For machinery construction enterprises, the good condition of construction machinery technology is a direct factor for the normal production of enterprises. Most construction machinery now uses electromechanical-hydraulic integration, and the normal operation of the hydraulic system is a major sign of its good technical condition. Qualified hydraulic oil is the guarantee for reliable operation of the hydraulic system. Correct maintenance is fundamental to the reliable operation of hydraulic systems. The editor specially summarized some precautions for hydraulic system maintenance.
The hydraulic system can only be used by giants of used construction machinery if they are well maintained.
Hydraulic transmission technology almost penetrates into all modern engineering fields. Compared with mechanical transmission and electric transmission, hydraulic transmission has unique advantages:
(1) Under the same volume, the hydraulic transmission device generates more power than the electrical device: (2) Under the same power, the hydraulic transmission device is small, light, and compact; (3) The hydraulic transmission quality is stable 3. High mechanical efficiency and good low-speed load characteristics.
Due to the friction loss and leakage loss, the energy loss of the hydraulic transmission system is large; the cleanliness of the oil is required to be high and requires regular replacement; the change in oil temperature will affect the control of the running speed and the shortcomings of noise. In addition, most construction machinery works outdoors, often in the dirt, dust, wind, frost, snow and rain. The working load is often variable and accompanied by vibration, and the working speed is often in a transient transition with inertial impact. Therefore, there should be special requirements for the hydraulic system of construction machinery: it should have good environmental adaptability and reliable sealing; it should have higher working reliability and sensitive real-time strain capability; it should have better maneuverability to make the system Closed and able to make various changes. Because of this, when we use the hydraulic system, we should operate in accordance with the relevant regulations.
1. Choose the right hydraulic oil
Hydraulic oil plays the role of transmitting pressure, lubricating, cooling and sealing in the hydraulic oil system. Improper selection of hydraulic oil is the main reason for the early failure and decline of durability of the hydraulic system. The hydraulic oil should be selected according to the grade specified in the random "Instruction Manual". In special cases, when alternative oil is required, the performance should be the same as that of the original grade. The hydraulic oils of different brands can not be mixed to prevent the hydraulic oil from chemical reactions and performance changes. Dark brown, milky white, smelly hydraulic oil is metamorphic oil and cannot be used.
2. Precautions for regular maintenance
At present, some engineering machinery hydraulic systems are equipped with intelligent devices. This device has certain warning functions for the hydraulic system, but its monitoring range and accuracy have certain limitations. Therefore, the inspection and maintenance of the hydraulic system should be based on the results of the intelligent device monitoring. Regular inspection and maintenance are combined.
250h inspection and maintenance
Check the filter screen for attachments, such as excessive metal powder, often indicating wear on the oil pump or cylinder pulling. In this regard, you must confirm the diagnosis and take corresponding measures before you can switch on. If it is found that the filter is damaged and dirt accumulates, it should be replaced in time, and if necessary, the hydraulic oil should be replaced at the same time.
500h inspection and maintenance
After 500 hours of construction machinery operation, the filter element should be replaced regardless of the condition of the filter element, because it is difficult to detect the small damage of the filter element with the naked eye, and the filter element should be replaced in advance if it is operated for a long time at high temperature.
1000h inspection and maintenance
At this time, the filter should be cleaned, the hydraulic oil tank should be cleaned, the filter element and hydraulic oil should be replaced, and the oil change time should be properly advanced for long-term high temperature operation. It is the most economical to guide the oil change through oil quality inspection and analysis, but pay attention to the extended use of hydraulic oil. It should be tested every 100 hours in order to find and replace the deteriorated hydraulic oil in time.
7000h and 10000h inspection and maintenance
The hydraulic system of construction machinery at this time needs to be inspected by professionals to make necessary adjustments and maintenance. According to practice, imported hydraulic pumps and hydraulic motors must be overhauled after working for 10000h, otherwise the hydraulic pumps and hydraulic motors 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 hydraulic system. There are many precision couples in the hydraulic system, and some are equipped with damping holes or gaps. Intrusion of solid impurities will cause strain on precision parts, card issuance, blockage of oil passages, etc., endangering the safe operation of the hydraulic system. The general solid material intrusion routes are: unclean hydraulic oil; unclean refueling tools; careless refueling, repair and maintenance; descaling of hydraulic components, etc. It can prevent solid impurities from invading the system from the following aspects:
(1) When refueling, the hydraulic oil must be filtered, and the refueling tools should be clean and reliable. The filter at the filling port of the hydraulic oil tank cannot be removed in order to increase the filling speed. Refuelers should use clean gloves and work clothes.
(2) Remove the fuel filler cap, filter cover, detection hole, hydraulic oil pipe and other parts of the hydraulic tank during maintenance. Avoid dust when the hydraulic system oil channel is exposed. The dismantled parts must be thoroughly cleaned before opening. If removing the fuel cap of the hydraulic tank, first remove the mud around the tank cap, unscrew the tank cap and remove it
Debris left in the joints (do not rinse with water to prevent water from seeping into the fuel tank). Open the fuel tank cover only after cleaning. If you need to use the test material and hammer, you should choose the wiping material that does not remove fiber impurities and the special hammer with rubber attached to the hitting surface. Hydraulic components and hydraulic hoses should be carefully cleaned and assembled after being dried with high-pressure air. Use a genuine filter element in a well-packed state (if the package is damaged, the filter element may be unclean if it is intact). Clean the filter at the same time when changing the oil. Before installing the filter element, wipe the material carefully to remove the dirt inside the filter housing.
(3) The cleaning oil of the hydraulic system must use the same type of hydraulic oil used in the system. The oil temperature is between 45 and 80 ℃, and the impurities in the system should be taken away with a large flow rate. The hydraulic system should be cleaned repeatedly more than three times, and after the cleaning is completed, release all of the oil while the oil is hot. After cleaning, clean the filter, replace with a new filter and add new oil.
4. Prevent air and water from invading the hydraulic system
Prevent air from intruding into the hydraulic system. At normal pressure and temperature, the hydraulic oil contains air with a volume ratio of 6% to 8%. When the pressure is reduced, the air will be freed from the oil. The air bubbles will rupture and cause "cavitation" of the hydraulic components, causing noise. A large amount of air entering the oil will aggravate the "cavitation" phenomenon, increase the compressibility of the hydraulic oil, make the work unstable, reduce the working efficiency, and cause "bad crawling" of the actuator. In addition, the air will oxidize the hydraulic oil and accelerate its deterioration. Pay attention to the following points to prevent air intrusion:
1) After maintenance and oil change, the air in the system should be excluded according to the provisions in the random "Operating Instructions".
2) The oil suction pipe port 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 good. When replacing the oil seal at this place, the "double lip" genuine oil seal should not be used instead of the "single lip" oil seal, because the "single lip" oil seal can only seal the oil in one direction, without the sealing Function. After overhauling a Liugong ZL50 loader in this unit, the hydraulic oil pump appeared
Continued "cavitation" noise, oil tank oil level automatically increased and other faults, after querying the hydraulic oil pump repair process, it was found that the oil seal of the hydraulic oil pump drive shaft was misused by the "single lip" oil seal.
