The traveling fault of excavator may be one side fault or both sides. The causes of this fault are generally as follows:
1. The central swivel has internal leakage and oil leakage
The central swivel joint of the excavator is an important hub connecting the hydraulic circuit of the upper vehicle body to the chassis to ensure the smooth hydraulic circuit of the traveling system during the rotation of the excavator. It is composed of an internal column and an external shell. The internal column is cast with an annular groove oil passage, and each oil passage has an opening connected to the lower oil outlet. At the same time, between the column of the central swivel joint and the shell Each adjacent oil passage is sealed by a sealing rubber ring to ensure that the hydraulic oil of different circuits does not interfere with each other when the central swivel cylinder moves relative to the shell.
When the sealing effect of the central rotary joint is poor, internal leakage or oil leakage will occur. The hydraulic oil driving the hydraulic motor cannot fully reach the hydraulic motor. Part of the hydraulic oil returns to the oil tank through other circuits, resulting in pressure loss in the hydraulic circuit and powerlessness of the hydraulic motor.
2. Internal leakage fault of traveling motor
In the previous article, it was mentioned that the walking system is composed of walking balance valve, walking safety valve, walking speed switching valve, walking speed switching oil cylinder, walking brake oil cylinder, throttle valve and walking motor. When an internal leakage occurs in a valve group, it will cause the pressure loss of the hydraulic circuit of the walking system and lead to walking failure.
3. The hydraulic pump pressure is insufficient and the pump control circuit is faulty
Insufficient pressure of the main hydraulic pump is also an important cause of travel failure. The main causes of insufficient pressure of the hydraulic pump are internal leakage of the pump and failure of the pump control system, resulting in pressure loss.
4. Internal leakage of main control valve
The main control valve is a multi spool valve group. When the working time is long or the hydraulic oil contains impurities, the spool will be worn. When the spool of the hydraulic circuit of the control travel system is worn too much, internal leakage will occur, resulting in pressure loss of the hydraulic circuit and travel failure.
5. The secondary pressure oil pressure of the pilot system is insufficient
The secondary pressure oil of the pilot system is output by the proportional control valve. When the travel operation valve in the excavator cab leaks or sticks, it will lead to insufficient pressure of the pilot secondary pressure oil, unable to push the valve core of the main control valve in place, resulting in reduced flow of the hydraulic circuit of the travel system.
6. High and low speed conversion fault of traveling system
Generally, the traveling system of excavator has high-speed gear and low-speed gear. When switching to high-speed gear, the hydraulic circuit flow of traveling system is large, the pressure is low, the hydraulic motor speed is fast, but the torque is low. When switching to low gear, the hydraulic circuit flow of the traveling system is small, the pressure is high, the speed of the hydraulic motor is slow, but the torque is high. When the traveling system cannot be switched to the low gear, the traveling system of the excavator will have the symptom of weakness.
