Most of today's excavators are full hydraulic rotary excavators. Hydraulic excavators are mainly composed of engine, hydraulic system, working device, walking device and electrical control. The hydraulic system is composed of hydraulic pump, control valve, hydraulic cylinder, hydraulic motor, pipeline, oil tank, etc. the electrical control system includes monitoring panel, engine control system, pump control system, various sensors, solenoid valves, etc.
Hydraulic excavator is generally composed of working device, rotary device and walking device. According to its structure and use, it can be divided into crawler type, tire type, walking type, full hydraulic, semi hydraulic, full rotary, non full rotary, general type, special type, articulated type, telescopic arm type and other types.
The working device is a device that directly completes the excavation task. It is hinged by three parts: boom, stick and bucket. The rise and fall of boom, the expansion and contraction of stick and the rotation of bucket are controlled by reciprocating double acting hydraulic cylinder. In order to meet the needs of various construction operations, the hydraulic excavator can be equipped with a variety of working devices, such as excavation, lifting, loading, leveling, clamp, bulldozer, impact hammer and so on.
The slewing and traveling device is the body of the hydraulic excavator. The upper part of the turntable is equipped with a power device and transmission system. The engine is the power source of the hydraulic excavator. Most of them use diesel. In a convenient place, they can also use a motor.
The hydraulic transmission system transmits the power of the engine to the hydraulic motor, hydraulic cylinder and other executive elements through the hydraulic pump to promote the action of the working device, so as to complete various operations.
1、 The engine has sufficient power, but the vehicle is stuffy (suffocated).
The hydraulic pump itself also has a certain power. If the power of the hydraulic pump is greater than that of the engine, there will be a phenomenon of stuffy car (holding car). This requires the hydraulic pump to be tested and debugged on the test bench, and the power of the hydraulic pump can be reduced to 95% of the engine power.
2、 Walking deviation, and the action of one handle is not ideal.
The hydraulic pump can be divided into front and rear pumps or left and right pumps. Running deviation indicates that one pump has a fault. The simplest way to judge is to remove the two high-pressure oil pipes of the hydraulic pump and adjust them. If the original slow walking becomes faster and the fast walking becomes slower, it indicates that one pump has a fault. The excavator can repair the problems in such cases by removing the hydraulic pump, processing or replacing the accessories in one pump, and then debugging on the test bench, At the same time, it also solves the problem that one handle is not ideal.
3、 The engine has sufficient power and operates normally, while the machine is slow and unable to dig.
1. The hydraulic pump of the excavator is a plunger variable displacement pump. When it works for a certain time, the components in the hydraulic pump (cylinder block, plunger, port plate, swing, etc.) will inevitably be excessively worn, resulting in a large number of internal leakage and uncoordinated parameter data, resulting in insufficient flow, high oil temperature, slow speed and unable to establish high pressure, so the action is slow and the excavation is weak. For such problems, the hydraulic pump must be removed, Send it to the commissioning Department of the company to test the data of the hydraulic pump, confirm the problem of the excavator, replace the parts that can not be used, repair the parts that can be used, reassemble the hydraulic pump, and then go to the commissioning test bench to match various series of soft parameters (such as pressure, flow, torque, power, etc.).
2. At the same time, the excavator also has an important hydraulic component multi-channel distribution valve, which is equipped with excavator repair shops such as main safety valve, secondary valve, jet valve and oil make-up valve. If the pressure set by these safety valves does not reach the standard pressure (the standard pressure of ex200-5 main safety valve is 320kg, while the current pressure is only 230kg), the excavation will be weak. In addition, if the clearance between the valve rod and the valve hole is too large due to wear, and the valve rod return is incomplete, It will lead to insufficient flow and slow speed. For such problems, it is necessary to remove the multi-channel distribution valve, directly raise the test bench for commissioning after sending it to the company, reset the pressure of all safety valves and eliminate the gap between the valve stem and the valve hole.
3. The hydraulic pumps on the excavator are equipped with pilot gear pumps, which are mainly used to participate in the variable of the hydraulic pump and open the valve rod of the multi-channel distribution valve as the pilot oil to make it reverse. If the gear pump is excessively worn and can not establish a certain pressure or the pressure set by the safety valve on the gear pump is not enough, the hydraulic pump will always be in a low flow state and the valve rod can not be completely reversed, so the flow will be insufficient and the action will be slow, The pressure is not enough and the excavation is weak. For such problems, just replace the pilot gear pump or reset the pilot safety valve.
