During the working period, Hitachi EX90 suddenly had a stick and was unable to walk to the right. Significantly shifted to the right when walking on a flat road. Everything is normal when turning right, but walking on the right is weak; when turning left, the diesel engine must be fast and the turning is very slow.
According to the analysis of the driving force transmission sequence, the right travel motor is interrupted by the hydraulic oil pump, which is likely to cause an accident. In addition to the interruption of the oil supply to the walking drive equipment, this pump is likely to cause accidents, and the bucket cylinder oil supply is interrupted, which is likely to cause accidents. Check that everything is normal during the operation of the bucket cylinder, and the pressure can exceed 26. MPa, so it is clear that there is no problem with the pump.
First, inspect the rotary joint. If there is a leakage inside the rotary joint, a part of the high pressure oil will flow into the return oil pipe, causing walking weakness. Install the hydraulic gauge on the walking inspection port and check that the pressure is all normal, confirming that the rotary joint is also good.
In addition, check the pressure regulating valve. Common faults such as the jamming of the spool of the walking control valve, the short stroke arrangement, the large gap between the spool and the valve hole, and the reduction of valve pressure can all cause the right walking weakness. The system detects that the spool stroke of the left and right walking control valve is the same, indicating that the spool posture is no problem; the valve pressure value is all normal, indicating that the control pressure regulator is good; the oil temperature, oil product and oil volume in the walking speed reduction equipment are also all everything is normal.
Finally, the walking motor is detected. Use the bucket support point to start the right walking cover, and gradually operate the right walking operating handle while the diesel engine is at a speed. When the driving wheel is not rotating, you hear the sound of the right walking motor "hiss, hiss", touch it with your hand Touching the oil pipeline, I feel that there is fluidity in the pipe. When the operating handle is posture again, the cover belt just starts to rotate, but it is very slow. When the diesel engine speeds up, the "hiss, hiss" noise also increases. Use the same method to check that there is no abnormality when walking on the left.
This proves that the internal leakage of the right travel motor causes the fuel inlet and return pipes to communicate, resulting in a reduction in the pressure of the travel motor's fuel inlet hole, which in turn reduces the motor output torque. After the disintegration, it was discovered that a valve bushing fell off from the interval between the high and bottom pressure oil passages of the right walking motor. Because the bushing was difficult to repair, the right travel motor was replaced. After installation and commissioning, the excavator walked right to recover.
