Maintenance of Hydraulic System For mechanical construction companies, whether the construction machinery technology status is good or not is a direct factor in the normal production of the company. Today's construction machinery mostly uses electromechanical-hydraulic integration. The normal operation of the hydraulic system is a major indicator of its good technical condition. Qualified and clean hydraulic oil is the guarantee for reliable operation of the hydraulic system. Proper maintenance is fundamental to the reliable operation of hydraulic systems.

 

The hydraulic system is only well-maintained to allow the construction machinery giant to move freely

 

Hydraulic drive technology penetrates into all modern engineering fields. Compared with mechanical transmission and electric drive, hydraulic transmission has unique advantages: (1) Under the same volume, the hydraulic drive produces more power than the electrical device: (2) In the case of the same power, the hydraulic transmission device is small in size, light in weight, and compact in structure; (3) The hydraulic transmission has stable quality, high mechanical efficiency and good low-speed load characteristics.

 

However, due to the friction loss and leakage loss, the hydraulic transmission system has a large energy loss; it requires a relatively high degree of cleanliness of the oil, and requires regular replacement; changes in the oil temperature will affect the speed control and noise and other shortcomings. In addition, construction machinery is often exposed to mud and dust in outdoor work, under wind and rain. The operating load is often variable and accompanied by vibration, and the operating speed is often transient and inertial. Therefore, the hydraulic system of construction machinery should have special requirements: it should have good environmental adaptability and reliable closedness; it should have higher working reliability and the ability of sensitive real-time strain; it should have better maneuverability to make the system Closed and able to do a variety of changes. Therefore, when using hydraulic systems, we should follow the relevant procedures.

 

1, choose the right hydraulic oil

 

Hydraulic oil plays a role of transmitting pressure, lubricating, cooling, and sealing in the hydraulic oil system. The improper selection of hydraulic oil is one of the main reasons for the early failure and durability of the hydraulic system. The hydraulic oil should be selected according to the grade specified in the random “operating instructions”. When special oils need to be used, the performance should be the same as the original grade. Different brands of hydraulic oil can not be mixed to prevent the hydraulic oil from producing chemical reactions and changes in performance. Dark brown, milky, smelly hydraulic oil is a deteriorating oil and cannot be used. If you have used an oil device, when replacing it with other types of fluids, you must pay special attention to the cleaning of the device and the reliable replacement of the oil. It is best to use automated oil detection, cleaning, and replacement of the device.

 

2. The combination of active maintenance and regular maintenance of status monitoring complement each other

 

At present, some hydraulic systems for construction machinery are equipped with intelligent devices that have warning functions for certain hidden dangers of the hydraulic system, but are mainly used for the monitoring of key parameters. Therefore, the inspection and maintenance of the hydraulic system should combine the monitoring results of smart devices with regular inspection and maintenance. Active maintenance can save a great deal of work, improve the reliability and life of equipment, and supplement with proper regular routine maintenance, which can better ensure that the hydraulic system is in the best working conditions and equipment state.

 

Status monitoring and active maintenance are the future direction of hydraulic equipment maintenance. Key parameters such as particle contamination, water pollution, and temperature of hydraulic oil must be monitored online in real time to prevent accidents and prevent equipment from severely deteriorating. If it is found that the key parameters are abnormal, it is necessary to perform maintenance at any time, and troubleshoot according to the alarm parameters. Before a serious problem occurs, the early-warning phase discovers and solves problems in a timely manner. It is the key to active maintenance and is the highest cost-effective solution. The following figure is Beijing Hangfeng's multi-parameter integrated detection sensor. Regular maintenance is a necessary condition for hydraulic equipment. Check the attachment on the filter screen during the test. If there are too many metal powders, it will mark the wear of the pump or cylinder pulling. In this regard, it is necessary to diagnose and take appropriate measures before starting up. If it is found that the filter is damaged and dirt accumulates, replace it promptly and replace the hydraulic oil if necessary. After 500 hours of construction machinery operation, generally no matter how the condition of the filter element should be replaced, because with the naked eye is difficult to perceive the small damage of the filter element, if a long time high temperature operation should also be properly replaced filter element in advance.

 

After the equipment is used for a long time, the filter should be cleaned, the hydraulic oil tank should be cleaned, the filter element and the hydraulic oil should be replaced, and the long-term high-temperature operation oil change time should be appropriately advanced. If you can guide oil change through oil detection analysis is the most economical, but pay attention to prolong the use of hydraulic oil, should be tested once every 100h, in order to promptly find and replace the deterioration of hydraulic oil.

 

After approaching the life cycle of the original construction machinery, the hydraulic system of the construction machinery is required to be inspected by professionals for necessary adjustment and maintenance. According to practice, imported hydraulic pumps and hydraulic motors must be overhauled after 10,000 hours of operation. Otherwise, hydraulic pumps and hydraulic motors may be damaged due to disrepair, which is a fatal damage to the hydraulic system.

 

3, to prevent solid impurities mixed with the hydraulic system

 

Clean hydraulic oil is the life of the hydraulic system. There are many precision parts in the hydraulic system, some have damping holes or gaps. If the solid impurity invades, it will cause the precision joints to be damaged, card issuing and oil passage blocking, which will endanger the safe operation of the hydraulic system. Common solid material intrusion approaches include: impervious hydraulic oil; impure clean refueling equipment; refueling and careless maintenance; and hydraulic component descaling. Solid impurities can be prevented from invading the system in the following ways:

 

(1) The hydraulic oil must be filtered when refueling, and the refueling tool should be cleaned reliably. It is not possible to remove the filter at the filler port of the hydraulic tank in order to increase the refueling speed. Refuelling personnel should use clean gloves and work clothes.

 

(2) Remove the cover of the hydraulic oil tank, filter cover, detection hole, hydraulic oil pipe, etc. during maintenance, and avoid the dust when the oil passage of the hydraulic system is exposed. The dismantling site must be thoroughly cleaned before opening. When dismantling the hydraulic tank filler cap, first remove the dirt around the fuel tank cap, loosen the fuel tank cap and remove any debris that remains in the joint (do not flush it with water to prevent water from seeping into the tank). Make sure that the cap can only be opened after cleaning. If you need to use the wiping material and hammer, you should choose a wiping material that can not get rid of fiber impurities and a special hammer that hits the surface with rubber. Hydraulic components, hydraulic hoses should be carefully cleaned, and then assembled with high pressure air. Use a genuine, well-packed filter cartridge (if the packaging is damaged, it may be dirty even though the filter cartridge is intact). Clean the filter at the same time when changing the oil, and carefully remove the dirt from the filter housing by applying the wipe material before installing the filter element.

 

(3) The hydraulic oil for the hydraulic system must use the same hydraulic oil as that used in the system. The oil temperature should be between 45~80°C. Use high flow rate to remove impurities from the system as much as possible. The hydraulic system should be cleaned more than three times, and all the oil should be discharged out of the system after each cleaning. After cleaning, clean the filter and replace the new filter with new oil.

 

4, to prevent air and water invasion of the hydraulic system

 

To prevent air from invading the hydraulic system, the hydraulic oil contains air with a volumetric ratio of 6% to 8% at normal atmospheric pressure. When the pressure is reduced, the air is released from the oil, and the air bubbles burst to make the hydraulic element “cavitation” and generate noise. The large amount of air entering the oil will increase the "cavitation" phenomenon, increase the compressibility of the hydraulic oil, make the work unstable, reduce the work efficiency, and cause adverse effects such as "crawling" of the actuator. In addition, the air will also oxidize the hydraulic oil and accelerate its deterioration. Prevent air intrusion should pay attention to the following points:

 

1) After maintenance and oil change, the air in the system shall be excluded according to the provisions of the "operating instructions".

 

2) The suction nozzle of the hydraulic pump must not expose the oil surface. The suction pipeline must be sealed well.

 

3) The seal of the oil pump drive shaft should be good. When replacing the oil seal, a “double-lip” genuine oil seal should be used instead of a “single-lip” oil seal, because the “single-lip” oil seal can only seal oil in one direction and does not have seal gas. The function.