Common faults of excavators
Troubleshoot Pilot System
Therefore, there is no slippage in the latter case of the driving test (1) and the slope stop test (2). Test the pilot pressure, its value is 4.1MPa, which is normal. Therefore, the possibility of malfunction of the pilot system can be ruled out. Then, verify whether the electronic control system is malfunctioning. The method of judging this failure is relatively simple, because the system has a manual backup switch. When the main controller or monitor of the excavator has a problem, move the backup switch to the manual position, so that the machine can continue to work. Operating the machine as described above still turned out to be slow. Therefore, it can be preliminarily considered that the main controller is normal; then, turn the switch back to the automatic position, and then check the three light-emitting diodes on the main controller. When the excavator is repaired, the three diodes are green. The communication line between the controller and the monitor is normal. Caterpillar's excavator monitoring system has a strong self-test and data memory function, so we can understand the status and data of other electronic components through the monitor.
In order to determine whether they are working properly. After entering the password from the monitor. Enter Caterpillar's maintenance mode. First check the status of the switches. The excavator repair results show that the various switches are in the normal position. Then check the rated engine speed and the pressure of the pump when the main safety valve is vented, min and 34.3. MPa, all are normal values; check the pressure change range of the proportional reduction pressure valve. During the normal operation of the excavator maintenance, the monitor shows that the pressure change range of the pressure reducing valve is 3.2 ~ 0.76MPa, that is, the proportional pressure reducing valve. The pressure changes are normal. Then check the actual fault codes of the shield and the previously recorded fault codes. The fault code is not displayed on the monitor. So far, it is certain that the problem is not the electronic control system. Finally, check the hydraulic pump's own adjustment system. The upper and lower pump regulators are separated, and there are problems when passing the test table for left and right unilateral walking, because the possibility of failure of both pump regulators is small. Excavator repair, excavator repair, repair excavator, repair excavator
Let's set it aside first. Look at it from the outside. There are two external control signals for the hydraulic pump regulator: one is from the pressure PN of the central oil passage of the main control valve, one for the upper and lower pumps; the other is the pressure PS from the proportional pressure reducing valve that controls the upper and lower pumps simultaneously . First measure the pressure PN values of the upper and lower pumps respectively. It is obtained that when the main control valve is in the neutral position, the pressure is 4.07 MPa. No matter what happens, the PN drops to 0.35 MPa and the PN value is normal. Measure the PS value again. Although the range of PS value has been viewed through the monitor and the pressure change value is normal, this is not necessarily accurate because there is no pressure sensor on the proportional pressure reducing valve to directly signal the main controller. Input, the pressure value displayed by the monitor is converted by the main controller through the output current signal of the proportional pressure reducing valve through analysis, that is, this pressure value corresponds to the output current of the main controller's proportional pressure reducing valve. . To do this, connect a pressure gauge on the PS pressure side of the pump body.
Before disassembling the engine assembly, power off the entire vehicle and remove the negative terminal of the battery connection cable. 1. Remove the bottom plate under the water tank, and gradually unscrew the water tank cover. (If it is a hot car, you should carefully twist the water tank cover with a damp cloth to release the pressure. The pressure can be fully opened after the pressure is released to prevent hot water.) Remove and store the antifreeze in the water tank. 2. Remove the bottom plate under the engine and drain the oil. 3. Remove the hood cover and the upper cover of the large pump. 4． Remove 5. Remove the four long pawl pad bolts holding the engine. 6. Remove the fan and air-conditioning compressor. 7. Use a screwdriver to remove the upper and lower water pipes of the water tank and the heater air pipe connected to the engine. Excavator maintenance, excavator repair, maintenance excavator, use a screwdriver to remove the fuel pipe inlet pipe and oil return pipe connected to the jet pump. 9. Disconnect the power cord and ground wire connected to the starter. 10. Disconnect the wiring harness that connects the engine harness to the main harness. 11 Prepare a relatively strong steel pipe and fix the main pump with a chain hoist.
Remove the bolts fixing the main pump to the engine. 12. After the above work is completed, use a special spreader to lift the engine out. Lifting should be carried out carefully and smoothly. Pay attention to the presence of components connected to the engine during lifting and unloading. The disassembly (220-v) disassembly of the engine assembly is an important part of engine maintenance. It must be carried out in strict accordance with technical requirements to ensure the quality of maintenance. (1) Appropriate tools and special tools should be used during the disintegration process. Use less hoe to beat and less use crowbar to avoid prying, to reduce unnecessary damage and protect the function of disassembling parts. For rusted parts that cannot be disassembled, you can add rust remover first and then disassemble. (2) Before disassembly, clean the disintegrated part or all the oil and dust of the engine to prevent the engine from being dislodged from disassembling parts, keep the operator's work clothes and hands clean, and improve the maintenance level. (3) In order to ensure the original fit of the engine component assembly and to ensure the smooth assembly after maintenance.
For mating parts, it is necessary to mark the appropriate position; for parts that are prone to error, it can be appropriately marked or labelled. It is best not to mix the components of one engine with other engines for smooth assembly. (4) The relevant assemblies and parts of each cylinder of the engine shall be disassembled and properly stored in order according to the serial number of the cylinder and its assembly relationship, so as to check, repair and replace, and ensure error-free assembly. (5) Parts and assemblies of each engine system should be disassembled and stored in order to facilitate assembly. (6) Mark and record the individual parts that are difficult to identify the assembly position and assembly relationship to facilitate inspection and assembly. Before disassembling the engine assembly, clean the engine's appearance with pressure water, and then fix the engine on the engine turntable with special tools. 1. Remove the engine harness, generator and starter. 2. Use a 17 # wrench to remove the high pressure pipe of the jet pump. Use a screwdriver to remove the two water pipes from the pump to the intercooler.
4. Use a 13 # sleeve to remove the 11 fixing bolts fixing the engine intake manifold, and remove the engine intake manifold. 5. Use a 17 # wrench to remove the oil inlet pipe connected to the engine turbocharger, and a 13 # wrench to remove the turbocharger oil return pipe. 6. Remove the engine exhaust manifold with a 13 # sleeve. 7. Remove the four screws fixing the valve chamber cover with a 17 # sleeve, and remove the valve chamber cover. 8. Remove the valve rocker with 13 # and 12 # sleeves. 9. Use a 17 # sleeve to remove the 26 bolts that fix the cylinder head. 12. The engine is turned over. Remove the oil pan and the oil pump with a 13 # sleeve. 13 Remove the engine crankshaft pulley fixing nut with a 55 # sleeve, and take out the crankshaft pulley with a special tool. 15. Remove the jet pump with a 13 # sleeve. 16. Remove the engine timing gear cover with a 13 # sleeve. 17. Remove the intermediate gear of the timing gear set with a 17 # sleeve.
Analysis of failure reason (Analyse): Because the output oil pressure of the rear pump vibrates violently and the excavator repairs, the rear pump has a problem. At the same time, it is found that the rear pump has metal powder flowing out and yellow copper (chemical formula Cu) powder particles, and the column The plug has a copper sleeve, so the copper sleeve is likely to be twisted, and the failure phenomenon after damage is consistent with the above. Remove the main pump on site, clean the outside, and find one at the construction site. The clean and flat place began to disintegrate the main pump carefully. The disassembly of the main pump confirmed that the plunger in the pump was broken three times, and the rest was not significantly damaged. The plunger should have been replaced, but because there were exactly five newer old plungers of the same model on hand, the five old plungers that were more damaged in the rear pump were replaced, and they were evenly distributed as soon as possible. The installation position (ition) of the plug is to strive for equalizing the force when the main pump rotates. The main pump oil seal and oil return filter have been replaced (function: filtering impurities, etc.).