Hydraulic excavator mainly consists of engine, hydraulic system, working device, walking device and electric control. The hydraulic system consists of a hydraulic pump, a control valve, a hydraulic cylinder, a hydraulic motor, a pipeline, an oil tank, etc. The electrical control system includes monitoring panel, engine control system, pump control system, all kinds of sensors, solenoid valves, etc.
Hydraulic excavators are generally composed of three parts: working device, rotary device and walking device. According to its structure and use, it can be divided into three types: crawler type, tire type, crawler type, full hydraulic, semi hydraulic, all rotary, non full rotary, general type, special type, articulated type and telescopic arm type.
The working device is a device for directly completing the excavation task. It is articulated by three parts, such as boom, bucket and bucket. The take-off and landing of the boom, the expansion of the bucket rod and the rotation of the bucket are all controlled by reciprocating double acting hydraulic cylinders. In order to meet the needs of various construction operations, hydraulic excavators can install various working devices, such as mining, lifting, loading, leveling, pliers, pushing soil, impact hammer and so on.
The rotary and walking device is the body of the hydraulic excavator, and the upper part of the turntable is equipped with a power device and a transmission system. The engine is the power source of the hydraulic excavator. Most of the diesel oil is used in the convenient field, and it can also be switched to motor.
The hydraulic transmission system passes the engine's power to the hydraulic motor, the hydraulic cylinder and other actuating components through the hydraulic pump, and promotes the operation of the working device, thus completing various kinds of operation. Take the PV-200 hydraulic excavator which is used more frequently at the construction site as an example. The improved open center load sensing system (OLSS) is adopted. The system reduces the power output of the engine and reduces the fuel consumption by controlling the angle of the skew disc of the inclined disc type variable plunger pump, thus reducing the fuel consumption. It is an energy-saving system.
The hydraulic system is characterized by constant torque control, which can maintain the constant driving torque of the hydraulic pump and control the load. It can reduce the unloading loss of the working time; the oil quantity control can reduce the output flow of the hydraulic pump and reduce the loss of power.
