Common causes and inspection methods of abnormal noise caused by engine vibration of excavator
Fault details: when a Carter excavator is working, the engine has a crackle. If the engine speed increases, the crackle will be greater When working, I found that there was a noise when the engine was running at a low speed, but the noise was greater when the engine speed was increased, and I could feel the engine vibration in the cab
Fault phenomenon analysis:
In general, there are two kinds of fault manifestations of excavator engine rattle: one is the abnormal sound of piston ring knocking and the other is the abnormal sound of piston ring air leakage First, let the engine run at low speed, shake the accelerator by hand and repeatedly increase the accelerator. It was found that the fault phenomenon was' the sound was heavy and dull, and it increased with the increase of the engine speed. When the accelerator was shaken, the instant sound of refueling was obvious, and at the same time, the engine body vibrated '. Therefore, the maintenance master determined that the main bearing sounded
Abnormal knocking sound of piston ring
If the piston ring groove is worn, the piston ring is loose in the ring groove The piston ring is broken. The piston ring hits the cylinder port step This is because the cylinder wall is greatly worn, and an obvious step is formed between the non worn part and the severely worn part on the top of the cylinder liner. At this time, if the clearance between the connecting rod bearing and the connecting rod bushing is large, the piston ring and the step will collide due to the inertial force when the piston moves to the top dead center, resulting in a "pop, pop" sound. When the fault is serious, the piston ring will be broken or broken
Air leakage and abnormal noise of piston ring
Grooves appear after the cylinder wall is worn. After the cylinder and piston ring are worn, the opening clearance of the piston ring is too large. The piston ring is of poor quality or out of roundness. The elasticity of the piston ring is too weak. Due to carbon deposition, the piston ring is stuck in the ring groove and loses its seal
Maintenance idea:
Open the oil filler cap for inspection. If the light blue smoke is emitted Pulsatively, and the frequency is consistent with the sound; During the cylinder breaking test, if the blow by is weakened, the piston leaks and makes abnormal noise. Carry out the cylinder breaking test of the single cylinder of the engine If the noise decreases but does not disappear when the engine is broken, put the long handle screwdriver on the upper part of the piston to listen carefully. If there is a "Shua, Shua" sound, it means that the piston ring is broken. If there is obvious vibration, it means that the piston ring collides with the step at the cylinder mouth, causing the excavator engine to make abnormal noise and the engine to crack When the engine temperature is low, it will make a "bang, bang" sound, and the sound will increase when the speed increases; After the engine temperature rises, the noise gradually decreases or disappears; The noise disappears during the single cylinder fire cut-off test, and then reappears after the work is resumed. It can be concluded that the piston leaks and makes abnormal noise. After disassembling the engine, it is found that the crankshaft bearing is seriously worn. Fault maintenance method: re select and replace the bearing, and test the machine to eliminate the fault.
