rate control valve spool: Arm flow rate control valve (switch valve) T2-4-8