Premonitory characteristics and treatment measures

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Premonitory characteristics and treatment measures of mechanical failure of diesel engine

mechanical failure of diesel engine in operation may cause damage to basic parts, or lead to major mechanical accidents. Usually, the speed, sound, exhaust, water temperature, oil pressure and other aspects of the diesel engine will show some abnormal signs before the failure, that is, the fault omen characteristics. Therefore, operators should quickly make correct judgments according to the characteristics of the omen and take decisive measures to avoid accidents

1. "Flying car" can be widely used in many paper-making enterprises in the event of loss outdoor faults

omen. The characteristic speed suddenly rises, and it is getting faster and faster. It is not controlled by the throttle. The sound is abnormal and harsh, and the exhaust pipe emits a lot of blue smoke or black smoke

"runaway" belongs to overspeed and idling, which will not happen when working under load. It is only possible when the load is suddenly removed or reduced during starting or working. The main cause of "runaway" is the failure of the regulator system, which makes the oil supply out of control or excessive oil in the oil pan. If emergency measures are not taken immediately, major accidents such as cylinder tamping and shaft breaking will eventually occur

the treatment measures are mainly to achieve the purpose of flameout by cutting off oil or gas. The emergency measures that can be taken are: first, turn off the throttle, stop oil supply, and step on the brake; The second is to block the intake pipe and cut off the entry of air; Third, quickly loosen the high-pressure oil pipe to stop oil supply; Fourth, high-grade heavy load (braking) can be used in the running of vehicle diesel engine, so that the engine stalls due to insufficient torsion

2. Sticking cylinder fault

omen characteristics: speed drop, weak operation, dull sound, ultra-high water temperature, and its indication with water temperature gauge exceeds 100 ℃

at this time, sprinkle some water on the parts, which will evaporate rapidly. The main reason is the serious water shortage and the failure of the water cooling system. If the engine is shut down immediately, cylinder sticking may occur

treatment measures idle for a period of time or turn the crankshaft off to help cool, so that the water temperature drops to about 40 ℃, and then slowly add cooling water. Be careful not to add cooling water immediately, otherwise it will cause deformation or cracks of the parts due to the sudden rapid drop of local temperature

3. Cylinder tampering fault

omen feature: there is a "click" sound at the crankcase, like the sound of a small hammer tapping on the hard floor, that is, the commonly known "cylinder knocking" oil pressure drops, which is more obvious when accelerating rapidly

tamping cylinder is a destructive mechanical failure, which is mainly caused by the loosening of connecting rod bolts or the stretching and necking of bolts, and the excessive fitting clearance of connecting rod shaft, resulting in the loosening or breaking of bolts

if there is a knocking sound, but the oil pressure is normal, it is not a sign of tamping the cylinder, and it should be considered from the adjustment of oil supply advance angle

treatment measures: immediately take the first week of November every year as the "Green Express Promotion Week" to stop for maintenance and replace with new parts

4. Bush burning fault

omen feature: the sound is stuffy, as if the load suddenly increases, the speed decreases, the oil pressure decreases, and the exhaust emits black smoke

Bush burning will lead to the locking of bearing bush and journal and flameout. The main reason is that the lubricating oil film on the surface of bearing bush is damaged, the bearing bush is in direct contact with the metal on the surface of journal, the friction temperature rises rapidly, and the surface is glued

treatment measures stop the machine immediately, remove the cover, check the connecting rod bearing bush, find out the cause, and repair and replace it

5. Broken shaft fault

omen characteristics: there is a dull knocking sound in the crankcase, and the knocking sound becomes louder when the accelerator is shocked. When idling, the parts shake seriously, and the exhaust emits black smoke

the shaft fracture is caused by mechanical fatigue at the crankshaft journal shoulder. Lubrizol: Medical TPU experts lead the material innovation of medical products, which has a gradual process from crack to fracture. When recessive fission occurs, the omen characteristics are not obvious. With the expansion of the crack, the omen characteristics become more and more obvious, and finally lead to shaft failure and flameout. If the engine stops when the shaking or knocking frequency of the throttle is consistent, it may be at the critical point of shaft breaking. At this time, remove the cover and check. Push the flywheel by hand. If the axial clearance is large and the pushing is not laborious, it indicates that the crankshaft has been broken

treatment measures stop the machine immediately for inspection if there are signs, and replace the crankshaft in time if cracks are found

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