Failure phenomenon:
Imported Komatsu 200-8 hydraulic excavator with working hours of 7,800 hours, original paint of the whole machine, original engine, original hydraulic shut-off valve, original hydraulic pump, original total travel, maintenance of the whole machine is quite good, and no guns were fired. There is no overhaul. Recently, during the construction of the machine, the brake failure occurred when the right-turning action was performed, and the machine was braking when the left-turning action was performed, but it reversed an angle of 15-20 degrees after braking.
Cause of failure:
1 Internal malfunction of swing motor
2 Pilot release brake oil circuit failure
3 Rotary brake solenoid valve control circuit failure
Maintenance steps:
1.Removing and inspecting the rotary motor safety valve component, it was found that the right check valve body (706-75-74550) was radially broken from the middle, and the small end flow could not be taken out on site in the valve body, and the spring (706-75-74550) There is obvious deformation;
2.Other oil circuits and electrical control systems are normal.
Failure check conclusion:
Defective turning motor parts.
Repair method:
Replace the swing motor assembly.
