When the engine of the coking generator unit suddenly accelerates, it will make a heavy and powerful metal knocking sound of "rigid, rigid, rigid", and the engine body will vibrate greatly in serious cases. This is actually the main bearing of the crankshaft of the generator set. How to diagnose it?
(1) The fixing screws of the main bearing cap are loose; (2) The wear reducing alloy of the main bearing is burnt or falls off; (3) Excessive wear of main bearing and journal and axial thrust device, resulting in excessive radial and axial clearance; (4) Crankshaft bending; (5) The oil pressure is too low or the oil is deteriorated.
(1) Listen carefully. For example, the noise increases with the increase of engine speed. When the throttle valve is shaken, the noise is obvious at the moment of refueling, which is generally the main bearing is loose; If the noise is obvious when the engine is running at idle speed or low speed, and it appears disorderly at high speed, the crankshaft may be bent; If the engine body vibrates greatly at high speed and the oil pressure decreases significantly, the main bearing is generally loose, burnt or the anti-wear alloy falls off.
(2) Auscultate from the oil filling port. Open the oil filler cap, listen carefully from the oil filler, and change the engine speed repeatedly for test. If the main bearing rings, you can obviously hear the heavy and powerful metal knocking.
(3) Auscultation with stethoscope. Touch the stethoscope or self-made simple stethoscope rod at the positions of both sides of the crankcase of the engine body flush with the crankshaft axis for stethoscope while the throttle opening is constantly changing. The position with strong sound is the main bearing.
(4) Fire break test. Loosen the high-pressure oil pipe joint. If the noise is obviously reduced after cylinder 1 is disconnected, it is the first main bearing; If the sound of the last cylinder is obviously reduced after the fire is cut off, it is the sound of the last main bearing; If the sound of any two adjacent cylinders breaking fire at the same time is significantly reduced, it is the main bearing sound between the two cylinders. The sound generated by the axial movement of the crankshaft does not change when the single cylinder is cut off.
(5) Step on the clutch pedal for test. Press the clutch pedal and keep it still. If the noise is reduced or disappears, it is the noise caused by the axial movement of the crankshaft.
(6) Speed reduction test of coking machine. When diagnosing the main bearing sound of the coking machine, in order to avoid the interference of the fire knocking sound, the method of increasing the stroke of the oil supply rod and then quickly retracting can be adopted. If the sound of "hard, hard, hard" is heard while the engine is slowing down, it may be the main bearing sound. At the same time, the oil filler cap should be opened, assisted by auscultation and cylinder oil cut-off method, so as to facilitate diagnosis.
How to diagnose the crankshaft main bearing noise of coking generator set? We have explained the content of the question from five aspects above. You can use it as a reference. For more questions, please visit our website http://www.digiscrappin.com Consult.