Answer:
We all know that second-hand excavators often have many failures during work. For some easy failures, here are a few simple and convenient solutions for you:
In the construction operation of hydraulic excavators, according to the load request of the operation, the speed and load (flow and pressure) are inversely proportional, that is, the product of the output pressure and the flow of the pump is a constant, and the output power of the pump is constant or approximately constant; if If the pump control system is malfunctioning, the engine-pump-valve-load can't be optimized and matched in different working conditions, so that the excavator can't work normally.
When dealing with faults, the same goes from simple to complex, analyzing and confirming one by one. Generally start with the electrical system first, then check the hydraulic system, and finally check the mechanical transmission system. When checking the hydraulic system, check the components step by step from the help oil circuit-the control oil circuit-the main oil circuit-to master components.
Slow down
If it is a second-hand excavator that has been used for many years, the speed gradually slows down, which is caused by normal wear and tear. The wear and tear of important components and parts of the whole machine will cause the engine power to decrease and the hydraulic system to leak, so a series of failures are manifested.
Due to the internal energy consumption caused by the leakage, a large amount of heat energy is generated, which makes the entire system rapidly heat up, and the viscosity of hydraulic oil and engine oil decreases, which causes the entire system to generate high temperature. The parts that are out of wear and tear shall be repaired and replaced.
If it is a new excavator that suddenly slows down, it is necessary to simplify and then to check from the following aspects: first check whether the circuit fuse is open or short-circuited; whether the pilot pressure is normal; whether the servo control valve—servo piston is stuck; the distributor merges Failure, etc.; other possibilities are eliminated, and finally the hydraulic pump is disassembled.
Excavator weakness
The whole machine is unable to be divided into several aspects. One is that the engine speeds down sharply when the external load is large, which is expressed in the following two aspects:
1. First check to activate flexibility as mentioned above;
2. Check whether the hydraulic displacement complies with the constant power output. That is, adjust the angle of the swash plate to reduce the displacement without affecting the speed.
The second is that the engine does not slow down when the load is heavy, and the system speed is normal; this requires the adjustment of the system pressure. Because the hydraulic components and hydraulic systems used by various manufacturers are different, the pressure of each hydraulic cylinder is different, as long as it is specified by the manufacturer. Standard debugging is fine. In addition, if the pressure of the regulating relief valve cannot be adjusted and the relief valve is in good condition, it is necessary to check the adjustment system of the hydraulic pump, and even the cylinder block, valve plate, plunger and other parts of the hydraulic pump.
Summarize
Common failures of general excavators are expressed in the above aspects. With the increase in the application of excavators, some of the extensive faults that often appear in construction operations are generally understood by users who have used excavators for more than one or two years; for example, if the excavator is walking off-track, the user can immediately realize: walking The distribution oil seal (also known as the central rotary joint oil seal) is broken; the flow rates of the two hydraulic pumps are different; there is a problem with the moving motor. The hydraulic cylinder drains quickly: you can immediately realize that the safety relief valve is not tightly closed, or the cylinder oil seal is severely damaged, etc.
