Knowledge of hydraulic maintenance of excavators​

It is essential to open the excavator because of the daily maintenance and fault maintenance problems. ​Before, I learned that many excavator masters do not know how to solve some common faults. In this paper, I sorted out some questions and answers about excavator maintenance, hoping to solve the problems for the teachers:

1, grinding gear face to pay attention to what?

Gear pump gear wear, to use high precision grinding machine, to find a strong sense of responsibility master operation. For example, the grinding table should be absolutely clean and no dust should be allowed on the platform. Because the table is slightly unclean, it will make the ground plane and the vertical line of the bearing hole offset.

2. What should we pay attention to when assembling gear pumps?

The wear of the pump shell will be more in the oil inlet cavity. If the pump shell is symmetric, it can be turned 180. To use again. For passive gear, the two ends can not be replaced, when removed to make a mark. Because the gear will be worn on one side. The active teeth are 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 over the passive teeth. ​When pump assembly is completed, add a little lubricating oil before the hand to slightly rotate, feel smooth.

3. Whether the bearing on the end face should be replaced at the same time during assembly?

Be sure to replace them at the same time. Because of the wear of the pump end face, the main bearing clearance is too large, so that the gear in the rotation of the swing is caused by.

4, after checking the damping hole is not blocked, why can't the relief valve pressure be adjusted?

Most of this situation is due to the popper valve and seat closed loosely, so that the C chamber oil pressure can not be established.

5, how to know the ground gear plane and bearing hole perpendicularity has changed?

​can only be found in the assembly of gear pump, because the end clearance is very small, generally about 0.05mm. If the end face and bearing hole perpendicularity changes, the pump assembly after the gear shaft will not move. If the locking screw is a little loose, but still turn not smoothly, and then disassemble the gear pump, end face and scratch marks. This is the end plane and the bearing hole is not vertical.

Knowledge of hydraulic maintenance of excavators​

6, one side of the track can only go forward but not backward?

It is caused by the jammed overflow spool in the walking motor. In order to protect the safety of the system, two overload relief valves are set in the system. If one of them is stuck in the overflow position, the system pressure will be lost.

7, one side of the track is slow, but if you do a rotary action at the same time, the track can get up faster. Why?

It's a failure that happens in a lot of backhoes. This is because of insufficient flow to the walking motor plunger pump. When the excavator does another action at the same time, it is equal to adding another piston pump flow. The flow of the two pumps will conflict in the Komatsu 200-2 excavator control valve, and the Komatsu 200-3 to PC200-6 excavator will confluence on the linear running valve.

Insufficient flow of the plunger pump is not necessarily damaged, most of which is caused by the flow control valve not adjusted well. You can refer to the detailed instructions in the heavy equipment manuals.​

8, pull the excavator walking control handle, feel very heavy (almost pull) why?

Traveling distribution valves are different from other distribution valves. The walking distribution valve of most machines is not hydraulically controlled, but is pulled directly by hand through a mechanical tie rod. As the old machines, or distribution of slide valve has wear and tear, makes walking fitting clearance of slide valve and the hole bigger, high pressure oil from the oil duct through the slide valve clearance leakage to one end of the spring, spring has spring cover cover tightly, make the enclosure formed high pressure, cause the distributing valve to have a spring side shift, joystick is heavy in the other direction (lighter).

9. When the walking lever of the two crawlers is operated at the same time to make the excavator start, the engine speed will drop in an instant, or even stall, is the reason?

This failure is quite common. This is mainly because the piston pump variable mechanism has a problem. When the machine is idling, the piston pump still has a large flow rate.

10, the walking oil motor has just been repaired, the track goes faster when the small throttle, but it will not go when the big throttle, what is the remedy?

This is because the maintenance of grinding over the plate and the grinding amount is too much, so that the plate and cylinder plane compression force is not enough. Small throttle when the oil pressure is small, between the plane and the plane is not easy to leak; ​the oil pressure increases when the throttle is high, resulting in overflow between planes, resulting in the track can not move when the throttle is high. This can be remedied by adding spacers to the spring or, if it is a butterfly spring, an extra butterfly spring.

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