Analysis on the cause of the walking deviation of

2022-08-07
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Cause analysis of excavator traveling deviation

1. When dirt enters the balance valve in the parking brake oil circuit on one side of the machine, if dirt blocks the small hole of the balance valve, the parking brake cannot be released, resulting in traveling deviation. Because when the machine is running, if the pressure oil can not enter the spring chamber of the balance valve through the small hole of the balance valve to push the balance valve core to move, the pressure oil can not enter the hydraulic system through the groove on the balance valve, resulting in the parking brake force can not be released, and the walking motor can not rotate. Therefore, there is a small running deviation with considerable noise. Exclusion method; Clean the balance valve; Avoid dirt when disassembling; Regularly replace the hydraulic oil and filter element that meet the requirements

2. The sealing ring of the central swivel joint is damaged

the central swivel joint is composed of a shell and a mandrel. The shell is installed on the upper vehicle body, and the mandrel is installed on the lower vehicle body. The mandrel is provided with annular grooves equal to the number of oil pipes, and the hydraulic oil from the shell flows from the vertical holes on the mandrel to the traveling motor through these grooves. Therefore, even if the shell rotates continuously with the upper vehicle body, the grooves on the mandrel can remain unblocked with the oil ports on the shell. The hydraulic oil can enter and exit freely. If the filter element of the hydraulic oil is not replaced in time, the bypass valve on the filter element may be opened, and the impurities in the hydraulic oil may directly enter the sliding surface of the central swivel due to unfiltered hydraulic oil, causing damage to the sealing ring on it. When the machine is traveling, the speed of the traveling motors on both sides is different due to the leakage of pressure oil on one side, resulting in the deviation of the machine. Troubleshooting: replace the central swivel oil seal; Replace the hydraulic oil and filter element

3. Dirt blocks the small hole of the balance valve of the final drive system, resulting in the failure to release the parking brake force.

when the machine is traveling, if the pressure oil cannot push the balance valve spool to move through the small hole on the balance valve, the pressure oil cannot release the parking brake force through the groove on the balance valve, resulting in the failure of the travel motor to rotate normally, resulting in the deviation of the excavator. Troubleshooting: clean the balance valve; During disassembly and assembly, dirt must be avoided

4. The safety valve of the travel motor leaks oil

if the safety valve leaks oil, the pressure in the system will be too low, and the speed of the travel motor will be insufficient, resulting in travel deviation. Troubleshooting: replace the damaged travel motor safety valve; When judging, the left and right travel motor safety valves can be exchanged to see whether they deflect during reverse travel

5. The output pressure (pressure control) of the travel proportional valve on the deflection side of the machine is too low

this proportional valve can output the corresponding control oil pressure according to the length of the control stroke of the operating handle, so that the main control valve has the corresponding movement, so as to control the speed of the working device. If the filter element of the oil filter is not replaced on time, the filter element may be blocked, so that the bypass valve of the oil filter of the pan European dealer, which was the first parent of the filter, will be opened, and the dirty hydraulic oil will directly enter the circuit of the proportional valve without filtering, causing the slide valve in the valve to be stuck, and the control oil will not flow to the main rotary control valve through the rotary proportional valve on the deflection side of the machine, resulting in deviation of the travel. During inspection, check the pressure (3.3Mpa) of the travel proportional valve. The troubleshooting method is: clean the valve body and the front oil circuit, and replace the hydraulic oil and filter element

6. The traveling oil suction valve on the deflection side of the machine is damaged

the oil suction valve is installed on the hydraulic cylinder and motor of the working device. Its function is: when the hydraulic cylinder or motor is subjected to great external impact, it can be removed or when the motor is subjected to great external impact, the abnormal high pressure in the cylinder or motor can be removed (the set pressure is generally below 36.5mpa), so as to protect the relevant oil pipes and cylinders from damage. If the travel oil suction valve is damaged and the spring in the valve becomes soft or broken, the oil pressure in the travel main valve will be reduced, resulting in insufficient driving force of the travel motor and travel deviation. The troubleshooting is to repair or replace the oil suction valve

7. The action of the valve core of the main travel valve on the deflection side of the machine fails.

if the spring in the main travel valve becomes soft or broken, or the valve core is stuck, it may cause the oil pressure to decrease and the travel deviation. During the inspection, measure the pressure of the oil passage of the traveling main valve in cooperation with several mainstream raw material manufacturers in the automotive interior industry. The normal value should be 32.5mpa. If the main travel valve is damaged, replace or repair it. The PC200 excavator of our company has run off twice, which is caused by the damage of the main travel valve. Therefore, in case of traveling deviation fault, first consider whether the traveling main valve has been damaged to avoid detours

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