Technical analysis of the sliding bearing of the h

2022-09-19
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Technical analysis of engine sliding bearing (III)

3. Damage to the shaft and bearing bush caused by non moving foreign matters:

there are large foreign matters sandwiched between the bearing bush and the inner wall of the Bush mounting hole, and the moving surface of the bearing bush will produce bumps. When the shaft is running, abnormal wear will start from the bumps and expand to the periphery, causing early damage to the shaft and bearing bush; If there is a large foreign matter between the moving surface of the bearing bush and the shaft, it will be embedded in the alloy layer of the bearing bush after installation. During operation, it will damage the shaft and the bearing bush at the same time; Only after that can the shaft and bearing be tested, and if there are bumps and bumps in the installation holes and other related parts, the shaft and bearing will be damaged or damaged

causes and prevention: the shaft, bearing bush and bearing bush hole (body and connecting rod) are rusted, resulting in oxide or sediment. Before installation, it is necessary to carefully check and clean, especially the inner cavity of oil duct and oil pipe; The installation site must be far away from the site with dust and debris splashing; The tools used for installation shall be clean, and necessary protective measures shall be taken to avoid re pollution. At the same time, the lubricating oil used in assembly shall be clean to prevent dust from mixing; The storage and installation of the shaft, bearing bush and bearing bush hole shall ensure that it does not have enough contact with any metal object with a common stretching stroke of 100 ⑵ 00mm and no collision operation

II. Damage and damage of shaft and bearing bush caused by lubrication system:

1. Damage and damage caused by poor lubrication effect:

when the lubrication effect of shaft and bearing bush fails to meet the requirements, a variety of fault characteristics will appear. If the oil pressure is low, the part between the shaft and the bearing bush will produce dry friction due to direct contact, which will cause the moving surface to damage and damage the sensor. At this time, the shaft surface is blue. If the lubricating oil fails or the pressure cannot be built up, the moving surface will completely lose the protection of the oil film and directly contact for dry friction. When the temperature rises, the alloy layer of the bearing bush melts, and the timely shutdown will produce the phenomenon of holding the bush. If the shutdown is not timely, it will cause more serious damage to the parts

causes: the engine oil diversion to the domestic market is different in all aspects, too low or the lubricating oil passage is broken; The oil suction filter, oil passage and oil hole are blocked; The oil pump is worn or the oil suction pipeline leaks; The pressure regulating valve and pressure limiting valve are damaged; The idle running time of the engine is too long; After the engine is started, the high-speed operation and full load operation are carried out directly without heating up; After full load operation, under the condition of high temperature, the machine will be shut down without cooling by running at medium and low speed with no load, so that the heat in the engine will deposit and the temperature will rise; The standard oil is not selected and the oil is not changed regularly according to the regulations

2. There is water in the lubricating oil, causing damage and damage to the shaft and bearing bush:

the water in the lubricating oil will cause serious damage to the shaft and bearing bush, because water will deteriorate the lubricating oil and destroy the oil film. The edge of the friction surface of the alloy layer surface of the bearing bush appears porous gray objects, and black corrosion objects are formed on the alloy surface, making irregular pits and local flake spalling appear on the alloy friction surface of the bearing bush

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