If a mechanical diesel engine malfunctions during operation, the basic components will be damaged, and heavy machinery accidents will occur. Under normal circumstances, before the failure of the diesel engine, its speed, sound, exhaust, water temperature, oil pressure and other aspects will show some abnormal signs, that is, the characteristics of the symptoms of the failure. Therefore, operators should promptly make correct judgments based on the characteristics of the signs and take decisive measures to avoid accidents.
First, the "speed" fault. (1) Predictive features: The sudden increase in speed, and faster and faster, is not controlled by the throttle, the sound is abnormal, harsh, exhaust pipe emits a lot of blue smoke or black smoke.
(1) "Speed ​​coaster" is idling at speed, and it will not happen under load. It will only happen if the load is suddenly removed or reduced during the start or work. The main reason is the failure of the governor system, which results in loss of control of the oil supply or excess oil in the sump. There are signs of "speed racing". If emergency measures are not taken immediately, it will eventually lead to major accidents such as blow-by-cylinder and broken shafts.
(2) Treatment measures: The purpose of extinguishing the fire is mainly by cutting off oil or gas. The emergency measures that can be taken are: First, stop the fuel supply to stop the accelerator and step on the brake; second, block the intake pipe and cut off the air; third, quickly release the high pressure fuel pipe to stop the fuel supply; and 4) use the diesel engine during walking. High-grade heavy load (brake) makes the engine turn off due to insufficient torque.
Second, sticky cylinder failure.
(1) Predicting features: Decrease in speed, inability to operate, dull sound, and high water temperature. Its indication with a water temperature gauge exceeds 100°C. At this point, sprinkle some water on the parts and quickly evaporate. The main reason is the severe lack of water and the failure of the water cooling system. If the flameout stops immediately, a sticky cylinder may be produced.
(2) Treatment measures: Idle operation for a period of time or turn off the crankshaft to help cool the water, reduce the water temperature to about 40°C, and slowly add cooling water. Be careful not to add cooling water immediately, otherwise it will cause the parts to be deformed or cracked due to the sudden drop in local temperature.
Third, faulty cylinder.
(1) Precursor features: There is a “click†sound in the crankcase, and a sound like a small hammer taps hard floor, which is commonly known as “knocking sound†and the oil pressure drops. Cylinder is a destructive mechanical failure, the main reason is due to the loose connecting rod bolts or bolts stretching telescopic neck, connecting rod shaft with the gap is too large, resulting in loose bolts or broken due to. If a cylinder knocks, but the oil pressure is normal, then it is not a sign of slamming, and should be considered from the perspective of adjusting the fuel advance angle.
(2) Treatment measures: stop and overhaul immediately and replace new parts.
Fourth, tile failure.
(1) Precursor features: The sound is boring, as if the load suddenly increases, the speed decreases, the oil pressure drops, and the exhaust smokes black smoke. Burning tiles will cause the bushes and journals to lock and extinguish due to the fact that the lubricant film on the surface of the bearing bush is damaged, the bearings and the metal on the surface of the journal are in direct contact with each other, the friction temperature rises rapidly, and the surface is glued.
(2) Treatment measures: Stop the machine immediately, remove the connecting rod and bearing, check the cause, and repair and replace.
Five, broken shaft failure.
(1) Predictive features: A boring percussive sound occurs in the crankcase. The sensation of the throttle increases the knocking noise. When the idling speed runs, the machine shakes badly and the exhaust emits black smoke. The broken shaft is caused by mechanical fatigue at the crankshaft neck shoulder and has a gradual change from cracking to breaking. When the latent fission occurs, the characteristics of the omens are not obvious. As the cracks expand, the features of the omens become more and more obvious, and finally the axis breaks down. If there is a throttle, such as a throttle, or when the knock frequency matches, it may be at the critical point of the broken axis. At this point, the cover is inspected and the flywheel is pushed by hand. If the axial clearance is large, and the pushing is effortless, it indicates that the crankshaft has been broken.
(2) Treatment measures: It was found that the omen was immediately checked for shutdown and it was found that the crankshaft should be replaced in time.
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