For mechanized construction enterprises, the construction machinery technical status is good or not whether the normal production of enterprises can be a direct factor. In the case of hydraulically driven construction machinery, the normal operation of the hydraulic system is a major hallmark of its good technical condition. The qualified hydraulic oil is the reliable operation of the hydraulic system to ensure that the correct maintenance is the fundamental hydraulic system to run reliably. 1 Select the appropriate hydraulic fluid Hydraulic oil in the hydraulic system plays the role of pressure transmission, lubrication, cooling, sealing, hydraulic oil inappropriate choice is the hydraulic system failure and durability of the early decline. The hydraulic oil should be chosen according to the grade specified in the instruction manual of "random use", and when the special oil needs to be used in special circumstances, its performance should be the same as that of the original grade. Different grades of hydraulic oil can not be mixed to prevent hydraulic oil chemical reaction, performance changes. Dark brown, white, odor of hydraulic oil is a deterioration of oil, you can not use the air filter. 2 to prevent the mixing of solid impurities into the hydraulic system Clean hydraulic oil is the life of the hydraulic system. Hydraulic system has many sophisticated parts, and some damping holes, and some have gaps and so on. If the solid impurities invade will cause precision parts strain, hairpin, oil blockage, endangering the safe operation of the hydraulic system. General solid impurities invade the hydraulic system are: hydraulic oil dirty; refueling tools dirty; fuel and maintenance, carelessness; hydraulic components such as scaling. From the following aspects to prevent solid impurities intrusion system: 2.1 refueling hydraulic oil filter must be filling, refueling tools should be reliable and clean. It is not possible to remove the filter at the fuel filler opening to increase the filling rate. Refueling staff should use clean gloves and work clothes to prevent solid impurities and fiber impurities into the oil. 2.2 Maintenance Disassembly hydraulic tank fuel cap, filter cover, test hole, hydraulic tubing and other parts, resulting in the system oil gallery exposed to avoid dust, demolition site must be thoroughly cleaned before opening. For example, when removing the fuel filler cap, first remove the dirt around the fuel filler cap, loosen the cap, remove the debris remaining at the joint (can not be rinsed with water to prevent the water from penetrating into the fuel tank). If wipe materials and hammers are to be used, the wipe material that does not contain fiber impurities and the special hammer that attaches rubber to the striking surface should be selected. Hydraulic components, hydraulic hose to carefully clean, dry with high pressure air after assembly. Use well-packaged genuine filter (the packaging damage, although the filter is intact, may not clean). Change the oil while cleaning the filter, install the filter before the application of wipe material carefully clean the bottom of the filter shell dirt. 2.3 Cleaning of hydraulic system The cleaning oil must use the same hydraulic oil as used in the system. The oil temperature should be between 45 and 80 ° C. The system should remove impurities from the system as much as possible. Hydraulic system to be repeatedly washed more than three times, each time after cleaning, taking advantage of oil heat all its release system. Cleaning and then cleaning the filter, replace the new filter after filling new oil. 3 to prevent the invasion of air and water hydraulic system 3.1 to prevent air intrusion Hydraulic system at room temperature under normal pressure hydraulic fluid contains 6 to 8% by volume of air, when the pressure decreases when the air will be free from the oil, the bubble rupture of hydraulic components "Cavitation", resulting in noise. A large amount of air into the oil will make the phenomenon of "cavitation" aggravated, hydraulic oil compressibility increases, unstable work, reduce work efficiency, the implementation of components work "crawling" and other adverse consequences. In addition, the air will also make the hydraulic oil oxidation, accelerate the deterioration of oil. To prevent air intrusion should pay attention to the following points: 1, maintenance and oil change according to random "User's Guide" rule out the air in the system, to normal operation. 2, hydraulic pump suction nozzle shall not be exposed oil, suction pipe must be sealed well. 3, pump drive shaft seal should be good, pay attention to replace the seal should be used when the "lips" genuine oil seal, can not be replaced by "single lip" seal, because the "single lip" seal can only be one-way seal oil, do not have Gas seal function. The unit had a Liugong ZL50 loader overhaul, the hydraulic pump continuous "cavitation" noise, the fuel tank automatically raise the fault and so on, after the query hydraulic pump repair process and found that the hydraulic pump drive shaft seal misuse " Single lip "oil seal caused. 3.2 to prevent water intrusion Hydraulic system contains excessive water, hydraulic components will rust, oil emulsion deterioration, lubricating oil film to reduce the intensity and accelerate mechanical wear and tear. In addition to maintenance to prevent moisture invasion, but also pay attention to when the oil tank is not in use, to tighten the lid, it is best placed upside down; water with large oil after repeated filtration, once the filter to be replaced once dried filter paper, In the absence of special equipment testing, the oil can be dropped onto the hot iron plate, no steam emerge and immediately burn before filling. 4 Notes in work 4.1 Mechanical work should be gentle and smooth Mechanical work should be avoided in the rough, otherwise it will inevitably have an impact load, so that mechanical failure frequency, greatly reducing the service life. Impact load generated during operation, on the one hand the early mechanical parts wear, fracture, broken, on the one hand to produce impact pressure in the hydraulic system, the impact pressure will make the hydraulic components damaged, oil seals and high pressure pipe joints and hose nip Premature failure spill or burst pipe, relief valve frequent action oil temperature rise. My unit had a new purchase of a UH171 shovel excavator, the operation every 4 to 6 days will be leaking oil pipe or burst, tubing is a pure imported random products, the test did not quality problems. Through on-site observation, it was found that when the door was opened and closed, strong impact limit block and door frame were caused. To effectively avoid the impact load: must strictly enforce the operating procedures; hydraulic valve open, closed can not be too fast too fast; to avoid the working device components to the extreme position of a strong impact; hydraulic equipment without impact function can not use the working device Excavator bucket) violent impact on the work object in order to achieve the purpose of crushing. There is also a noteworthy problem: the operator must remain stable. Because each device control system has a certain gap between the free gap, the connection part of the degree of wear and tear so the gap is also different, the size of the engine and hydraulic system output also vary, these factors give the device personality. Only the operator using the device to seriously explore and modify their manipulation to adapt to the device's personality, after long-term operation, in order to develop a good operating habits in line with the device's personality. The general machinery industry insisted on determining the system, which is one of the factors. 4.2 pay attention to cavitation and overflow noise operation should always pay attention to the hydraulic pump and the relief valve sound, if the pump "cavitation" noise, after exhaust can not be eliminated, should identify the cause of troubleshooting before use. If an actuator does not work slowly when loaded, and accompanied by relief valve overflow sound, should immediately shut down for maintenance. 4.3 Strict implementation of delivery system Shift drivers parked machinery, to ensure the succession of drivers to check the safety and inspection to the exact level. Whether the system is leaking, the connection is loose, the piston rod and the hydraulic hose are bruised, the hydraulic pump is connected to the low pressure inlet pipe is reliable, the fuel tank is correct, etc., is the successor to the hydraulic system inspection focus. Atmospheric pressure tank also check and clean the vents of the tank to maintain its smooth, in case of blockage caused by the vacuum tank vacuum, resulting in hydraulic oil pump difficult and damaged oil. 4.4 to maintain the appropriate oil temperature Hydraulic system operating temperature is generally controlled between 30 ~ 80 ℃ appropriate (dangerous temperature ≥ 100 ℃). Hydraulic system oil temperature is too high can lead to: the viscosity of the oil is reduced, easily lead to leakage, the efficiency decreased; lubricant film strength is reduced to accelerate the mechanical wear and tear; generate carbides and silt ballast; oil oxidation accelerates deterioration of oil quality; Hose premature aging and so on. In order to avoid over-temperature: Do not overload for a long time; Note radiator fin should not be oil pollution, to prevent dust adhesion affect the cooling effect; To maintain sufficient oil to facilitate circulation of oil cooling; Avoid high-temperature noon time. Oil temperature is too low, the oil viscosity, poor liquidity, resistance, low efficiency; when the oil temperature is below 20 ℃, sharp turn easily damaged hydraulic motors, valves, pipes and so on. At this time need warm-up operation, start the engine, idling idle time 3 ~ 5min, the medium-speed throttle to increase engine speed, control the handle to work any one action device (such as excavator Zhang Dou) to the extreme position, to maintain 3 ~ 5min so that the hydraulic oil through the overflow heating. If the oil temperature is lower you need to increase the warm-up time. 4.5 Hydraulic pressure and fuel tank control Pressure tank in the work should always pay attention to the tank pressure, the pressure must be kept in the random "instructions" within the scope of. Pressure is too low, easy to damage the pump oil shortage, the pressure is too high, will make the hydraulic system oil leakage, easy to cause low-pressure oil pipe burst. After repairing and changing the oil, exhaust the air in the system and check the oil level according to the instructions in the random "Operation Manual", stop the machine in a flat place, check the oil level again after the engine is off for 15 minutes, if necessary Be added. 4.6 Other precautions To prevent flying stones to combat hydraulic cylinders, piston rods, hydraulic tubing and other components. Piston rod if there is a small injury on the point, we must promptly use the oil stone around the edge of the small mill to prevent damage to the piston rod seal, in the case of oil spills can continue to use. Continuous shutdown in more than 24h equipment, before starting, to the hydraulic pump to prevent damage to the pump dry grinding. 5 regular maintenance precautions Some of the current construction machinery hydraulic system is equipped with intelligent device, the device has some warning of hydraulic system potential hazards, but its scope and extent of monitoring has some limitations, so the hydraulic system inspection and maintenance should be intelligent Device monitoring results and regular inspection and maintenance combined. 5.1250h inspection and maintenance Check the filter on the filter attachment, such as excessive metal powder, often marking the pump wear or cylinder pull cylinder, which must be confirmed and take appropriate measures before the boot. If it is found that the filter damage, dirt accumulation, to be promptly replaced, if necessary, while changing oil.