Excavator maintenance method steps
1, the engine speed drops.
First, test the output power of the engine itself. If the output power of the engine is lower than the rated power, the fault causes may be poor fuel quality, low fuel pressure, incorrect valve clearance, engine cylinder not working, incorrect fuel injection timing, incorrect fuel quantity setting, air leakage in the intake system, defects in the brake and its joystick, and carbon deposition in the turbocharger. If the engine output power is normal, it is necessary to check whether the flow of the hydraulic pump does not match the engine output power.
The speed of hydraulic excavator is inversely proportional to the working load, that is, the product of the flow and the output pressure of the pump is constant, and the output power of the pump is constant or close to constant. If the pump control system fails, the best load matching state of the engine, pump and valve under different working conditions cannot be realized, and the excavator cannot work normally. This kind of fault should start with the electrical system, then check the hydraulic system and finally check the mechanical transmission system.
2. Slow working speed
The main reason for the slow working speed of the excavator is that the engine power decreases due to the wear of all parts of the whole machine, and the hydraulic system leaks. Hydraulic pump of excavator is a kind of plunger variable pump. After the pump works for a certain period of time, its internal hydraulic components, such as cylinder, plunger, port plate, nine-hole plate and turtle back, will inevitably wear excessively, resulting in internal leakage and uncoordinated parameters, resulting in insufficient flow, high oil temperature and slow working speed. At this time, it is necessary to overhaul the whole machine and repair and replace the worn parts.
However, if the excavator working for a long time does not suddenly slow down, it is necessary to check the following aspects. First, check whether the circuit fuse is open or short-circuited, then check whether the pilot pressure is normal, then check whether the servo control valve-servo piston is stuck, and whether the distributor confluence is faulty. Finally, disassemble the hydraulic pump for data measurement to confirm the problem of the excavator.
3. The excavator is weak.
Insufficient digging force is one of the typical faults of excavators. There are two situations when you can't dig: one is that you can't dig, the engine is not stuck, and the load is very light; The second is weak excavation. When the boom or stick reaches the finish line, the engine will be severely stuck or even shut down.
(1) The excavation is weak, but the engine does not press the car. The digging force is determined by the output pressure of the main pump, and whether the engine is stuck depends on the relationship between the absorption torque of the oil pump and the output torque of the engine. The engine is not stuck, indicating that the oil pump absorbs less torque and the engine load is light. If the working speed of the excavator is not obviously abnormal, mainly check the maximum output pressure of the main pump, that is, the system overflow pressure. If the measured value of the overflow pressure is lower than the specified value, it means that the setting value of the overload overflow valve in the hydraulic circuit of the mechanism is incorrect, which leads to the premature overflow of the mechanism and the failure to work. You can adjust the machine by turning the adjusting screw.
(2) The excavation is weak and the engine is stuck. Engine stall indicates that the absorption torque of the oil pump is greater than the output torque of the engine, resulting in engine overload. This kind of fault should first check whether the engine speed sensing system is normal, and the inspection method is similar to the engine inspection method mentioned above. After the above detailed inspection and troubleshooting, the engine speed sensing system will return to normal function, the engine stalling phenomenon will disappear and the digging force will return to normal.
4. Causes of "trip stop"
1, the variable speed transmission mechanism is worn. W4-60 excavator adopts mechanical shift transmission mechanism. This transmission mechanism relies on the axial movement of the sliding gear sleeve and engages with the driven gears of all gears to realize gear shifting. In the process of frequent gear shifting, the tooth end faces of the meshing gears are easily ground into conical surfaces, which reduces their meshing performance and leads to "tripping and stopping".
2. The performance of the self-locking mechanism decreases. In order to prevent the transmission from "tripping and stopping", this excavator is equipped with steel balls and springs with self-locking function in the box cover hole above the shift forks of the second, third, fourth and fifth gears of the transmission and in the shift forks of the first and reverse gears. When the elasticity of the spring, which plays the role of positioning and self-locking, weakens or breaks, the self-locking performance of the self-locking mechanism will decline until it disappears, resulting in the "trip stop" of the transmission. At the same time, if the positioning steel ball or the groove on the shift fork shaft is worn, it will also cause the transmission to "jump".
3. The gear shifting device is not properly adjusted. The transmission of this excavator uses a manipulator to shift gears manually. If the shift lever, vertical shaft, horizontal shaft and vertical fixing screw are loose, the transmission will also trip.
4. Sudden change of external load Due to the working nature of the excavator and its own design reasons, the sudden change of external load will also cause its transmission to "trip and stop". When the road surface is uneven, the machine runs downhill or the driving route is incorrect, and the external load changes suddenly, the sudden change of the load will act on the gear meshing gear of the transmission through the wheel and the transmission shaft, so that the gear meshing gear will be disengaged due to the axial thrust, resulting in the "jump stop" of the transmission.
Taboo of excavator maintenance method
1, avoid smearing butter.
Grease the cylinder gasket.
Butter is a commonly used grease in the repair of construction machinery, which can play the role of lubrication and sealing. Therefore, some repairmen will coat the cylinder gasket with butter when installing it, thinking that this will increase the sealing performance of the diesel engine.
As everyone knows, this has affected the working performance of diesel engines.
Cylinder gasket is the most important seal between cylinder block and cylinder head of diesel engine. It can not only seal the high-temperature and high-pressure gas generated in the cylinder, but also seal the cylinder head and the cooling water and lubricating oil in the cylinder.
Therefore, when disassembling the cylinder gasket, special attention should be paid to its sealing quality. If the cylinder gasket is coated with butter during installation, part of the butter will be squeezed into the water channel and oil channel of the cylinder when the bolts of the cylinder head are tightened. When the cylinder is working, due to the influence of high temperature, part of the butter left between the cylinder pads will flow into the cylinder for combustion, and the other part will remain on the joint surface of the cylinder block and the cylinder head, resulting in a gap between the cylinder pads, the cylinder head and the plane of the cylinder block. High temperature and high pressure gas can easily impact the cylinder gasket from here, damage the cylinder gasket and cause air leakage.
In addition, if the butter is stored at high temperature for a long time, it will also produce carbon deposition, which will lead to premature aging and deterioration of the cylinder gasket. Therefore, do not grease the cylinder gasket when installing it.
2. Avoid installing new cylinder liners and pistons under mismatched conditions.
When replacing the cylinder liner and piston, it is considered that the new cylinder liner and piston are standard parts, which can be interchanged and can be used after installation.
In fact, the dimensions of cylinder liner and piston have a certain tolerance range. If the largest cylinder liner is equipped with the smallest piston, the fit clearance will be too large, resulting in weak compression and difficult starting.
Therefore, when changing clothes, it is necessary to check the size grouping codes of standard cylinder liners and pistons, and the used cylinder liners and pistons must make the size grouping codes of standard pistons the same as those of standard cylinder liners. Only in this way can we ensure that there is a standard fit gap between them.
In addition, when each cylinder is equipped with the same cylinder liner and piston, it is also necessary to check the cylinder plug clearance before installation. In order to ensure the assembly standard, a test should be carried out before installation to prevent the installation of fake and shoddy products.
3. Do not check the plunger stroke margin.
In the irony test of plunger fuel injection pump, many maintenance personnel do not pay attention to check the stroke margin of plunger.
The so-called plunger stroke margin refers to the amount that the plunger can continue to move upward after being pushed to the top dead center by the cam on the camshaft. After adjusting the start time of oil supply, it is necessary to check the stroke margin, because the stroke margin of plunger is related to the wear of plunger and sleeve.
After the plunger and the sleeve are worn, the plunger must move upward for a period of time to start oil supply, thus delaying the start time of oil supply. When the adjusting bolt is unscrewed or a thicker adjusting pad or washer is used, the lowest position of the plunger moves up, which reduces the stroke margin of the plunger.
Therefore, when maintaining and debugging the fuel injection pump, we should first check the travel allowance to determine whether the fuel injection pump is still allowed to be adjusted.
During inspection, according to the different structures of the fuel injection pump, the following methods should be adopted:
A. Turn the camshaft, push the plunger to the top dead center, remove the oil outlet valve and valve seat, and measure with a depth vernier.
B after the plunger is pushed to the top dead center, pry up the spring seat of the plunger spring with a screwdriver to make the plunger rise to the highest point. Then insert a thickness gauge between the lower plane of the plunger and the tappet adjusting bolt for measurement. The standard stroke margin of plunger is about1.5mm, and the ultimate stroke margin after wear should not be less than 0.5mm. ..
4. Avoid inaccurate measurement of cylinder clearance.
When measuring the cylinder clearance, the piston skirt cannot be measured in the direction perpendicular to the piston pin hole, but only in other directions.
The structure of aluminum alloy piston is characterized by a cone with a small top and a large bottom, and the skirt section is oval, so the cylinder gap along the circumferential direction is not equal.
When measuring, the clearance along the long axis of the ellipse shall prevail, that is, the clearance between the piston skirt and the piston pin hole shall be measured.
This measurement is more convenient and accurate, and the piston skirt is greatly worn by the side pressure in the direction perpendicular to the piston pin hole during reciprocating motion.
Therefore, when measuring the cylinder clearance, the piston skirt should be measured in the direction perpendicular to the piston pin hole.
5, avoid piston open flame heating
Because the piston and the piston pin are interference fit, the piston should be heated and expanded first when installing the piston pin. At this time, some maintenance personnel will directly heat the piston on an open flame, which is very wrong, because the thickness of each part of the piston is uneven, and the degree of thermal expansion and contraction will be different. Heating with an open flame will make the piston heat unevenly and easily cause deformation; Carbon ash will adhere to the piston surface, reducing the service life of the piston.
If the piston cools naturally after reaching a certain temperature, it will destroy its metallographic structure, greatly reduce its wear resistance and shorten its service life. When installing the piston pin, the piston can be heated evenly in hot oil to make it expand slowly, and it must not be heated directly with naked flame.
Excavator maintenance knowledge
1, fuel management
Choose different brands of diesel oil according to different ambient temperatures; Diesel oil cannot be mixed with impurities, lime soil and water, otherwise it will make the fuel pump wear prematurely; The high content of paraffin and sulfur in inferior fuel will damage the engine; After daily operation, the oil tank should be filled with oil to prevent water droplets from forming on the inner wall of the oil tank; Open the drain valve at the bottom of the oil tank to drain water before daily operation; After the engine runs out of fuel or the filter element is replaced, the air in the road must be exhausted. The lowest ambient temperature is 0℃-10℃ -20℃ -30℃. The diesel brand is 0#-10# -20# -35#.
2, other oil management
Other oils include engine oil, hydraulic oil and gear oil; Different brands and grades of oils cannot be mixed; Different kinds of excavator oil have different chemical or physical additives in the production process; To ensure the cleanliness of the oil, to prevent the mixing of water, dust, particles and other impurities; Select the oil label according to the ambient temperature and use. When the ambient temperature is high, the engine oil with high viscosity should be selected; when the ambient temperature is low, the engine oil with low viscosity should be selected; The viscosity of gear oil is relatively large to adapt to large transmission load, and the viscosity of hydraulic oil is relatively small to reduce the flow resistance of liquid. Table 2 External temperature of excavator oil tank℃ Oil type replacement cycle h Replacement amount l Oil pan-35-20 CD SAE 5w-30 250 24-20-10 CD SAE10w-20-40 CD SAE10w-30-1 5-50 CD SAE 6 5438+05W-40 0 CD SAE 30 slewing mechanism box-20-40CD SAE 30W-30CD SAE15W-40 main reducer CD SAE90 1000 5.4
3. Lubricating oil management
The use of lubricating oil and butter can reduce the wear of moving surfaces and prevent noise. When storing grease, dust, sand, water and other impurities should not be mixed; It is recommended to choose lithium-based grease G2-L 1, which has good wear resistance and is suitable for heavy load conditions. When filling, try to squeeze out all the old oil and wipe it clean to prevent sand sticking.
4. Maintenance of filter element
The function of the filter element is to filter impurities in the oil circuit or gas circuit to prevent impurities from invading the system and causing failures; Various filter elements should be replaced regularly according to the requirements of the operation and maintenance manual; When replacing the filter element, check whether the old filter element is attached with metal, and diagnose and take improvement measures in time if metal particles are found; Use pure filter elements that meet the requirements of the machine. The poor filtration ability of fake and inferior filter elements, and the quality and material of filter layer do not meet the requirements, which will seriously affect the normal use of the machine.
5. Contents of regular maintenance
① Replace the fuel filter and additional fuel filter after the new machine works for 250 hours; Check the clearance of the engine valve.
② Daily maintenance; Check, clean or replace the air filter element; Clean the inside of the cooling system; Check and tighten the track shoe bolts; Check and adjust the back tension of the track; Check the air inlet heater; Replace the bucket teeth; Adjust the bucket clearance; Check the liquid level of the front window cleaning solution; Check and adjust the air conditioner; Clean the floor of the cab; Replace crusher filter element option. When cleaning the inside of the cooling system, after the engine is fully cooled, slowly loosen the filler cap, release the internal pressure of the water tank, and then drain the water; Don't clean the engine when it is working, the high-speed rotating fan will cause danger; When cleaning or replacing coolant, the machine should be parked on a level ground.
③ Check items before starting the engine. Check the coolant level and add water; Check the oil level and add oil; Check the fuel level and refuel; Check the hydraulic oil level and add hydraulic oil; Check whether the air filter element is blocked; Check the wires; Check whether the horn is normal; Check the lubrication of the bucket; Check the water and sediment in the oil-water separator.
④ Every 100 maintenance items. Boom cylinder head pin shaft; Boom pin; Rod end of boom cylinder; Pin shaft of bucket cylinder head; Connecting pin of boom and bucket arm; The cylinder rod end of the stick cylinder; Bucket cylinder head pin shaft; Half-bar connecting rod connecting pin; Bucket rod and rod end of bucket cylinder; Bucket cylinder head pin shaft; Connecting pin of connecting rod; Check the oil level and oil in the slewing mechanism box; Drain water and sediment from the fuel tank.
⑤ Maintenance items Check the oil level in the main reducer box every 250 hours and add gear oil; Check the battery electrolyte; Change the oil in the engine oil pan and engine filter; Lubricate the slewing bearing at 2 places; Check the tension of fan belt, check the tension of air conditioner compressor belt and adjust it.
⑥ Maintenance items every 500 hours. At the same time every 100 and 250H maintenance projects; Replace the fuel filter element; Check the height of rotating pinion grease and add grease; Check and clean radiator fins, oil cooler fins and cold sensor fins; Replace the hydraulic oil filter element; Replace the oil in the main reducer box only at 500 hours for the first time, and then at 1000 hours; Clean the air filter inside and outside the air conditioning system; Replace the hydraulic oil drain element.
⑦ Maintenance items every 1000h. At the same time, carry out maintenance projects every 100, 250 and 500h; Replace the oil in the slewing mechanism box; Check the oil level of the shock absorber housing; Check all fasteners of turbocharger; Check the clearance of turbocharger rotor; Inspection and replacement of generator belt tension; Replace the anti-corrosion filter element; Change the oil in the final drive box.
⑧ Maintenance items every 2000 hours. 1. Complete the maintenance project every 100, 250, 500 and 1000h; Clean the filter screen of the hydraulic oil tank; Clean and check the turbocharger; Check the generator and start the motor; Check the engine valve clearance and adjust it; Check shock absorber.
Pet-name ruby above 4000 h maintenance. Increase the inspection of the water pump every 4000 hours; Add the item of changing hydraulic oil every 5000 hours.
Attending long-term storage. When the machine is stored for a long time, the working device should be placed on the ground to prevent the piston rod of the hydraulic cylinder from rusting; The whole machine is cleaned, dried and stored in an indoor dry environment; If it can only be stored outdoors due to conditions, the machine should be parked on a well-drained cement floor; Before storage, fill the oil tank, lubricate all parts, replace hydraulic oil and engine oil, coat a thin layer of butter on the exposed metal surface of the piston rod of the hydraulic cylinder, and remove the negative terminal of the battery, or remove the battery for separate storage; According to the lowest ambient temperature, an appropriate proportion of antifreeze is added to the cooling water; Start the engine once a month, operate the machine to lubricate the moving parts and charge the battery at the same time; Turn on the air conditioner for refrigeration for 5- 10min.
Articles related to maintenance methods and steps of excavators;
★ Maintenance methods and taboos of excavators
★ Excavator maintenance knowledge
★ Excavator maintenance
★ Maintenance method of Komatsu excavator
★ Technical Paper on Excavator Maintenance (2)
★ Maintenance method of Komatsu excavator
★ Maintenance knowledge of Komatsu excavator
★ What is the common maintenance method of Komatsu excavator?
★ What are the maintenance methods of Komatsu excavator?