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The Hydraulic System
The hydraulic system serves as the foundation for various movements and automatic control functions of the excavator. In a way, the performance of the hydraulic system determines the quality and operational efficiency of the excavator.
Modern excavators can automatically switch between variable power modes and full capacity depending on working conditions and the environment. This ensures that the engine is not overloaded, allowing smooth operation and optimal power utilization.
Additionally, features like the Auto Slow system and the Negative Control system reduce engine RPM and minimize hydraulic pump displacement when the working device is idle, saving energy.
Given the rapid and significant changes in the working conditions of excavators, modern excavator control systems should include the following features to ensure efficient use of engine power, safety, and proper operation:
Speed Sensor
- Ensures the engine’s speed is within the output range.
- Controls the drive torque of the hydraulic pump to match the engine speed.
- Prevents engine stalling.
Load Sensor
- Adjusts hydraulic pump displacement according to the flow requirements of each actuator (e.g., boom and bucket cylinders) during operation.
- Saves energy and enables precise machine control.
Flow Distribution Control
- Provides different pressures and flows for each actuator (e.g., boom cylinder, bucket cylinder) to ensure coordinated movement of working devices.
- When the hydraulic system has only one main pump, flow distribution control allows simultaneous operation of each actuator to meet varying work demands.
Work Mode Selection
- Meets the requirements of various work modes, including digging, trenching, leveling, and precision movements.
Drive Motor Control
- Includes systems for automatic speed selection (high, medium, and low).
- Allows the machine to adjust travel speed according to external load and control lever position.
Swing Parking Brake Control
- Prevents the upper structure from rotating under gravity when the machine stops.
- During operation, the swing parking brake activates a few seconds after the control lever is returned to the neutral position to avoid damage from chronic rotational forces.
Preheating
- When the hydraulic oil temperature drops below a specific threshold, the engine speed automatically increases, and hydraulic flow rises, quickly warming up the hydraulic system.
Emergency Power Boost
- Applying back pressure to the main safety valve raises system pressure to temporarily increase working power.
Achieving these functions is closely linked to the control of the hydraulic system.
