For engineering construction companies, the quality of construction machinery is the most important factor for companies to ensure that the quality of the project is delivered on time. In terms of hydraulically driven large construction machinery, the normal operation of the hydraulic system is an important sign of its good technical condition. Qualified hydraulic oil is the guarantee for the reliable operation of the hydraulic system, and correct maintenance is the basis for the reliable operation of the hydraulic system. Therefore, we will discuss with you how to maintain and maintain the hydraulic system of the bulldozer based on the experience summarized in the construction for many years.

　　1: Correct selection of hydraulic oil

　　Hydraulic oil plays the role of transmitting pressure, lubricating, cooling and sealing in the hydraulic system. Improper selection of hydraulic oil is the main reason for the early failure and durability of the hydraulic system. The hydraulic oil should be selected according to the label specified in the "User's Manual" of the machine. In special cases, when alternative oil is required, the performance should be the same as the original label. It is recommended not to mix hydraulic oils with different labels to prevent the hydraulic oil from chemical reactions and performance changes. Dark brown, milky white, smelly hydraulic oil is metamorphic oil and should never be used.

　　 2: Prevent 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, some have small damping holes, and some have gaps. If there is foreign matter intrusion, it will cause strain on the precision parts, blockage of the oil passage, etc., endangering the safe operation of the hydraulic system. There are several ways for general impurities to invade the hydraulic system: unclean hydraulic oil; unclean refueling tools; careless refueling, repair and maintenance; hydraulic components, etc. The solid impurities can be prevented from invading the system from the following aspects:

　　When refueling: The hydraulic oil must be filtered and refilled, and the refueling tools should be clean and reliable. The filter at the fuel filler opening of the fuel tank cannot be removed in order to increase the fuel filling speed. Oilers should use clean gloves and work clothes to prevent solid impurities and fiber impurities from falling into the oil.

　　During maintenance: remove the hydraulic oil tank filler cap, filter cover, detection hole, hydraulic oil pipe and other parts, causing the system oil channel to be exposed to avoid dusty places. The disassembly parts must be thoroughly cleaned before they can be opened. For example, when removing the fuel cap of the hydraulic tank, first remove the mud around the tank cap, unscrew the tank cap, and remove the debris remaining at the joints (do not rinse with water to prevent water from seeping into the tank), and open the tank cap only after cleaning. If you need to use the wiping 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 package (the inner packaging is damaged, although the filter element is intact or it may be unclean). Clean the filter at the same time when changing the oil. Before installing the filter element, use the wiping material to carefully clean the bottom dirt in the filter housing.

　　 3: How to clean the hydraulic system

　　 The cleaning oil must use the same hydraulic oil as that used in the system. The oil temperature is between 45 and 80°C, and the impurities in the system should be taken away with a large flow rate as much as possible. The hydraulic system should be cleaned repeatedly more than three times. After each cleaning, 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

　　Under normal pressure and normal temperature, hydraulic oil contains 6-8% of air by volume. When the pressure is reduced, the air will be released from the oil, and the air bubbles will rupture, causing the hydraulic components to "cavitation" and generate noise. A large amount of air entering the oil will aggravate the "cavitation" phenomenon, increase the compressibility of the hydraulic oil, work instability, reduce work efficiency, and the actuator "crawling" and other adverse consequences. In addition, the air will oxidize the hydraulic oil and accelerate the deterioration of the oil. Pay attention to the following points to prevent air intrusion:

　　After maintenance and oil change, the air in the system must be exhausted in accordance with the provisions of this machine's "Instruction Manual" to operate normally.

　　 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. It should be noted that when replacing the oil seal at this place, the "double lip" genuine oil seal should be used, and the "single lip" oil seal can not be replaced, because the "single lip" oil seal can only seal the oil in one direction, and does not have the function of sealing the gas. After a major repair of a Liugong ZL50 loader in this unit, the hydraulic oil pump experienced continuous "cavitation" noise, oil tank oil level automatically increased and other failures. After querying the repair process of the hydraulic oil pump, it was found that the oil seal of the hydraulic oil pump drive shaft was misused. Due to the "single lip" oil seal.

　　Prevent water intrusion into hydraulic system

　　Oil contains excessive moisture, which will cause the corrosion of hydraulic components, emulsification and deterioration of the oil, the strength of the lubricating oil film will be reduced, and mechanical wear will be accelerated.

In addition to preventing water intrusion during maintenance, it is also necessary to tighten the lid when the oil storage barrel is not in use. It is best to place it upside down; oil with a large water content must be filtered many times, and the dried filter paper must be replaced every time the filter is filtered. When there is no special instrument for testing, the oil can be dripped onto the hot iron plate, and no steam will emerge and burn immediately before filling.

　　 5: Dozer construction should be soft and smooth

　　 Bulldozer construction should avoid rough, otherwise it will produce impact load, frequent mechanical failures, greatly shorten the service life. The impact load generated during construction, on the one hand, causes the mechanical structural parts to wear, break, and break early, on the one hand, it generates impact pressure in the hydraulic system, and the impact pressure will damage the hydraulic components, the oil seal, and the junction of the high-pressure oil pipe joint and the hose Premature failure of oil leakage or burst pipe, overflow valve frequent operation, oil temperature rise.

　　 In addition: the operator should develop good driving habits, each driving action should be as smooth and smooth as possible, because the free clearance of the control system of each device is different, and the degree of wear of the connecting parts is different, so the gap is also different.