Flow Rate Control Valve - Hitachi ZW180 Technical Manual

FLOW RATE CONTROL VALVE

The flow rate control valve is installed in the bucket
circuit, restricts the circuit during the combined
operation and gives priority to operations of the other
actuators.
Single Operation of Bucket Crowding
1. Pressure oil from the main pump flows through
the lift arm spool.
2. Pressure oil from the lift arm spool flows to the
bucket spool through check valve 1 and is
supplied to the bucket cylinder.
COMPONENT OPERATION / Control Valve
Inlet of Pressure Oil from
Main Pump during Lift
Arm Spool Operation
To Bucket Spool
Combined Operation of Bucket Crowding and Lift
Arm Raising
1. One of pressure oil from the main pump is
supplied to the lift arm cylinder through the lift arm
spool.
2. Another of pressure oil from the main pump is
supplied to the bucket spool through the parallel
circuit.
3. At this time, pressure oil is restricted through the
orifice from check valve 2.
4. Pressure oil through the orifice flows to the bucket
spool and is supplied to the bucket cylinder.
5. Therefore, as pressure oil to the bucket spool is
restricted and more pressure oil is supplied to the
lift arm side having higher pressure, both the lift
bucket and the lift arm move at the same time.
Check
Valve 1
Inlet of Pressure Oil from
Main Pump in Neutral of Lift
Arm Spool
T3-2-22
Check Valve 2
Orifice
T4GB-03-02-020