Fault phenomenon
When a Hitachi Excavator is working, the right side is weak; it is obvious to the right when walking: When turning to the right, the engine must be run at high speed, and the turns is very slow.
2. Check if the cause of the failure
Check the power transmission order according to the excavator to check the following:
(1) Check hydraulic pump
The motor is supplied by the hydraulic pump, which is supplied to the bucket cylinder, which is ok, which can determine if the bucket cylinder is working properly.
(2) Check the control valve
Symptoms of control valve failure generally: walking valve stem push or smaller stroke; the fit gap between the valve stem and the valve hole is large, and there is a leak; the safety valve pressure is lowered. The above faults will cause the right to travel weakness.
After the examination, the left and right walking operation valve valve stem is the same, indicating that the valve stem operation is no problem, but there is no leakage internally, whether the pressure value of the safety valve is lowered, and it is difficult to determine. Its verification method is to interchange the left and right tubes, but some tubes are difficult to remove, so the control valve has trouble or dosing, and do not do disassembly check.
(3) Check the rotary joint
The hydraulic oil passes from the upper portion of the excavator to the lower travel drive, and must be rotated, if a leak is generated inside the rotary joint, there is a certain amount of high pressure oil to return to the oil pipe, which will also cause the walking weakness, but there is no leakage in the interior. It is difficult to judge in the case, so the part can only be used as a doubt.
(4) Check the walking motor
Since the noise is relatively large when the excavator walks, the listening and touch walking motor and the tubing are not safe.
Use the bucket to support the right travel track, slowly operate the right travel joystick under the idle speed, and you can hear the right line of the motor "Shung" when the drive wheel has not turned, and touches the back oil by hand. The oil stream is oil flow (from the working principle of the motor, when the motor does not work, the oil return pipe should have no oil flow); when the joystick continues to move, the track starts to turn but very slow: the engine accelerates, " The sound of the scuffy is also enhanced. With the same method, there is no such abnormal phenomenon when operating the left line, whereby the right row takes the internal leakage of the motor, the oil return path is in contact, resulting in a decrease in the pressure of the travel motor, so that the motor output torque is reduced. So the right travel motor needs to be inspected.
(5) Check the walking reducer
Since the power transfer between the walking horse reaches the travel drive wheel is normal, there is no sorry, the oil temperature, oil quality and oil level in the reducer is also normal, so it can be excluded that there is a failure of the walking reducer.
According to the above analysis and inspection results, it is determined that the first disintegration of the right travel motor.
3. Troubleshooting
After disintegrating the right travel motor, the distribution sleeve has a falling offset in the high and low pressure oil passage, so that it is connected to the backlap, so that the right travel motor output torque is lowered, walking weakness, which is consistent with the results of the test listening .
Due to the fact that the fixing of the bushing is quite difficult, decide to replace the right travel motor, and the right walk is restored to normal.
