Elimination of running deviation of hydraulic excavator

A Korean Daewoo DH220LC-V hydraulic excavator, about 5000h after work, appeared in advance or after retrogression, are left to the right deviation of the fault.

Analysis shows that the main reasons for the deviation of the main hydraulic pump, pump regulator, the main control valve on the spool, the center of the joint and the motor and other hydraulic components, as well as the pilot pressure, track tension and so on. Thus, the following checks were carried out:

First, check whether the tensioning of the tracks on both sides is consistent. On both sides of the track were propped up, check the horizontal line at the maximum amount of sinking crawler chassis and the distance between the results are within the scope of the standard (general road 320~340mm, muddy road 340~380mm, gravel, snow 380mm).

Second, check whether the pilot pressure of the front and rear pumps is consistent from the instrument panel. If inconsistent, then adjust the front and back pump lead pressure, idle speed (engine) is 3.2MPa. 4MPa at high speed.

Then, the high-pressure tubing will walk from the center to the motor swap joint test machine if the fault phenomenon has changed, you can rule out the right running motor fault, otherwise there is fault right walking motor, walking motor should be opened for inspection, to pinpoint the cause of failure.

The main control valve and the center joint 4 tube in left and right walking oil exchange, when the test machine if the fault phenomenon has changed, may be excluded from the center joint failure, or as the center joint failure, and failure to identify the reasons apart.

Check the left and right control valve spool, and found that the valve core in the valve movement is flexible, and no damage, it can be ruled out the control valve failure.

When the two main pump regulator is exchanged, it is found that the fault of the running deviation is changed, so that the fault can be judged on the regulator, otherwise the fault should be on the hydraulic main pump.

Through the above inspection, it is found that the fault should be on the pump regulator. Open the regulator, it was found that the O shape on the valve core sealing ring has been aging damage, resulting in valve movement is not flexible, unable to carry out normal adjustment of the swashplate angle, so that after the pump displacement becomes small, slow walking speed, the machine running right deviation.