Indispensable for driving an excavator is daily maintenance and troubleshooting. Here are some questions and answers about excavator maintenance, hoping to solve some problems for everyone:

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

　　 This situation is mostly due to the loose closure of the poppet valve and the valve seat, so that the oil pressure in the C cavity cannot be established.

　　 2. What should be paid attention to when grinding gear end faces?

　　 After the gears of the gear pump are worn out, use a high-precision grinder to grind, and find a responsible master for operation. For example, the workbench of the grinder must be absolutely clean and no dust on the platform is allowed. Because the workbench is slightly dirty, the ground plane will be offset from the vertical line of the bearing hole.

　　 3. How do I know that the perpendicularity between the gear plane and the bearing hole has changed? It can only be found when assembling a gear pump, because the gap on the end face is very small, generally around 0.05mm. If the perpendicularity between the end face and the bearing hole is changed, the gear shaft cannot move after the pump is assembled. If the locking screw is loosened a little, but it still does not rotate smoothly, and then disassemble the gear pump, there are scratches on the end surface. This is caused by the end plane being not perpendicular to the bearing hole.

　　 4. What should be paid attention to when assembling the gear pump?

　　 The abrasion of the pump casing will be a bit more in the oil inlet cavity. If the pump casing is symmetrical, it can be turned over 180. reuse. For the passive gear, the two ends cannot be exchanged, and a mark should be made when removing it. Because the gear will wear on one side. The driving tooth is integrated with the rotating shaft and cannot be turned over; turning the passive tooth over can change the contact point of the meshing line of the two gears. After the pump is assembled, it is necessary to add a little lubricating oil before rotating it slightly by hand. The hand feel should be smooth.

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

　　 must be replaced at the same time. Because of the abrasion of the end face of the pump, the main reason is that the bearing clearance is too large, causing the gear to swing during rotation.

　　6. One crawler can only move forward, not backward. What is the reason?

　　 is caused by the jamming of the overload relief spool in the traveling motor. In order to protect the safety of the system, the walking motor has 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. Why is it heavy (almost unable to move) when turning the excavator walking control handle?

　　The walking distribution valve is different from other distribution valves. The walking distribution valve of most machines is not hydraulically controlled, but is directly pulled manually by a mechanical pull rod. Because the machine is old or the distribution slide valve has worn out, the matching gap between the walking slide valve and the hole has become larger. High pressure oil will leak from the oil passage through the slide valve gap to the end with the spring, and the spring cover is tightly covered outside the spring. At the same time, high pressure is formed in the cover, causing the distribution valve to shift to the side with the spring, the control lever is very heavy (the other direction is lighter).

　　 8. When operating the walking joysticks of two crawlers at the same time to start the excavator, the engine speed will drop instantly, or even stall, what is the reason?

　　 This failure is more common. This is mainly a problem with the variable mechanism of the plunger pump. The plunger pump still has a large flow when the machine is idling.

　　9. The walking oil motor has just been repaired, and the track moves faster when the throttle is low, but it won't go when the throttle is high. What is the reason and the remedy?

　　 This is because the valve plate has been ground during maintenance and the amount of grinding is too much, which makes the pressing force between the valve plate and the cylinder block surface insufficient. When the throttle is small, the oil pressure is small, and it is not easy to leak between the plane and the plane; when the oil pressure is increased, the oil pressure between the planes will overflow, which causes the crawler to not move when the throttle is high. The remedy can be to add a washer to the spring, if it is a butterfly spring, you can add an extra butterfly spring.

　　 10. One side of the crawler walks very slowly, but the crawler can get up quickly if you do a rotation at the same time. What is the reason?

　　 This failure occurs on many excavators. This is because the flow rate supplied to the travel motor plunger pump is insufficient. When the excavator does another action at the same time, it is equal to the flow rate of another plunger pump. The flow of the two pumps will merge in the Komatsu 200-2 excavator control valve, and the Komatsu 200-3 to PC200-6 excavators will merge in the straight travel valve. Insufficient flow of the plunger pump is not necessarily caused by the damage of the pump, but mostly because the flow control valve is not adjusted well.