Excavator Engine Belt Tensioner

Fault 1: "Squeezing/Buzzing" abnormal noise during cold start/idleCore reason:The tensioning wheel bearing is short of oil, worn or corroded, resulting in dry rotation and friction noise.Insufficient tension, the belt slips and rubs, making a scream; Or spring fatigue, excessive swing of the tensioning arm causing resonance noise.Mud/stones are embedded in the belt groove, causing abnormal noise when scraping the belt during operation.Solution:First, clean the foreign objects in the pulley groove, add lithium based grease to the bearing grease fitting, and if the abnormal noise disappears, maintain it according to a 200-300 hour cycle.If there is still abnormal noise after adding butter, check the bearing clearance: shake the pulley by hand, and if there is obvious clearance, replace the tensioner assembly directly.Synchronously check the belt tension. If the belt ages and becomes loose, it is recommended to replace it synchronously to avoid secondary slippage.

Fault 2: Frequent belt slippage and detachment, high water temperature/generator not chargingCore reason:The tension wheel spring is fatigued and fractured, unable to provide sufficient tension, resulting in the belt being in a relaxed state for a long time.The installation of the tensioning wheel is skewed and the belt pulley is worn, resulting in belt deviation and jumping.The belt groove is excessively worn, and the friction between the belt and the wheel groove is insufficient, resulting in slippage.Solution:Check the status of the spring: Press the tensioner arm with your hand. If the rebound is weak or unable to rebound, replace the tensioner assembly directly (the spring cannot be replaced or repaired separately).Re calibrate the installation position of the tensioning wheel: Loosen the base bolt, adjust the coaxiality between the tensioning wheel and the crankshaft/water pump pulley, and ensure that the belt runs in the same straight line without any eccentric wear marks.Check the wear of the pulley groove. If the groove bottom has been worn flat, the tensioner must be replaced, otherwise even if a new belt is replaced, it will slip.

Fault 3: Tightening wheel bearing locked, engine cannot operate normallyCore reason:Long term failure to add lubricating grease, dry grinding of bearings, and high temperature locking have resulted in the inability of the belt to drive the tensioner wheel to rotate.The bearing got stuck due to water/mud ingress, internal corrosion, and eventually locked up.The installation of the tensioning wheel is too tight, and the bearing bears additional axial force, accelerating wear and failure.Solution:Immediately stop the machine and replace the tensioner assembly. Forcefully starting the engine is strictly prohibited as it may cause belt breakage, water pump/generator stoppage, engine cylinder pulling, and scrap risks.When replacing, synchronously check whether the bearing mounting seat is deformed to avoid uneven force after the installation of the new tensioning wheel.Regular maintenance should be carried out to prevent the bearings from locking up again due to lack of oil.

Fault 4: The tensioner bracket/base is broken or looseCore reason:The tensioning wheel is subjected to long-term spring tension and belt tension, causing the base bolts to loosen and not be tightened in a timely manner, resulting in fatigue cracking of the bracket due to repeated impacts.Excessive tension force (such as inconsistent spring specifications), or incorrect or overly tight belt model, can cause long-term overload and stress on the bracket.During installation, the base bolts were not tightened to the standard torque, or there were sand holes or defects at the welding points of the bracket.Solution:Check for cracks/looseness in the bracket: If there is slight looseness, tighten the bolts again according to the standard torque; If the bracket cracks, the tensioner assembly needs to be replaced (the bracket and tensioner are integrated and cannot be repaired separately).Check the belt model and tensioner spring specifications to avoid using non original parts that may cause abnormal tension.During installation, it is necessary to tighten the base bolts according to the manual torque to prevent the bolts from loosening due to long-term vibration.

Key points of preventive maintenance (reducing the probability of failure)Regular lubrication: Every 200-300 hours, add lithium based grease to the excavator-engine-belt-tensioner bearing through a grease fitting to prevent dry wear.Synchronous replacement: When replacing the engine belt, it is recommended to check the status of the tensioner at the same time. If it has been used for more than 2000 hours, replace the assembly directly to avoid damage to other components caused by belt breakage.Working condition protection: For mining/dusty working conditions, regularly clean the sediment and gravel in the belt pulley groove to reduce eccentric wear and abnormal noise.Installation specifications: When replacing the excavator-engine-belt-tensioner, it must be ensured that it is coaxial with other pulleys, and the bolts should be tightened to the standard torque to prevent installation tilting, over tightening/over loosening.

If encountering the above faults, it is recommended to prioritize stopping the machine for inspection to avoid minor problems expanding into major faults such as engine high temperature and cylinder pulling.