In the process of excavator construction, whether it is transfer, loading, trenching or slope brushing, each construction operation is closely related to walking action. If the walking action is abnormal, all construction will be affected. Many people don't know how to deal with faults such as one-sided and one-way walking without action. This article will explain how to solve this problem for reference only.
The traveling motor on one side of the excavator can only move forward but not backward, or it can only move backward but not forward, and the traveling on the other side is normal. Other movements of the excavator are normal.
1. Fault cause inspection
1) Firstly, according to the fault phenomenon of the excavator, the overflow pressure and control pressure of the walking are checked through professional testing equipment, and it is found that the pressure is normal.
2) then replace the AB port oil pipe on the fault side, and the trouble remains. Therefore, it is concluded that the fault is inside the travel motor.
3) Next, disassemble the motor and check that the balance valve, overflow valve and parking brake of the motor are normal.
4) Finally, solid colloidal particles were found blocking the oil passage at the orifice at the front end of the oil inlet on the fault side of the balance valve.
2. Principle of causing failure
The pressure oil from the main control valve of the travel motor flows into the motor from the A or B oil port of the motor through the central swivel to drive the motor to rotate. At the same time of oil inlet a or B, open the balance valve and open the parking brake of the traveling motor through the balance valve. Otherwise, even if the pressure oil pressure at the oil inlet a or B is higher, it can only overflow and return oil from the overflow valve without opening rotation, and the motor will not rotate.
When parking, close the forward or backward pressure oil port a or B. because the oil port is closed, the brake oil circuit is closed at the same time, and the braking function is realized. However, due to the inertia of walking, the motor continues to rotate, and the nature of the motor becomes a pump. At this time, the overflow valve works, the return oil pressure increases, open the overflow valve, and the return oil is supplemented to the original oil inlet. Realize the buffer of shutdown and prevent high voltage from damaging the system.
The orifice at the front end of the balance valve is an oil circuit connected in parallel with the A / b oil port. Among the two oil ports, when one has high-pressure oil, the other is low-pressure oil return. After the orifice is connected in parallel with the high-pressure oil port, open the balance valve and open the brake. Therefore, when one side of the orifice is blocked, the travel brake on this side cannot be opened, so the travel brake cannot be driven
3. Solution
1) After cleaning the orifice, restore the oil circuit, test the normal running and eliminate the fault.
2) Judging from the material of solid particles, it may fall off the inner wall of the rubber hose, or it may be the residue of damaged gasket and sealing ring somewhere. Therefore, it is recommended to further check and replace the rubber parts in the walking oil circuit.
