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The sound of the tractor comes from the vibration and friction of the moving parts. When the tractor is used for a long time, pistons and cylinders, journals and bearings, valve and valve seats, and gears and gears are seriously worn, resulting in loose and loose gaps, or due to poor repair quality, improper adjustment and inability Correct use, etc., will often cause abnormal sound of the tractor, which will increase the wear and damage of the parts, and even cause accidents. So we must diagnose in time and adopt effective measures to solve it. The tractors have abnormal sounds, and the problems are often complicated and the phenomenon is various. Different types of faults sometimes reflect the same noise, and the same fault may not reflect the same in different models. Sometimes normal sounds and special noises are mixed and difficult to distinguish. However, after careful research and analysis and scientific analysis, we can find out its regularity through the appearance of phenomena. According to the practice, the author gives the main reason for the abnormal sounding of the tractor, the characteristics of the noise, the timing and the law of change, and analyzes the cause of the abnormal sound, and diagnoses and eliminates it. First, the main bearing knocking sound phenomenon: This is a kind of heavy and boring [é•—, é•—] knocking sound, the faster the engine speed, the sound is louder, when suddenly increasing the throttle, there is heavy [When, when] The sound. And the noise increases as the engine load increases. Reasons: (1) Loosening of bearing cover fixing screws; (2) Insufficient or excessive lubricating oil supply in the bearing, frictional overheating, burning or detachment of the bearing alloy; (3) Serious friction of bearing bushes and journals. The clearance is too large, causing looseness; (4) The axial clearance of the crankshaft is too large. Diagnosis: Listen to the sound in the crankcase, open the oil filler cap, listen carefully from the oil filler port, and repeatedly change the engine speed test. Increase the throttle and reduce it quickly. If you hear a solid and heavy [é•—, é•—] tapping when the engine speeds down, there may be a main bearing ring. Jitter-enhancement throttle test - Makes the engine run at a lower speed, slightly jogs the throttle by hand, and repeatedly throttles the throttle. If the sound is increasing with the increase of the engine speed, the throttle sound when the accelerator throttle is more obvious, this is generally indicated that the main bearing is loose; if the engine is running at idle, the sound is more obvious, high speed If it becomes cluttered, it may be crankshaft bending. If the crankshaft is bent at high speed, the oil pressure is significantly reduced, which means that the bearing is loose or burned, and the alloy falls off. Auscultation with a screwdriver - When the throttle is not changing, one end of the driver is touching the two cylinder blocks, and the horizontal position of the crankshaft is more obvious. From the louder part of the sound can be judged that the road bearing abnormal sound. Step clutch pedal test - According to the phenomenon that the phenomenon is caused by the sound of the axial clearance is too large, the clutch pedal is depressed, the sound immediately weakened or disappeared, this time can be determined that the axial gap is too large. Exclusion: When the diagnosis is that the main bearing sounds, it should be promptly removed. First check the oil pan and bearing cap. When necessary, the engine can be dismantled and overhauled. If the clearance is too large, but the tile and journal surface meet the technical requirements, the gasket can be properly adjusted to restore normal clearance. If the journals and bearings are severely worn or burned, the main journals should be worn and the size of the bearings repaired accordingly. Second, the connecting rod bearing knocking sound phenomenon: It is a kind of lighter than the main bearing knocking sound, ease and short [when, when] sound. When suddenly accelerating, there was a continuous and distinct knocking sound. There is no change in the sound when the engine temperature changes. Reasons: (1) Loosening or breaking of the fixing screws of the connecting rod bearing cover; (2) Burning or dropping of the bearing alloy; (3) Abrasive wear of the bearing and journal, and excessive radial clearance. Diagnosis: The knocking sound of the connecting rod bearing is judged better than the knocking sound of the main bearing, and its noise is lighter than the knocking sound of the main bearing. It is very clear at the oil port. In severe cases, it can be heard near the engine, and the higher the engine speed is, the louder the sound is. When the throttle is suddenly increased, it is even more prominent, and the percussion sound is continuously emitted. If the multi-cylinder engine cylinder rod bearing knocking sound, you can use [broken cylinder method] for diagnosis. When a cylinder [broken oil] (high-pressure tubing connector loosen), the sound significantly weakens or disappears, indicating that the sound is at the cylinder rod bearing. Exclude: engine connecting rod bearing different response in a timely manner to eliminate, otherwise, the link screw may break off, connecting rod out, to break the cylinder block, etc., resulting in accidental damage. When the connecting rod bearing sound is severe, the crankshaft connecting rod journal should be worn and the size of the bearing bush repaired accordingly.