For mechanized construction companies, the technical status of construction machinery is a direct factor in whether the company can produce normally. As for hydraulically driven construction machinery, the normal operation of the hydraulic system is a major indicator of its good technical status. Qualified hydraulic oil is the guarantee for the reliable operation of the hydraulic system. Correct maintenance is the basis for the reliable operation of the hydraulic system. For this reason, based on our many years of production experience, we will discuss how to maintain the hydraulic system.
1 Select the appropriate hydraulic oil
Hydraulic oil plays the role of transmitting pressure, lubrication, cooling, and sealing in the hydraulic system. Improper selection of hydraulic oil is the main cause of early failure and reduced durability of the hydraulic system. Hydraulic oil should be selected according to the brand specified in the equipment (instructions for use). When a substitute oil is needed in special circumstances, its performance should be the same as that of the original brand. Hydraulic oil of different brands cannot be mixed to prevent chemical reactions in the hydraulic oil. Performance changes: Hydraulic oil that is dark brown, milky white, and has a peculiar smell is deteriorated oil and cannot be used.
2. Prevent solid impurities from mixing into the hydraulic system (the cleaning and dust-free step in this point of production is very important)
Clean hydraulic oil is the life of the hydraulic system. There are many precision coupling parts in the hydraulic system, some have small damping holes, some have gaps, etc. If solid impurities invade, it will cause strain on precision parts, hairpins, blockage of oil passages, etc., endangering the safe operation of the hydraulic system. Generally, the ways for solid impurities to invade the hydraulic system include: unclean hydraulic oil; unclean refueling tools; careless refueling and repair and maintenance; desquamation of hydraulic components, etc. Solid impurities can be prevented from entering the system from the following aspects:
2.1: When refueling
Hydraulic oil must be filtered and refilled, and refueling tools should be reliable and clean. Do not remove the filter at the refueling port of the mailbox in order to provide refueling speed. Refueling personnel should use clean gloves and overalls to prevent solid impurities and fibers from entering the oil.
2.2: During maintenance
When disassembling the hydraulic oil tank filling cap, filter cover, detection hole, hydraulic oil pipe and other parts, avoid dust when the system oil passage is exposed. The disassembled parts must be thoroughly cleaned before opening. For example, when disassembling the refill cap of the hydraulic oil tank, first remove the soil around the fuel tank cap, loosen the oil cap, and remove any debris remaining at the joint (do not flush with water to avoid water seeping into the tank). Open the fuel tank cap only after confirming that it is clean. When you need to use wiping materials and hammers, you should choose wiping materials that do not remove fiber impurities and special hammers with rubber attached to the striking surface. Hydraulic elements and hydraulic hoses must be carefully cleaned, blown with high-pressure air before assembly, and packaged A genuine and intact filter element (the inner packaging is damaged, although the filter element is intact, it may be unclean). Clean the filter at the same time when changing the oil. Before installing the filter element, use wiping materials to carefully clean the dirt at the bottom of the filter housing.
2.3: Cleaning of hydraulic system
The cleaning oil must use the same brand of hydraulic oil as that used in the system. The oil temperature should be between 45 and 80°C. Use a large flow rate to take away impurities in the system as much as possible. The hydraulic system should be cleaned repeatedly for more than three times. After each cleaning, all the oil should be released from the system while it is hot. After cleaning, clean the filter, replace it with a new filter element and add new oil.
3. Prevent air and water from intruding into the hydraulic system
3.1: Prevent air from intruding into the hydraulic system
Hydraulic oil contains air with a volume ratio of 6 to 8% under normal pressure and temperature. When the pressure decreases, the air will be freed from the oil. The bursting of bubbles will cause "cavitation" of hydraulic components and produce noise. A large amount of air entering the oil will aggravate the "cavitation" phenomenon, increase the compressibility of the hydraulic oil, make the operation unstable, reduce the work efficiency, and cause the actuator to "crawl" and other adverse consequences. In addition, air will oxidize the hydraulic oil and accelerate the deterioration of the oil. To prevent air intrusion, the following points should be noted:
1. After maintenance and oil change, the air in the system must be eliminated according to the provisions of the random "Instruction Manual" to ensure normal operation.
2. The oil suction pipe opening of the hydraulic oil pump must not be exposed to the oil surface, and the oil suction pipe must be well sealed.
3. The seal of the oil pump drive shaft should be in good condition. When replacing the oil seal here, you should use a genuine "double-lip" oil seal and cannot replace it with a "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 in our unit, the hydraulic oil pump experienced continuous "cavitation" noise and the oil level in the oil tank automatically increased. After inquiring about the repair process of the hydraulic oil pump, it was found that the oil seal of the hydraulic oil pump drive shaft was misused." Single lip "oil seal".
3.2 Prevent water from intruding into the hydraulic system
Excessive moisture in the oil will cause corrosion of hydraulic components, emulsification and deterioration of the oil, reduce the strength of the lubricating oil film, and accelerate mechanical wear.
In addition to preventing moisture intrusion during maintenance, it is also important to tighten the lid of the oil storage barrel when it is not in use, and it is best to place it upside down; oil with a large water content must be filtered multiple times, and the drying filter paper must be replaced after each filtration. When there is no special instrument for testing, the oil can be dropped on the hot iron plate. Only when no steam comes out and burns immediately can it be refilled.
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