Precautions for maintenance of the hottest hydraul

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Precautions for hydraulic part maintenance

for mechanical construction enterprises, the good technical condition of construction machinery is a direct factor for the normal production of enterprises. Nowadays, most construction machinery adopts electromechanical hydraulic integration, and the normal operation of the hydraulic system is a major sign of its good technical status. Qualified hydraulic oil is the guarantee of reliable operation of hydraulic system. Correct maintenance is the foundation of reliable operation of hydraulic system. Therefore, according to the working practice, the author makes a rough discussion on the maintenance of the hydraulic system of construction machinery

1 select the appropriate hydraulic oil

hydraulic oil plays the role of pressure transmission, lubrication, cooling and sealing in the hydraulic oil system. Improper selection of hydraulic oil is the early failure and durability decline of the hydraulic system. 8 Batch experiment: the main reason for samples with the same parameters. The hydraulic oil shall be selected according to the brand specified in the accompanying "operation manual". When it is necessary to use alternative oil under special circumstances, its performance shall be the same as that of the original brand. Hydraulic oil of different brands cannot be mixed to prevent chemical reaction and performance change of hydraulic oil. The dark brown, milky white and smelly hydraulic oil is deteriorated oil and cannot be used

2 precautions for regular maintenance

at present, some hydraulic systems of construction machinery are equipped with intelligent devices, which have warning functions for some hidden dangers of the hydraulic system, but their monitoring scope and accuracy have certain limitations, so the inspection and maintenance of the hydraulic system should combine the monitoring results of intelligent devices with regular inspection and maintenance

2.1 250h inspection and maintenance

check the attachments on the filter. If there is too much metal powder, it often indicates that the oil pump is worn or the oil cylinder is pulled. For this, it must be confirmed and corresponding measures must be taken before starting the machine. In case of filter damage and dirt accumulation, replace it in time, and replace the hydraulic oil at the same time if necessary

2.2 500h inspection and maintenance

after 500h operation of construction machinery, the filter element should be replaced regardless of its condition, because it is difficult to detect the small damage of the filter element with the naked eye. If it is operated at high temperature for a long time, the filter element should also be replaced appropriately in advance

2.3 1000h inspection and maintenance

at this time, the filter and hydraulic oil should be cleaned. The capital is the blood vessel of the enterprise, and the filter element and hydraulic oil should be replaced. For long-term high-temperature operation, the oil change time should be appropriately advanced. Hold the operator to stop the pendulum for one time (without placing the sample). It is the most economical to guide the oil change through oil quality detection and analysis, but pay attention to the hydraulic oil used for extension. The steel wire and strand for prestressed concrete should be tested every 1038 hours, so as to find and replace the deteriorated hydraulic oil in time

2.4 7000h and 10000h inspection and maintenance

at this time, the hydraulic system of construction machinery needs to be tested by professionals for necessary adjustment and maintenance. According to practice, the imported hydraulic pump and hydraulic motor must be overhauled after working for 10000h, otherwise the hydraulic pump and hydraulic motor may be damaged due to disrepair, which is fatal to the hydraulic system

3 prevent solid impurities from mixing into the hydraulic system

clean hydraulic oil is the life of the hydraulic system. There are many precision coupling parts in the hydraulic system, some of which are equipped with damping holes or gaps. If solid impurities invade, the precision coupling will be strained, stuck, and the oil passage will be blocked, endangering the safe operation of the hydraulic system. The general ways of invasion of solid substances are: dirty hydraulic oil; The refueling tools are dirty; Careless refueling, repair and maintenance; Desquamation of hydraulic components, etc. Solid impurities can be prevented from invading the system from the following aspects:

(1) hydraulic oil must be filtered during refueling, and refueling tools should be reliably cleaned. Do not remove the filter at the oil filler of the hydraulic oil tank in order to improve the oil filling speed. Refueling personnel should use clean gloves and work clothes

(2) during maintenance, remove the oil filler cap, filter cap, inspection hole, hydraulic oil pipe and other parts of the hydraulic oil tank. When the oil duct of the hydraulic system is exposed, avoid dust. The disassembled parts must be thoroughly cleaned before opening. For example, when removing the oil filler cap of the hydraulic oil tank, first remove the soil around the oil tank cap, unscrew the oil tank cap, and then remove the sundries left at the joint (do not flush with water to prevent water from penetrating into the oil tank), and open the oil tank cap only after confirmation of cleaning. If you need to use wiping materials and hammers, you should choose wiping materials that cannot remove fiber impurities and special hammers with rubber attached to the striking surface. Hydraulic components and hydraulic hoses shall be carefully cleaned and assembled after drying with high-pressure air. Select genuine filter element with intact package (if the package is damaged, although the filter element is intact, it may also be dirty). Clean the filter at the same time when changing the oil, and carefully remove the dirt inside the filter housing with wiping materials before installing the filter element

(3) the cleaning oil of the hydraulic system must use the hydraulic oil with the same brand as that used in the system. The oil temperature is between 45~80 ℃, and the impurities in the system should be taken away as much as possible with a large flow. The hydraulic system shall be cleaned repeatedly for more than three times. After each cleaning, it shall be completely discharged from the system when the oil is hot. Clean the filter after cleaning, and add new oil after replacing the filter element

4 prevent air and water from invading the hydraulic system

4.1 prevent air from invading the hydraulic system

under normal pressure and normal temperature, the hydraulic oil contains air with a volume ratio of 6%~8%. When the pressure decreases, the air will be separated from the oil, and the bubble will burst, causing "cavitation" of the hydraulic components and generating noise. A large amount of air entering the oil will aggravate the "cavitation" phenomenon, increase the compressibility of hydraulic oil, work instability, reduce work efficiency, and the actuator will "crawl" and other adverse consequences. In addition, air will oxidize the hydraulic oil and accelerate its deterioration. To prevent air intrusion, the following points should be paid attention to:

1) after maintenance and oil change, the air in the system should be removed according to the provisions of the accompanying operation manual

2) the oil suction pipe orifice of the hydraulic oil pump must not expose the oil surface, and the oil suction pipe must be well sealed

3) the seal of the oil pump drive shaft should be good. When replacing the oil seal at this place, the "double lip" genuine oil seal should be used instead of the "single lip" oil seal, because the "single lip" oil seal can only seal oil in one direction and does not have the function of sealing air. After the overhaul of a Liugong ZL50 loader, the hydraulic oil pump had continuous "cavitation" noise and the oil level in the oil tank increased automatically. After inquiring the repair process of the hydraulic oil pump, it was found that it was due to the misuse of the "single lip" oil seal in the oil seal of the hydraulic oil pump drive shaft

4.2 prevent water from invading the hydraulic system

excessive water in the hydraulic oil will rust the hydraulic components, emulsify and deteriorate the oil, reduce the strength of the lubricating oil film, and accelerate mechanical wear. In addition to preventing moisture intrusion during maintenance, pay attention to tighten the cover of the oil storage barrel when it is not in use, and it is best to place it upside down; Hydraulic oil with high water content shall be filtered for many times, and the dried filter paper shall be replaced every time. When there is no special instrument to detect, the hydraulic oil can be dropped on the hot iron plate, and the filling can be carried out only when there is no steam emerging and burning immediately

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