Chapter A
Chapter A
Components of AML System
1
W301-0411E
A-1 Components of the AML System
1.1 System configuration
1.1.1 Diagram of the Main System
1. Load
moment
ratio
≥
100%
AML vent / compulsory unload of the main relief valve.
٠
If an overload occurs, the AML stops the 24-V output from Do1. Thus the solenoid valve for VENT is
returned to neutral by the spring and vents the oil in the spring side of the balance piston in the main-circuit
safety valve into the tank circuit. The whole oil discharged by the pump is unloaded into the tank, making
crane operation toward critical sides impossible.
٠
When crane operation toward non-critical sides (hoisting down, boom raising, boom retraction) is detected,
no oil is vented from the safety valve into the tank. Thus the crane operation becomes available.
2. Anti-twoblock (overwind) stop
:
If operation toward critical sides (hoisting up, boom lowering, boom extension) is attempted while the hook
block is over wound, 24-V output from Do1 stops. Thus the crane operation toward critical sides becomes
impossible due to AML vent (compulsory unload) in the same way as overload.
When operation toward non-critical sides is detected, the operation becomes available.
3. Backward stability stop:
When the boom is raised over the specified angle, the output from Do1 stops and the crane operation stops
automatically due to AML vent. Recovery from the automatic stop is possible only by boom raising.
4. Working range limit stop:
When the boom head approaches a pre-registered limit of the working range, slow stop function works and
the AML energizes the corresponding proportional solenoid valve. It slowly closes the pilot pressure circuit
for the main control valve to decelerate crane operation until the main control valve becomes neutral and
the output from Do1 stops to make AML vent disable crane operation. For swing limit, however, the
proportional solenoid valve makes the main control valve immediately to stop the crane. In this case the
crane does not swing beyond the limit even if the AML override is activated, and it swings only toward within
of the limit.
(Overwind detector)
(Overwind)
