Popular Science: Principles and Basics of Excavator Hydraulic System

The hydraulic system is the core of an excavator, equivalent to the "bloodstream" of the human body. Its performance directly determines the excavator’s working efficiency, operating feel and reliability.

An excavator hydraulic system mainly consists of a hydraulic pump, control valve, hydraulic cylinder, hydraulic motor, pipelines, oil tank and other components. The engine drives the hydraulic pump to rotate, converting mechanical energy into pressure energy of the hydraulic oil. High-pressure oil is delivered to the main control valve through pipelines. When the operator operates the control handle, the main control valve distributes the pressurized oil to the corresponding hydraulic cylinders or motors according to the command, realizing movements such as boom lifting and lowering, arm telescoping, bucket digging, slewing and traveling.

At present, mainstream excavators adopt negative flow control or load-sensitive control systems. The load-sensitive system can automatically adjust the output flow of the hydraulic pump according to the actual load demand, avoiding overflow of excess flow, thus reducing fuel consumption and improving operation smoothness. This is the key reason why new-generation excavators are more fuel-efficient and operate more smoothly than old models.

As the medium for power transmission, hydraulic oil must have good wear resistance, oxidation resistance and anti-foaming properties. Hydraulic oils of different brands and grades cannot be mixed, otherwise chemical reactions are likely to occur, resulting in oil deterioration, valve core jamming, seal aging and other failures.

In daily use, keeping the hydraulic oil clean is critical. Dust, moisture and metal debris from the air entering the hydraulic system are the main causes of early wear of pumps, valves and cylinders. Therefore, replacing the hydraulic oil filter element on time, keeping the tank vent unobstructed, and avoiding disassembling pipelines in extremely dusty environments are effective ways to extend the service life of the hydraulic system.