EN
en
FR
nl
ka
ru
fa
ar
az
pl
uk
hy
tr
mk
de
pt
el
es
it
sq
ky
Tips for Choosing a Good Used Excavator
1. Methods for purchasing second-hand excavators
(I) Check the bucket and boom
1. Comprehensive working condition considerations: Excavators have a variety of uses. In addition to excavation, they are also often used for operations such as piling and laying pipelines. Therefore, it is necessary to fully check the condition of the bucket, including the integrity and functionality of the piling, crushing and walking devices. For example, if the bucket has been used for frequent crushing operations, its bucket teeth and bucket walls may be severely worn or deformed, affecting the subsequent use effect and work efficiency.
2. Inspection of key connection parts: The tightness of the bucket cylinder connection pin and bushing is crucial. Long-term use and neglect of maintenance can easily cause these parts to loosen, causing equipment failure. The reliability of the connection should be carefully checked. If there is looseness, the cost and difficulty of repair need to be further evaluated. In addition, the connection between the rear arm and the excavator should not be ignored. Excessive wear may cause the connection to fail, or even make the entire equipment lose its use value. If the connection part is severely deformed, cracked, or the wear exceeds the specified limit, it should be treated with caution.
(II) Check the hydraulic cylinder and oil pipe
1. Check the sealing of the hydraulic system: Oil leakage is a serious hidden danger of the hydraulic system, which may cause the entire oil circuit to be polluted. Check the chrome-plated surface of the hydraulic cylinder, which should be free of scratches, dents, and traces of oil leakage. Once hydraulic oil seepage is found, it indicates that dust is very likely to have invaded the hydraulic system, accelerating system wear and failure. For example, in a dusty construction site, if the cylinder is not tightly sealed, dust will mix with the hydraulic oil after entering, forming sludge, blocking the oil circuit, and affecting the normal operation of the cylinder.
2. Cylinder wall integrity check: Confirm that the cylinder wall is not damaged or dented. Due to the small gap between the cylinder and the cylinder wall, tiny debris in the pipeline may cause a large amount of metal chips to be produced due to wear during the operation of the cylinder, thereby polluting the hydraulic system. Professional tools or experience can be used to judge the smoothness and flatness of the cylinder wall, such as touching it with your hands to feel whether there are abnormal protrusions or depressions, or using an endoscope to check the internal situation.
(III) Pay attention to the welding parts of the body
1. Inspection of welding marks and cracks: Carefully check all parts of the excavator body to see if there are cracks and non-original welding marks. These abnormalities often indicate that the machine has been overused or repaired after a major accident. For example, welding marks on key structural parts, such as the frame and boom, may mean that the part has been subjected to excessive stress or damage, and its structural strength and stability have been affected.
2. Structural deformation detection: Place a straight plate at the rear arm and the dipper position to check for misalignment or distortion. If so, it means that the equipment may have experienced severe impact or long-term unreasonable use, which will affect the operation accuracy and equipment life. At the same time, pay attention to the repair of excess steel plates on the body. Although too many patches may repair local damage, it also implies that the equipment has been used for a long time and may have more potential problems, such as internal structural corrosion and fatigue damage.
(IV) Check the rubber tracks and chassis
1. Rubber track wear assessment: The rubber tracks of small excavators are used in special scenarios, and their wear is often overlooked. When checking, pay attention to the cracks and edge wear on the rubber tracks, similar to the tire tread inspection. For example, if there are many cracks on the track and the depth is large, or the edge wear is severe and serrated, it means that the track is close to the end of its service life or the use environment is harsh. At the same time, observe the wear of the sprocket and the supporting wheel, because the rubber track interacts with them, and excessive wear on one side will accelerate the damage of the other side.
2. Chassis component inspection and oil level confirmation: When checking the tracks and chassis, check the oil level and cleanliness. This part is easy to be overlooked, but it is very critical. If the oil volume is low and mixed with water or impurities, it will cause a series of problems, such as poor lubrication leading to increased component wear, engine overheating and even damage. The oil level and quality can be checked through the oil dipstick to observe whether the oil color is normal, whether there is emulsification, and whether the oil contains impurities such as metal debris.
(V) Driving operation inspection
1. Crawler travel device flow detection: After the engine is preheated and started, let the machine stand on only one side of the crawler, and rotate the two sides in turn, record the number of actions completed within a specific time (such as 30 seconds or 60 seconds), and compare with other crawlers. The crawler travel device of the excavator is equivalent to a built-in flow meter. If the flow on both sides is different, it indicates that there is a problem, such as crawler motor failure, oil circuit blockage or leakage, which will affect the stability and power output of the equipment.
2. Slewing mechanism inspection: Drive the excavator in a straight line for 10 meters on flat ground, check its walking linearity, and judge whether the running conditions of the travel devices on both sides are consistent. At the same time, check the slewing gear ring and slewing bearing. Under normal circumstances, the upper structure should be able to start the slewing smoothly and stop accurately with minimal deviation. For small excavators, the life of the slewing gear ring and slewing bearing is usually equivalent to that of the machine. If the slewing is not smooth, there is an abnormal sound or a large shake, be alert to whether there is a fault in this part, such as gear ring wear, bearing damage, etc.
(VI) Check the engine hood
1. Check the engine exhaust condition: Open the engine hood and check whether the exhaust pipe is smoking. Pull out the oil dipstick to check if there is any smoke. If there is too much smoke, it usually means that the piston ring needs to be replaced and the engine may need an overhaul soon. For example, blue smoke indicates that the cylinder piston ring and cylinder barrel are seriously worn, causing oil burning; white smoke may be caused by damage to the cylinder gasket, allowing water vapor to enter the exhaust system; black smoke may be caused by damage to the injector and incomplete fuel combustion.
2. Check the engine auxiliary system: Check the air filter and all pipes and pipe clamps to ensure that no dust enters the engine. Even a small amount of dust can destroy the engine. Pay attention to dust or dirt accumulated at the terminal. Check the tightness of the fan belt to ensure that it works properly and provides good protection for engine heat dissipation. Check the cleanliness of the radiator to prevent engine overheating due to poor heat dissipation and shorten the life of the machine. In addition, it is also necessary to check the radiator fluid and engine oil level and quality, check the degree of battery corrosion, and check whether there are obvious leaks around the engine, such as coolant leakage, oil leakage, etc., which may affect the normal operation of the engine and the overall performance of the equipment.
2. Precautions for purchasing second-hand excavators
(I) Look at the vehicle condition instead of the time
Most buyers pay too much attention to the time table reading when purchasing second-hand machines, and believe that the shorter the hour meter time is, the better the vehicle condition is. This concept is influenced by the habit of looking at the mileage in the automotive industry, but the excavator hour meter time may not be true. Some equipment may not accurately reflect the actual use of the hours due to hour meter failure, human tampering, or re-activation after long-term idleness. Therefore, the purchase of a second-hand excavator cannot be judged only by time. The vehicle condition is the key, such as the overall structural integrity of the equipment, the degree of wear of each component, the hydraulic system and the engine performance, etc., which should be comprehensively evaluated.
(II) Pay attention to the actual wear and tear
1. Wear analysis of key components: chain plates, supporting wheels, and the reinforcement ribs on the inner side of the forearm close to the bucket can accurately reflect the use history of the excavator. For excavators working in mines, the wear degree of these three parts is much higher than that of earthmoving excavators under the same number of hours. The working environment of mines is harsh, the chain plate and chain spikes are unevenly worn and have abrupt scars, there are rock knock marks on the metal surface, and the inner reinforcement ribs of the forearm are obviously damaged; while these parts of earthmoving excavators are more delicate and smooth, and it is difficult to see large-scale rock knock marks. For example, for excavators working on hard ore beds, the chain plates may be severely deformed and worn due to frequent contact with ore, the supporting wheels may be damaged due to large impacts, and the reinforcement ribs may be dented or broken due to ore impact; while for earthmoving excavators in urban construction, these parts are mainly subjected to soil friction, and the wear is relatively light.
2. The impact of wear on cost and benefit: Purchasing earthmoving excavators can reduce maintenance and repair costs and increase benefits. Due to the serious wear and tear of mining excavators, the subsequent maintenance frequency is high and the cost is high, and the safety and efficiency of the operation may be affected by the decrease in structural strength; while the structure of earthwork excavators is relatively complete and the performance is stable. They can maintain good working conditions for a long time, reduce operating costs and improve economic benefits.
(III) Pay attention to various indicators of the engine
1. Appearance and oil inspection: First check the appearance of the engine to see if there is a large area of water leakage or oil leakage, whether the antifreeze and engine oil are missing, and whether the oil filter is an original accessory. If the owner carefully maintains the engine during maintenance and uses the manufacturer's genuine accessories on time, it can greatly reduce the wear of components and extend the service life of the engine. For example, non-original oil filters may have poor filtering effects, causing impurities to enter the engine and accelerate component wear; the lack of antifreeze may cause poor heat dissipation of the engine and cause high temperature failures.
2. Performance inspection after starting: After the engine is started, observe whether the idle speed is stable and whether the lower exhaust is too large. Unstable idle speed may be caused by internal engine failures, such as fuel system failures, poor valve sealing, etc.; excessive lower exhaust may mean that components such as piston rings and cylinder liners are severely worn. In addition, observe the color of the engine smoke to determine the type of fault. Blue smoke means burning oil, white smoke may be caused by cylinder gasket damage, and black smoke may be caused by injector damage. These faults will affect engine performance and reliability, increase maintenance costs and use risks.
In summary, when purchasing a second-hand excavator, it is necessary to comprehensively and carefully check all aspects of the equipment, from bucket boom to hydraulic system, from body welding to crawler chassis, from engine to operating performance, and pay attention to purchase precautions, not just relying on time, but also focusing on real wear and tear and engine conditions. Only in this way can we select equipment that meets the needs, is cost-effective, and can work stably and reliably from many second-hand excavators, provide strong guarantees for engineering construction, and maximize investment benefits.