Repair and maintenance of hydraulic excavator excavator is a kind of main machinery in engineering construction. At the same time, it can also be used as a multi-functional operation machine. For example, it can complete a variety of engineering operations such as hoisting, grabbing, ditch cleaning, slope repair, crushing, disassembly, etc. the excavator has become one of the main machinery for engineering construction. What do you know about the hydraulic maintenance knowledge of the excavator?
1. One track can only move forward but not backward?
The overload overflow valve element in the traveling motor and engine is stuck. In order to protect the safety of the system, the traveling motor is equipped with two overload relief valves in the system. If one of the overload relief valves is stuck in the overflow position, the system pressure will be lost.
2. One side of the track moves very slowly, but if you do a turning action at the same time, the track can get up quickly. Why?
This fault occurs on many excavators. This is because the flow to the propel motor plunger pump is insufficient. When the excavator makes another action at the same time, it is equal to the flow of another plunger pump. The flow of the two pumps will be combined in the control valve of Komatsu 200-2 excavator, and the flow of Komatsu 200-3 to pc200-6 excavator will be combined on the straight travel valve.
The insufficient flow of the plunger pump is not necessarily caused by the damage of the pump, but mostly caused by the failure to adjust the flow control valve.
3. When you pull the travel control handle of the excavator, you feel very heavy. Why?
The travel distribution valve is different from other distribution valves. The travel distribution valve of most machines is not hydraulically controlled, but directly pulled by hand through a mechanical pull rod. Because the machine is old, or the distribution spool valve has been worn, the matching clearance between the travel spool valve and the hole becomes larger, and the high-pressure oil will leak from the oil passage through the spool valve clearance to the end with a spring. There is a spring cover outside the spring, which forms a high pressure in the cover. As a result, when the distribution valve wants to move to the side with a spring, the control lever is very heavy (it is light in the other direction).
4. When the excavator is started by operating the walking operating levers of the two crawlers at the same time, the engine speed will drop instantly, or even shut down. What is the reason?
This fault is common. This is mainly because there is a problem with the variable mechanism of the plunger pump. When the machine is idling, the plunger pump still has a large flow.
5. The walking oil motor has just been repaired. When the throttle is low, the crawler moves faster, but when the throttle is high, it will not. What is the remedy?
The walking oil motor has just been repaired. When the throttle is low, the crawler moves faster, but when the throttle is high, it will not. What is the reason and what is the remedy?
This is because the valve plate has been grinded during maintenance and the grinding amount is too much, which makes the pressing force between the valve plate and the cylinder block plane insufficient. When the throttle is small, the oil pressure is small, and it is not easy to leak between the planes; When the throttle is large, the oil pressure increases and overflows between the planes, resulting in the tracks not moving when the throttle is large. The remedy can be to add shims to the spring. If it is a butterfly spring, an additional butterfly spring can be added.
