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Trouble and elimination of abnormal noise of excavator

by:Laike     2020-07-24
The abnormal sound of the drive axle is a manifestation of the deterioration of the technical condition. The size of the sound indicates the degree of deterioration of the technical headquarters. The unusual sound and timing of the rear axle are also different. The abnormal noise usually changes with the change of the driving speed and driving conditions of the excavator.

1. Reason analysis:

(1) Gear wear When the excavator is running, the reducer (main reducer and wheel reducer) and differential gear of the drive axle will wear out. When the lubrication is poor, the gear wears faster. The gear teeth lose their involute geometry when they are worn. When the gears are meshed, the rolling friction is reduced and the sliding friction is increased. This not only increases the meshing clearance of the gears, but also further accelerates the gear wear process and generates noise. , That is abnormal sound. In addition, the gear teeth are directed to a cantilever beam, and the bending stress generated at the tooth root is the largest after being loaded. In addition to the influence of the alternating load, fatigue cracks often occur at the root of the gear. With the extension of working time, the degree of fatigue increases and the cracks expand; when the gear teeth are engaged, the lubricating oil will be squeezed into the cracks of the meshing teeth, and the cracks extend to the depth and length under the action of the oil pressure. When the bearing capacity of the gear is less than the load, it will break, commonly known as beating. After beating, the abnormal noise will be louder, and it may even interrupt the transmission or destroy other mechanical parts. ---Human excavator drive wheel manufacturer

(2) The rear axle gears and planet gears of the differential are lined with pads. The thinning of these pads will increase the differential gear meshing clearance, so abnormal meshing occurs during work and makes a noise.

(3) The wear of the half shaft spline teeth will also increase the fit clearance. During transmission, when the rotational speed difference between the two cooperating parts occurs, an abnormal sound will be produced when the spline and the keyway collide.

(4) Influence of bearings Bearings bear more alternating loads, which not only produce wear during operation, but also fatigue the rolling elements and raceway surfaces; when the lubrication is poor, the damage speed is accelerated and the damage degree is worsened, so the rolling of the bearings When the body is rolling, the vibration noise produced by irregular rolling is produced; the preload of the tapered bearing is adjusted by the gasket or the thread (differential bearing). If the adjusted preload is too small, it will make the cone The axial movement of the gear causes the meshing gap to be large and small, and the proper meshing is lost and an abnormal noise is produced. The sound is louder when damaged, and even the moving parts will be stuck. ---Human excavator drive wheel manufacturer

(5) The tightening (bolts) of the reducer and differential are loose, and there will be abnormal noises.

(6) Poorly lubricated gears must be lubricated during gear transmission. If there is a lack of oil or the poor quality of the oil product does not form an oil film, and dry friction occurs when the gear teeth are engaged, an abnormal noise will be emitted.

(7) When the main reducer and differential of the drive axle are not properly assembled, there should be a certain gap between the matching parts of the gear and the bearing. An excessively large gap produces an abnormal noise; the gap is too small, and the oil film on the gear teeth of the gear is easily squeezed when the gears are meshed, which affects the lubrication and cooling of the tooth surface, causing the metal tooth surface to directly contact, forming dry friction to generate high heat, and instantaneous high temperature during transmission. The two tooth surfaces that are meshed will stick together, and the metal tooth surfaces will form scars in the direction of relative sliding, which is called bite sticking. At this time, the gear works and is not stable, generating a lot of vibration and noise. ---Human excavator drive wheel manufacturer

When the main and passive gears of the reducer are engaged, there should be a correct engagement mark to ensure good engagement. If the meshing marks of the gear teeth are not evenly distributed around the pitch circle line, the excavator will make abnormal noises when driving.

2. Diagnosis and elimination:

When diagnosing, it should be ruled out based on the timing and characteristics of abnormal sounds, combined with the reasons for the above analysis.

(1) The road test excavator has abnormal noise when driving straight, and the fault is generally at the main reducer or differential bearing; when the corner appears abnormal noise, the fault is mostly in the differential.

① If the noise is high (screaming) and it is a new assembly, the differential part of the axle housing driven by the hand mold has a hot and unbearable feeling, which indicates that most of them are caused by too tight assembly and too small gap between each fit.

②If the noise occurs after using it for a long time, it is generally caused by the wear of various parts and the fitting gap is too large. It is often expressed as a 'pop' sound when starting or when the speed of the car changes. If the dry friction sound is heard, it is mostly due to poor lubrication in the drive axle.

(2) Reliable feel or clearance measuring instrument is used during parking inspection.

①Check the total transmission clearance of the drive axle with the clearance measuring instrument, the method is: put the transmission lever in the neutral position, release the parking brake, brake the wheels, and fix the scale of the clearance measuring instrument on the reducer shell The pointer is fixed on the connecting flange of the transmission shaft. Rotate the drive shaft to make the drive shaft turn from one limit position to another limit position, and the measured angle value is the total angular clearance of the drive axle transmission, that is, the final gear meshing clearance, differential gear meshing clearance, half shaft and The sum of the fit clearance of the half shaft gear and the meshing clearance of the wheel reducer gear should generally be around 65°C. If the measured angle is too large, it indicates that the abnormal noise of the drive axle is due to the large clearance of the transmission mechanism. To. ---Human excavator drive wheel manufacturer

②Check the lubrication situation. Remove the oil level plug and check the height of the oil level. If there is excessive oil shortage or oil deterioration, it means that the abnormal noise is caused by poor lubrication.

③ Check the temperature When driving the drive axle and hear a high-pitched sound, you can touch the temperature of the drive axle main reducer case, differential case and wheel side reducer case with your hands. If there is overheating, it indicates that the assembly is too tight. Generally, this phenomenon occurs in the new or repaired drive axle. ---Human excavator drive wheel manufacturer
When it is finally diagnosed that the drive axle is malfunctioning, it should be disassembled and checked, and the symptom eliminated. For example, when the bearing is inspected for damage after disassembly, it should be replaced. If the preload is small, it should be adjusted according to the actual situation. The main reducer or the differential meshing gap is too large, or the meshing mark is incorrect. Adjust it. When adjusting the indentation mark, please refer to the adjustment method of the loader's indentation mark. When the gear teeth are damaged, it is more ghostly. Generally, the gears should be replaced in pairs. If it is not replaced in pairs, not only will there be abnormal noise after replacement, but also the service life of the gear.
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