Excavator Running Deviation Fault Reason

What is excavator deviation:

Excavator deviation, also known as excavator walking deviation, generally refers to the deviation of the crawler track to the left or right, which seriously affects work efficiency. Below are the reasons and repair methods for excavator running deviation collected by Guoxiang Excavator Maintenance Network.

Classification of excavator running deviation:

  1. Track slackness causing deviation
  2. Hydraulic system causing deviation

Causes and repair methods for excavator running deviation:

Dirt entering the balance valve in one side's parking brake oil circuit of the machine When the machine is walking, if dirt blocks the small holes of the balance valve, causing the parking brake to not be released, it results in walking deviation. Because when the machine is walking, if the pressure oil cannot enter the spring chamber of the balance valve to push the balance valve core to move through the small holes of the balance valve, the pressure oil cannot enter the hydraulic system through the groove on the balance valve, causing the parking brake force cannot be released, and as a result, the walking motor cannot rotate, resulting in walking deviation. The method to eliminate this is to clean the balance valve; avoid the entry of dirt during disassembly and assembly; regularly replace the qualified hydraulic oil and filter element.

Damaged sealing ring of the center rotary joint The center rotary joint consists of a housing and a core shaft, with the housing installed on the upper body and the core shaft installed on the lower body. The core shaft has a ring-shaped groove equal to the number of oil pipes. The hydraulic oil from the housing flows through these grooves from the vertical holes on the core shaft to the walking motor, so even if the housing rotates continuously with the upper body, the grooves on the core shaft can remain unobstructed with the oil ports on the housing. So that hydraulic oil can freely enter and exit. If the filter element of the hydraulic oil is not replaced in time, it can cause the bypass valve on the filter element to open, and the impurities in the oil directly enter the sliding surface of the center rotary joint without being filtered, causing damage to the sealing ring on it. As a result of the pressure oil leakage on one side of the machine during walking, the speed of the two walking motors is different, resulting in the excavator running deviation. The method to eliminate this is to replace the center rotary joint oil seal and replace the hydraulic oil and filter element.

Debris blocking the small holes of the balance valve of the final drive system, causing the parking brake force to not be released When the machine is walking, if the pressure oil cannot push the balance valve core to move through the small holes on the balance valve, the pressure oil cannot relieve the parking brake force through the grooves on the balance valve, causing the walking motor to not rotate normally, resulting in the excavator running deviation. The method to eliminate this is to clean the balance valve; avoid the entry of dirt during disassembly and assembly.

Oil leakage of the safety valve of the walking motor If the safety valve leaks oil, it will cause the pressure in the system to be too low, resulting in insufficient speed of the walking motor, resulting in running deviation. The method to eliminate this is to replace the damaged walking motor safety valve; for judgment, the left and right walking motor safety valves can be swapped to see if the deviation occurs during reverse walking.

Output pressure (pressure control) of the walking proportion valve on one side of the machine is too low This proportion valve can output corresponding control oil pressure according to the length of the stroke controlled by the operating handle, so that the main control valve has a corresponding amount of movement, thereby controlling the speed of the working device. If the filter element of the oil is not replaced on time, the filter element may be blocked, causing the bypass valve of the filter element to open. The dirty hydraulic oil directly enters the circuit of the proportion valve without filtration, causing the spool in the valve to jam, and the control oil cannot flow to the rotation main control valve through the walking proportion valve on one side of the machine, causing running deviation. When checking, check the pressure of the walking proportion valve (3.3MPa). The method to eliminate this is to clean the valve body and the pre-oil circuit, and replace the hydraulic oil and filter element.

Damage to the walking suction valve on one side of the machine The suction valve is installed on the hydraulic cylinder and motor of the working device. Its function is to unload the abnormal high pressure (usually below 36.5MPa) in the cylinder or motor when the cylinder or motor is subjected to a huge external impact force to protect the relevant oil pipes and cylinder from damage. If the walking suction valve is damaged, the spring inside the valve becomes soft or broken, the oil pressure in the walking main valve will decrease, the driving force of the walking motor will be insufficient, and the walking deviation will occur. The method to eliminate this is to repair or replace the suction valve.

Malfunction of the walking main valve spool on one side of the machine If the spring inside the walking main valve becomes soft or broken, or the spool is stuck, it may cause the oil pressure to decrease, resulting in walking deviation. When checking, measure the pressure of the walking main valve oil circuit, and the normal value should be 32.5MPa. If the walking main valve is damaged, it needs to be replaced or repaired. Therefore, when a walking deviation fault occurs, the first thing to consider is whether the walking main valve is damaged to avoid taking the wrong path.

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