When the excavator is resting, it is necessary to check the excavator and repair it if there is any problem. This article will answer some common questions during normal maintenance for reference only.
1. What should we pay attention to when grinding the gear end face?
After the gear of the gear pump is worn, it is necessary to use a high-precision grinder for grinding, and find a master with a strong sense of responsibility for operation. For example, the grinding table should be absolutely clean and no dust is allowed on the platform. Because the workbench is slightly unclean, the ground plane will deviate from the vertical line of the bearing hole.
2. What should we pay attention to when assembling the gear pump?
The wear of the pump casing will be more in the oil inlet chamber. If the pump casing is symmetrical, it can be turned over 180 °. Reuse. For the driven gear, the two ends cannot be exchanged, and mark it when removing it. Because the gear will wear on one side. The driving gear is integrated with the rotating shaft and cannot be turned over; The contact point of the meshing line of the two gears can be changed by turning the passive teeth over. After the pump is assembled, add a little lubricating oil before rotating slightly by hand, and the feel should be smooth.
3. Should the bearing on the end face be replaced at the same time during assembly?
Be sure to replace it at the same time. The wear of the pump end face is mainly caused by the swing of the gear during rotation due to the large bearing clearance.
4. After inspection, the damping hole is not blocked. Why can't the pressure of the safety valve be adjusted?
Most of this is because the cone valve and valve seat are not tightly closed, so that the oil pressure in chamber C can not be established.
5. How to know that the perpendicularity between the ground gear plane and the bearing hole has changed?
It can only be found when assembling the gear pump, because the clearance of the end face is very small, generally about 0.05mm. If the perpendicularity between the end face and the bearing hole changes, the gear shaft cannot move after the pump is assembled. If the locking screw is loosened a little, but still does not rotate smoothly, disassemble and inspect the gear pump, and there are scratches on the end face. This is caused by the fact that the plane of the end face is not perpendicular to the bearing hole.
6. One track can only move forward, not backward?
It is caused by the overload overflow valve core in the traveling motor being 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.
7. One 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 does another action at the same time, it is equal to the flow of another plunger pump. The insufficient flow of the plunger pump is not necessarily due to the damage of the pump, but mostly due to the poor adjustment of the flow control valve.
8. It's very heavy to pull the walking control handle of the excavator. 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 slide valve has been worn, the matching clearance between the travel slide valve and the hole becomes larger, and the high-pressure oil will leak from the oil passage through the slide valve clearance to the end with spring. There is a spring cover outside the spring, which forms high pressure in the cover. As a result, when the distribution valve wants to shift to the side with spring, the control lever is very heavy, but it is very light to the other side.
9. Operate the walking levers of the two crawlers at the same time, so that when the excavator starts, the engine speed will drop in an instant, or even stop. Is it and why?
This fault is common. This is mainly a problem with the variable mechanism of the plunger pump. When the machine is idling, the plunger pump still has a large flow.
10. The walking oil motor has just been repaired. When the throttle is small, the crawler moves faster, but when the throttle is large, it won't go. What is the remedy?
This is because the valve plate has been grinded during maintenance, and the grinding amount is too much, so that the pressing force between the valve plate and the plane of the cylinder block is not enough. When the throttle is small, the oil pressure is small, and it is not easy to leak between planes; When the throttle is high, the oil pressure increases and overflow occurs between the planes, resulting in the crawler not moving when the throttle is high. The remedy can be to add a gasket on the spring. If it is a butterfly spring, an additional butterfly spring can be added.
