COMPONENT OPERTATION / Control Valve OUTLINE The control valve controls the pressure, flow rate and flow direction in the hydraulic circuit. The main control valve consists of two rows of 4-spool section and 5-spool section. The major parts are main relief valve, flow combiner valve and spools, and are operated by pilot oil pres- sure. As for the spools, in the 4-spool section of control valve, right travel, bucket, boom 1 and arm 2 are arranged in that order as viewed from the machine front. In the 5-spool section, left travel, auxiliary, boom 2, arm 1 and swing are arranged in that order as viewed from the machine front.
Swing Arm 1 Boom 2 5-Spool Section Auxiliary Travel (Left) Arm 2 Main Relief Valve Boom 1 Bucket Travel (Right) 4-Spool Section T1J1-03-03-010 T3-3-1