Hydraulic excavators are mainly composed of engine, hydraulic system, working device, walking device and electrical control. The hydraulic system consists of a hydraulic pump, a control valve, a hydraulic cylinder, a hydraulic motor, a pipeline, a fuel tank, and the like. The electrical control system includes a monitoring panel, an engine control system, a pump control system, various types of sensors, and solenoid valves.

    The hydraulic excavator generally consists of three parts: a working device, a rotating device and a running device. According to its structure and use, it can be divided into: crawler type, tire type, walking type, full hydraulic, semi-hydraulic, full rotation, non-full rotation, general purpose, special type, articulated type, telescopic arm type and so on.

                                                      

    The working device is a device that directly performs the excavation task. It is hinged by three parts: boom, stick and bucket. The boom landing, the stick telescopic and the bucket rotation are all controlled by a reciprocating double-acting hydraulic cylinder. In order to meet the needs of various construction operations, hydraulic excavators can be equipped with a variety of work equipment, such as digging, lifting, loading, leveling, clamping, dozing, impact hammer and other work tools.

    The swing and travel device is the body of the hydraulic excavator, and the power unit and the transmission system are arranged on the upper part of the turntable. The engine is the power source of the hydraulic excavator. Most of the diesel is used in a convenient place, and the electric motor can be used instead.

    The hydraulic transmission system transmits the power of the engine to the actuators such as the hydraulic motor and the hydraulic cylinder through the hydraulic pump, and pushes the working device to perform various operations. Take the PV-200 hydraulic excavator with more construction sites as an example. The machine uses a modified open center load sensing system (OLSS). The system uses an swash plate type variable displacement piston pump swash plate angle (output flow rate) to reduce the power output of the engine and thereby reduce fuel consumption. It is an energy-saving system.