For mechanized construction enterprises, whether the technical condition of construction machinery is good or not is a direct factor for the normal production of enterprises.

As far as hydraulic transmission engineering machinery is concerned, the normal operation of the hydraulic system is a major sign of its good technical condition.

Qualified hydraulic oil is the guarantee of the reliable operation of the hydraulic system, and the correct maintenance is the foundation of the reliable operation of the hydraulic system.

To this end, I according to the work practice, on the general working environment of engineering machinery hydraulic system maintenance for a rough discussion.

1. selection of suitable hydraulic oil

Hydraulic oil plays the role of pressure transmission, lubrication, cooling and sealing in the hydraulic system. Inappropriate selection of hydraulic oil is the main reason for the early failure and durability of the hydraulic system.

The hydraulic oil shall be selected according to the brand specified in the random "Operation Manual". When the substitute oil is required in special circumstances, its performance shall be the same as that of the original brand.

Different grades of hydraulic oil can not be mixed to prevent the hydraulic oil from chemical reaction and performance changes. Dark brown, Milky White, peculiar smell of hydraulic oil is deteriorated oil, can not be used.

2. to 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 with damping holes, some with gaps and so on. Intrusion of solid impurities will cause strain on precision coupling parts, hairpin, blockage of oil passage, etc., endangering the safe operation of the hydraulic system. General solid impurities invade the hydraulic system: hydraulic oil is not clean; refueling tools are not clean; refueling and repair, maintenance careless; hydraulic components desquamation. Solid impurities can be prevented from invading the system in the following aspects:

1When refueling:

The hydraulic oil must be filtered and filled, and the filling tool should be reliably cleaned. Do not remove the filter at the fuel filler port of the fuel tank to increase the refueling speed. Refueling personnel should use clean gloves and work clothes to prevent solid impurities and fiber impurities from falling into the oil.

2During maintenance:

Remove the oil filler cap, filter cap, detection hole, hydraulic oil pipe and other parts of the hydraulic oil tank to avoid dust when the oil passage of the system is exposed. The removed parts must be thoroughly cleaned before opening. For example, when removing the filler cap of the hydraulic oil tank, first remove the soil around the filler cap. After loosening the filler cap, remove the sundries remaining at the joint (do not flush with water to prevent water from penetrating into the oil tank). Only after cleaning can the filler cap be opened.

If you need to use wiping materials and hammers, you should choose wiping materials that do not drop fiber impurities and special hammers with rubber attached to the hitting surface. The hydraulic components and hydraulic hoses shall be carefully cleaned and dried with high-pressure air before assembly. Choose a genuine goods filter element with intact packaging (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, and carefully clean the dirt at the bottom of the filter housing with wiping material before installing the filter element.

3Cleaning of hydraulic system:

The cleaning oil must use the same brand as the hydraulic oil used in the system, and the oil temperature is45~80Between ℃, use large flow to take away the impurity in the system as much as possible. The hydraulic system should be cleaned repeatedly for more than three times. After each cleaning, all of them should be released from the system when the oil is hot. Clean the filter after cleaning, replace the new filter element and add new oil.

3. to prevent air and water intrusion into the hydraulic system

1Prevent air from invading the hydraulic system

At normal pressure and normal temperature, the hydraulic oil contains a volume ratio6~8%When the pressure is reduced, the air will free from the oil, and the bubbles will burst to make the hydraulic components“cavitation”Generating noise. A lot of air into the oil will make“cavitation”The phenomenon is aggravated, the hydraulic oil compressibility increases, the work is unstable, the work efficiency is reduced, and the actuator appears to work.“Crawling”Such as adverse consequences.

In addition, the air will make the hydraulic oil oxidation, accelerate the deterioration of the oil. To prevent air intrusion should pay attention to the following points:

　　（1), after maintenance and oil change, the air in the system must be removed according to the "Instruction Manual" before normal operation.

　　（2), the oil suction pipe mouth of the hydraulic oil pump shall not be exposed to the oil surface, and the oil suction pipe must be well sealed.

　　（3), the oil pump drive shaft seal should be good, pay attention to replace the oil seal should be used“Lips”genuine goods oil seal cannot be used“single lip”oil seal instead, because“single lip”The oil seal can only seal oil in one direction and does not have the function of sealing gas.

There was one.5After the overhaul of the ton loader, the hydraulic oil pump appears continuous“cavitation”Noise, automatic increase of oil level in the oil tank and other faults. 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”Due to the oil seal.

2Prevent water intrusion into hydraulic system

Oil contains excessive moisture, will make the hydraulic components rust, oil emulsification deterioration, lubricating oil film strength decreased, accelerate mechanical wear. In addition to preventing water intrusion during maintenance, attention should also be paid to tightening the lid when the oil storage barrel is not in use, preferably upside down. Oil with high water content should be filtered many times, and the dried filter paper should be replaced every time it is filtered. When there is no special instrument for detection, the oil can be dropped onto the hot iron plate, and no steam can be emitted and burned immediately before filling.

Matters needing attention in 4. operation

1Mechanical operation shall be gentle and smooth

Mechanical operation should avoid rough, otherwise it will inevitably produce impact load, so that frequent mechanical failure, greatly shorten the service life.

The impact load generated during operation, on the one hand, causes early wear, fracture, and crushing of mechanical structural parts, on the other hand, it causes impact pressure in the hydraulic system, and the impact pressure will cause damage to hydraulic components, oil seals and high-pressure tubing joints and rubber hoses. Premature failure of oil leakage or pipe burst, and frequent action of overflow valves. The oil temperature rises.

Have purchased a new excavator, operation every4~6Tiandoumen oil pipe will leak or burst. The oil pipe is randomly imported pure genuine goods and has no quality problem after testing. Through on-site observation, it is found that the bucket door is caused by strong impact on the limit block and door frame when opening and closing. To effectively avoid the impact load: must strictly implement the operating procedures; hydraulic valve opening and closing can not be too fierce too fast; to avoid the working device components move to the limit position to produce strong impact; no impact function of hydraulic equipment can not use the working device (such as excavator bucket) violent impact of the operation object to achieve the purpose of crushing.

There is another problem worth noting: the operator should remain stable. Because the free clearance of each equipment control system has a certain difference, the degree of wear of the connection parts is different, so the clearance is also different, and the output of the engine and hydraulic system is also different. These factors give the equipment its personality.

Only the operator who uses the equipment carefully groping and revising his own manipulation to adapt to the personality of the equipment can develop good operating habits that conform to the personality of the equipment after long-term operation. The general machinery industry adheres to the fixed person-to-machine system, which is also one of the factors.

2Pay attention to cavitation and overflow noise

Operation should always pay attention to the sound of the hydraulic pump and relief valve, if the hydraulic pump appears“cavitation”Noise, after the exhaust can not be eliminated, should find out the cause of troubleshooting before use. If an actuator moves slowly when there is no load and is accompanied by overflow sound of overflow valve, it should be shut down for maintenance immediately.

3Strictly implement the delivery*Violation of words*System

When the shift driver parks the machinery, ensure that*Violation of words*The driver checks for safety and checks to the exact oil level. Whether the system leaks, whether the connection is loose, whether the piston rod and hydraulic hose are damaged, whether the low-pressure oil inlet pipe of the hydraulic pump is connected reliably, whether the oil level of the oil tank is correct, etc., yes*Violation of words*The focus of the driver's inspection of the hydraulic system. The normal pressure oil tank should also check and clean the air hole of the oil tank to keep it unblocked, so as to prevent the air hole from blocking the vacuum of the oil tank, which makes it difficult for the hydraulic oil pump to suck oil and cause damage.

4Maintain proper oil temperature

The working temperature of the hydraulic system is generally controlled30~80between ℃ is appropriate (dangerous temperature≥100C). Excessive oil temperature of the hydraulic system will lead to: reduced oil viscosity, easy to cause leakage, and reduced efficiency; reduced lubricating oil film strength, accelerated mechanical wear; formation of carbides and sludge; oil oxidation accelerates oil quality deterioration; oil seals, high pressure The hose is prematurely aging, etc.

In order to avoid excessive temperature: do not overload for a long time; pay attention to the radiator fins not to be polluted by oil to prevent dust from affecting the heat dissipation effect; maintain enough oil to facilitate the circulation of oil; do not work all day in hot summer, and avoid high temperature at noon.

When the oil temperature is too low, the oil viscosity is high, the fluidity is poor, the resistance is large, and the work efficiency is low; when the oil temperature is lower20℃, sharp turn easy to damage the hydraulic motor, valve, pipeline, etc. At this time, it is necessary to warm up the engine, start the engine, and run at idle speed with no load.3~5minAfter that, increase the engine speed with the medium speed throttle, and control the handle to make any action of the working device (such as the excavator bucket) to the limit position, and keep it3~5minMake the hydraulic oil warm up through the overflow. If the oil temperature is lower, it is necessary to increase the warm-up operation time appropriately.

5Control of air pressure and oil quantity in hydraulic oil tank

The pressure type fuel tank should pay attention to the air pressure of the fuel tank at any time during work, and its pressure must be kept within the range specified in the "Instruction Manual.

If the pressure is too low, the oil pump is easily damaged due to insufficient oil suction. If the pressure is too high, the hydraulic system will leak oil and easily cause the low-pressure oil circuit to burst. For the equipment after maintenance and oil change, after the air in the system is exhausted, check the oil level status according to the "Instruction Manual", park the machine in a flat place, and the engine stops.15minThen recheck the oil level and supplement it if necessary.

6Other precautions

During the operation, it is necessary to prevent flying stones from hitting the hydraulic cylinder, piston rod, hydraulic oil pipe and other components. If there is a small point on the piston rod, it is necessary to use an oil stone to grind the edge around the small point in time to prevent damage to the sealing device of the piston rod. It can continue to be used without oil leakage. Continuous shutdown in24hThe above equipment, before starting, to the hydraulic pump oil injection, to prevent the hydraulic pump dry grinding and damage.

5. regular maintenance precautions

1,250hInspection and maintenance

Check the attachment on the filter screen, such as excessive metal powder, often marks the oil pump wear or cylinder pull cylinder, which must be diagnosed and take appropriate measures to boot. If the filter screen is damaged and dirt accumulates, replace it in time and change the oil when necessary.

2.500hInspection and maintenance

Regardless of the condition of the filter element, it should be replaced, because it is difficult to detect the small damage of the filter element by naked eyes. If the filter element is operated at high temperature for a long time, it should be replaced in advance.

3,1000hInspection and maintenance

Clean the filter, replace the filter element, clean the hydraulic oil tank, and replace the hydraulic oil. Long-term high temperature operation oil change time should be appropriate in advance. Of course, if the oil quality detection and analysis can be used to guide the oil change is the most economical, but pay attention to the extension of the use of oil, every100hShould be detected once, in order to find and replace the deterioration of oil in time.

4,7000hand10000hInspection and maintenance

The hydraulic system shall be inspected by professional personnel, and necessary adjustment and maintenance shall be carried out. According to practice, imported hydraulic pumps and hydraulic motors work10000hIt must be overhauled, otherwise the hydraulic pump and motor may be damaged due to disrepair, which will cause fatal damage to the hydraulic system.