COMPONENT OPERTATION / Control Valve FLOW RATE CONTROL VALVE The flow rate control valve is provided in the boom and arm circuits, restricts oil flow rate in the circuit during combined operation, and gives priority to other actua- tors. (Refer to the Control System, Hydraulic System groups / SYSTEM.) Each flow rate control valve is operated during com- bined operation as shown below. Flow Rate Control Valve Combined Operation Boom Boom Lower + Arm (Roll-Out / In) Boom Lower + Bucket (Roll-In / Out) Arm Boom Raise and Arm Roll-In NOTE: The boom flow rate control valve is ex- plained here. Normal Operation 1.
Pressure oil which flows to the 4-spool section parallel circuit from pump 1 is divided into the two directions. 2. One acts on the check valve A in the poppet valve. The other pushes to open check valve B and acts on the switch valve. 3. In normal, as the switch valve is kept closed, pressure oil from pump 1 is blocked by the switch valve. 4. Pressure oil from pump 1 pushes to open check valve A and the poppet, and flows to the boom 1 spool. Boom Cylinder To Boom 2 Spool Pressure Oil from Pilot Pump Poppet Switch Valve Pressure Oil from Pump 1 (Parallel Circuit) T450-03-03-046 T3-3-36