Method for improving excavating operation characteristic and grading operation characteristic of excavator

A method for improving excavating operation characteristic and grading operation characteristic of an excavator including a boom, a stick and a bucket, the method comprising:

• receiving a control signal by a solenoid valve group (4) that controls both a boom confluence control circuit and a stick confluence control circuit for controlling a confluence for the stick, such that:
• the solenoid valve group (4) switches between a disconnected mode and a connected mode, and the excavator switches between an excavation operation and a grading operation;
• performing the excavation operation, when the solenoid valve group (4) is in the disconnected mode to restore a boom lifting confluence circuit, and to disconnect a stick swinging confluence circuit;
• detecting a control pressure value of a stick excavation by a hydraulically controlled selector valve (7) configured in the boom confluence control circuit for controlling the boom of the excavator;
• and
• when the control pressure value of the stick excavation reaches a change-direction pressure of the hydraulically controlled selector valve (7) to change a direction, disconnecting the boom confluence control circuit but independently supplying oil to the boom by an additional single pump, while the double pump confluence circuit is only used for the stick excavation.