TEN Tips For Excavator Maintenance

- Nov 29, 2019-

1.What should I pay attention to when grinding the end faces of gears?

After the gear of the gear pump is worn, it is necessary to use a high-precision grinder for grinding, and a responsible master must be operated. For example, the work table of the grinder must be absolutely clean, and no dust is allowed on the platform. Because the table is slightly unclean, the ground plane will be offset from the vertical line of the bearing hole.

2.What should I pay attention to when assembling a gear pump?

Pump casing wear will be a little more in the oil inlet chamber. If the pump casing is symmetrical, it can be turned 180. reuse. For passive gears, the two ends cannot be exchanged, and a mark must be used when removing. Because the gear will wear on one side. The driving tooth is integrated with the rotating shaft and cannot be reversed; turning the passive tooth can change the contact point of the meshing line of the two gears. After the pump is assembled, you need to add a little lubricating oil and then slightly rotate it by hand to feel smooth.

3. Should the bearings on the end face be replaced at the same time during assembly?

Be sure to replace them at the same time. Due to the wear of the pump end face, the bearing clearance is too large, which causes the gear to sway during rotation.

4. After checking that the damping hole is not blocked, why can't the pressure of the safety valve be adjusted?

Most of this situation is due to the tight closing of the poppet valve and the valve seat, so that the oil pressure in the C cavity cannot be established.

5. How do I know that the perpendicularity of the ground plane of the gear and the bearing hole has changed?

It can only be found when assembling a gear pump, because the clearance at the end face is very small, generally around 0.05mm. If the verticality of 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 turn smoothly, the gear pump is disassembled and inspected, and there are scratches on the end surface. This is because the end plane is not perpendicular to the bearing hole.

6. One side of the track can only move forward but not backward?

It is caused by the overload relief valve core in the walking motor being stuck. To protect the safety of the system, the travel motor is equipped with two overload relief valves in the system. If one of the overload relief valve spools is stuck in the overflow position, the system pressure will be lost.

7. The crawler walks very slowly on one side, but if you perform a turning movement at the same time, the crawler can get up fast. Why?

This failure occurs on many backhoes. This is because the flow rate to the travel motor plunger pump is insufficient. When the excavator performs another action at the same time, it is equivalent to adding the flow of a plunger pump. The insufficient flow of the plunger pump does not necessarily mean that the pump is damaged, most of which are caused by the flow control valve not being properly adjusted.

8. Why do I feel heavy (almost unable to move) when I pull the excavator's walking control handle?

The travel distribution valve is different from other distribution valves. The travel distribution valve of most machines is not hydraulically controlled, but directly pulled manually by a mechanical drawbar. Because the machine is old or the distribution slide valve has been worn, the clearance between the walking slide valve and the hole becomes larger, and high-pressure oil will leak from the oil passage through the slide valve gap to the end with the spring. Therefore, when the high pressure is formed inside the cover, which causes the distribution valve to be shifted to the side with a spring, the control lever is very heavy (lighter in the other direction).

9. Simultaneously operating two crawler walking joysticks to start the excavator, the engine speed will drop instantly, or even stop, why?

This fault is more common. This is mainly a problem with the variable displacement mechanism of the plunger pump. When the machine is idling, the plunger pump still has a lot of flow.

10. The running oil motor has just been repaired. The crawler will go faster when the throttle is small, but it will not go when the throttle is large. What are the remedies?

This is because the distribution plate is ground and the grinding amount is too large during maintenance, so that the pressing force between the distribution plate and the plane of the cylinder is insufficient. When the throttle is small, the oil pressure is small, and it is difficult to cause leakage between the plane. When the throttle is large, the oil pressure is increased, which causes overflow between the planes. As a result, the track cannot be moved when the throttle is large. The remedy is to add a gasket to the spring. If it is a butterfly spring, you can add an extra piece of butterfly spring.