Excavators are widely used in earthwork, mining, infrastructure construction and other fields, and their working environment is harsh, with heavy load and long continuous operation time, so various mechanical and hydraulic faults are prone to occur after long-term use. The stability of the excavator directly affects the progress and efficiency of the project. This guide will focus on the common faults of excavators such as hydraulic system failure, walking weakness, abnormal rotation, engine abnormalities and chassis wear, elaborate detailed troubleshooting steps, professional repair methods and standardized long-term maintenance plans, helping maintenance personnel quickly solve faults and reduce equipment failure rates.
The hydraulic system is the core component of the excavator, and more than 70% of excavator faults come from the hydraulic system, mainly including slow movement, weak lifting, hydraulic oil leakage, abnormal noise and high oil temperature. Slow movement and weak lifting are the most common hydraulic faults, mainly caused by insufficient hydraulic oil, clogged filter element, worn hydraulic pump, faulty control valve or internal leakage of oil cylinder. First, check the hydraulic oil level: insufficient hydraulic oil will cause air to enter the system, resulting in cavitation, slow movement and weak power. Replenish the hydraulic oil to the standard scale mark in time, and ensure that the hydraulic oil brand and model meet the manufacturer's requirements. Secondly, check the hydraulic filter element: long-term use will lead to clogging of the suction filter, return filter and pilot filter, restricting oil flow and reducing system pressure. Replace all hydraulic filter elements regularly according to the operating hours, and it is strictly forbidden to use unqualified filter elements to avoid impurities entering the system and wearing components.
The wear of the main hydraulic pump is the main cause of insufficient system pressure and weak operation. The main pump is the power source of the hydraulic system. Long-term high-load operation will lead to wear of piston slippers, swash plate and cylinder block, resulting in internal leakage and reduced output pressure. Use a hydraulic pressure gauge to test the main pump output pressure. If the pressure is lower than the standard value (usually 32-35MPa for medium excavators), the main pump needs to be disassembled and overhauled. Replace the worn piston, slipper and swash plate, and reassemble and debug to restore the normal pressure of the main pump. In addition, the spool of the main control valve is stuck or worn, which will lead to uneven oil distribution and slow movement. Clean the main control valve spool with professional cleaning agent, remove impurities and sludge, and replace the worn spool to ensure flexible sliding of the spool.
Hydraulic oil leakage is divided into external leakage and internal leakage. External leakage is mostly caused by damaged oil pipe, aging seal ring and loose joint. Check all hydraulic oil pipes for cracks, wear and damage, replace the damaged oil pipes in time, tighten all pipe joints, and replace the aging seal rings and gaskets. Internal leakage mainly occurs in the oil cylinder, hydraulic motor and main valve, which is difficult to observe directly but will lead to reduced efficiency and weak operation. For the boom, bucket and stick oil cylinders, check whether there is oil stain on the cylinder rod. If there is oil stain, it means the oil cylinder seal is damaged. Disassemble the oil cylinder, replace the seal kit and dust ring, and check whether the cylinder rod is scratched. Deep scratches will damage the new seal, and the cylinder rod needs to be polished or replaced.
High hydraulic oil temperature will accelerate the aging of seal rings, deteriorate oil quality and reduce component life, mainly caused by poor heat dissipation, long-term overload operation and insufficient oil. Clean the hydraulic radiator regularly to remove dust, sand and debris on the surface, ensure smooth heat dissipation, and avoid using high-pressure water to wash to avoid damaging the radiator fins. Avoid long-term overload operation of the excavator, reduce continuous high-load operation time, and let the equipment rest appropriately to control the hydraulic oil temperature within the normal range (30-80°C). Replace the hydraulic oil regularly according to the operating hours (usually every 2000 hours). Use high-quality anti-wear hydraulic oil, and it is strictly forbidden to mix different types of hydraulic oil to avoid chemical reactions and deterioration.
Excavator walking weakness and deviation are common faults of the walking system, which affect the construction efficiency and operation safety. The main causes include uneven track tension, worn walking motor, faulty walking brake, clogged walking valve and insufficient hydraulic pressure. First, adjust the track tension: too tight or too loose track will lead to walking weakness, deviation and accelerated wear. The track tension is adjusted by the tensioning cylinder, and the appropriate sag is about 20-30mm. Secondly, check the walking motor and reducer: worn gears and bearings in the walking motor and reducer will lead to weak walking and abnormal noise. Disassemble and inspect, replace the worn gears and bearings, and replenish the reducer gear oil. Then check the walking brake: if the brake cannot be fully released, it will cause walking resistance and weakness. Adjust the brake clearance and replace the worn brake pads.
Abnormal rotation of the upper platform, such as slow rotation, stuttering and deviation, is mostly related to the rotation motor, rotation brake and rotation reducer. The main causes include internal leakage of the rotation motor, faulty brake, worn gear and insufficient lubricating oil. Check the rotation motor for internal leakage, repair or replace the faulty motor; adjust the rotation brake to ensure flexible release and tight braking; check the gear wear in the rotation reducer, replace the worn gears, and replenish the gear oil to the standard level. At the same time, clean the rotation bearing regularly, remove impurities and add lubricating grease to ensure smooth rotation.
Engine faults of excavators are similar to those of loaders, mainly including overheating, insufficient power, abnormal noise and difficult starting. The troubleshooting and repair methods are consistent with those of loader engines, focusing on cleaning the radiator, checking coolant and engine oil, replacing filter elements, and maintaining the fuel system. For the chassis components such as track shoes, idlers, supporting wheels and driving wheels, check the wear regularly, clean the sediment and debris on the chassis after each shift, and add lubricating grease regularly to reduce wear and extend the service life of chassis components.
Long-term standardized maintenance is the fundamental measure to reduce excavator faults. Establish a strict daily, weekly and monthly maintenance system: check oil, water, circuit and track tension before each shift; clean the equipment, check for oil leakage and loose bolts after each shift; weekly maintenance includes cleaning filters, lubricating each component, and checking belt tension; monthly maintenance focuses on replacing oil products, checking component wear and adjusting clearances. At the same time, standardize the operation of drivers, avoid violent operation, overload operation and long-term idling, and reduce mechanical wear. Through scientific maintenance and correct use, the failure rate of excavators can be greatly reduced, the service life can be extended, and stable and efficient operation can be ensured.
