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What are the construction machinery? They all contain 啥, many people may not know or understand, then let us introduce: 1 dig machinery such as single bucket digger (also can be divided into crawler digger and tire digger), Multi-dump excavator (also divided into bucket-type excavator and chain bucket excavator), multi-dump trencher (also can be divided into bucket digging machine and chain bucket digging machine), tumbling excavator, Milling and excavation machines, tunnel boring machines (including shield ditch machinery). 2 shoveling transport machinery such as bulldozers (can be divided into tire-type bulldozers and crawler-type bulldozers), scrapers (also can be divided into crawler self-propelled scrapers, tire self-propelled scrapers and towed scrapers), Loaders (can be divided into tire loaders and crawler loaders, graders (also can be divided into self-propelled graders and tow graders), transport vehicles (also can be divided into single-axis transport vehicles and dual-axle traction Transport vehicles), flatbed trucks, dump trucks, etc. 3 Hoisting machinery such as tower cranes, self-propelled cranes, mast cranes, grab cranes, etc. 4 compaction machinery such as tire roller, smooth roller, single-foot roller, Vibratory roller, tamping machine, tamping machine, etc. 5 pile machinery such as drilling machine, diesel pile driver, vibration pile driver, pile driver, etc. 6 reinforced concrete machinery such as concrete mixer, concrete mixing station, concrete mixing plant, concrete Conveying pump, concrete mixer truck, concrete jet machine, concrete vibrator, steel bar processing machinery, etc. 7 Pavement machinery such as flat machine, ballast cleaning machine, etc. 8 Rock drill Such as rock drilling rigs, pneumatic rock drills, electric rock drills, internal combustion rock drills and downhole rock drills, etc. 9 Other construction machinery, such as bridge erecting machines, pneumatic tools (aerodynamic tools), etc. The boom automatically falls, is a tire loader The shortcomings often encountered in the use process. The loader often works under the condition that the boom automatically falls, not only makes the loader's working power low, the hydraulic oil temperature rises too high, the service life decreases, and it will also constitute the loader initiator. The fuel consumption increased. The Shaanxi loader sold clarified the reason for the automatic falling of the boom: Under normal circumstances, when the boom cylinder piston rod reaches the limit orientation, the boom cylinder no longer acts, the hydraulic oil is tightened, and the hydraulic system pressure continues to rise. When the hydraulic system pressure reaches the loader working device pressure setting value (ie, the main safety valve calibration value), the main safety valve is opened, and the high pressure oil output from the gear pump will be released from the main safety valve to the hydraulic oil tank.
According to the above principle, the reasons for the automatic fall of the boom are as follows:
(1) Hydraulic hose leakage Assume that the hydraulic pipe joint seal ring is damaged, the crimping is not real, or the pipe body is damaged. The hydraulic oil in the high pressure cavity of the boom cylinder will spray hydraulic oil from the broken and gap, thus causing the boom Automatically falling.
(2) Boom control valve spool defect The boom reversing valve spool can not return to the neutral position, the valve core is seriously worn and the seal is not tight, and the hydraulic oil in the high pressure chamber of the boom cylinder will flow back to the hydraulic tank, resulting in The boom automatically falls.
(3) Disadvantages of main safety valve When the main pressure of the hydraulic system exceeds the set value, the hydraulic oil in the main oil supply line of the hydraulic system will be relieved by the main safety valve. Assuming that the main safety valve is stuck or damaged, it will constitute an abnormal pressure relief of the hydraulic system and then cause the boom to fall automatically.
(4) Disadvantages of the boom of the boom cylinder During the rapid movement of the piston rod of the boom cylinder, the air in the boom cylinder will be attacked by the sudden tightening, and the high temperature and high pressure will occur. If the high temperature and high pressure of the attack exceed the tolerance limit of the boom cylinder seal, the seal will be invalid. After the boom cylinder piston seal fails, the hydraulic oil in the rodless chamber will leak to the rod cavity, and then the boom will automatically fall.

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