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10 Structure, function and maintenance standard
11. Swing assurance function
•
During compound operations with the arm and swing or with the bucket and swing, the throttle valves in the
arm and bucket circuit ensure the flow of oil to the swing circuit in order to assure ease of compound opera-
tions.
Operation
•
If the swing PPC pressure goes above 1.5 MPa {15 kg/cm
or more), the swing assurance selector valve is actuated and the swing drive pressure locks the pilot check
valve of the 5-spool valve arm and bucket throttle valves.
•
In this condition, the circuits are in parallel, so the oil from the 5-spool valve flowing to the arm or bucket is
throttled by the throttle valve, so the swing drive pressure rises. In this way, the swing drive is assured.
PC800, 850-8
} (the control lever is operated approximately half
2
SEN00386-03
37
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