1. The balance valve in the parking brake oil circuit where dirt enters the machine side
When the machine walks, if the dirt plugs the small hole of the balance valve, the parking brake cannot be released, resulting in running deviation. When the machine is walking, if the pressure oil cannot enter the spring chamber of the counterbalance valve through the small hole of the counterbalance valve to push the counterbalance valve spool to move, the pressure oil cannot enter the hydraulic system through the slot in the counterbalance valve, resulting in a parking system. The power cannot be relieved. As a result, the walking motor cannot be rotated, and therefore walking deviation occurs. Remedy method; Clean the balance valve; When disassembling, avoid the entry of dirt; replace hydraulic oil and filter element that meet the requirements regularly.
2, the center rotary joint seal ring is damaged
The center swivel joint consists of a shell and a mandrel. The shell is mounted on the upper body and the mandrel is mounted on the lower body. The mandrel is provided with an annular groove equal to the number of oil pipes. The hydraulic oil from the housing flows through these oil grooves from the vertical hole in the mandrel to the traveling motor. Therefore, even if the housing continuously rotates with the upper body, the mandrel The groove can also keep open with the oil port on the housing. Allows hydraulic oil to 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 hydraulic oil is not filtered so that the impurities in the oil directly enter the sliding surface of the center swivel joint, causing damage to the seal ring on the center rotary joint. When walking, one side of the pressure oil leakage caused the speed of the two sides of the traveling motor is not the same, resulting in the machine walking deviation. The exclusion method is: replace the center rotary joint oil seal; replace the hydraulic oil and filter element.
3, dirt plug hole in the balance valve of the final drive system, resulting in the parking brake can not be lifted
When the machine is walking, if the pressure oil cannot push the balance valve spool to move through the small hole in the balance valve, the pressure oil can not release the parking brake force through the slot in the balance valve, resulting in the normal rotation of the traveling motor, resulting in excavation. Walk away. The exclusion method is: cleaning the balance valve; when disassembling, must avoid the entry of dirt.
4. Travel motor safety valve leaks
If the safety valve leaks, it will cause the pressure in the system to be too low, making the rotational speed of the traveling motor insufficient, thus causing running deviation. The remedy method is: replace the damaged travel motor safety valve; when judging, you can replace the left and right travel motor safety valves to see if they are deflected when walking backwards.
5. The output pressure (pressure control) of the walking proportional valve on the side of the machine deflection is too low
The proportional valve can output the corresponding control oil pressure according to the length of the control handle control stroke, so that the main control valve has a corresponding amount of movement, thereby controlling the speed of the working device. Failure to change the filter element of the oil filter on time can result in plugging of the filter element and opening the bypass valve of the oil filter. The dirty hydraulic oil will directly enter the circuit of the proportional valve without filtering, resulting in the valve inside the valve being When it is stuck, the control oil cannot flow through the rotary proportional valve on the side of the machine to the rotary main control valve, resulting in running deviation. When checking, check the pressure of the running proportional valve (3.3MPa). The troubleshooting method is: clean the valve body and the front oil circuit, replace the hydraulic oil and the filter element.
6. Damaged walking suction valve on the side of machine deflection
The suction valve is mounted on the hydraulic cylinder and motor of the working device. Its role is: When the hydraulic cylinder or motor is subjected to a large external impact force, when it can be removed or the motor is subjected to a large external impact, the abnormal high pressure in the cylinder or motor can be removed (the set pressure is generally below 36.5 Mpa). Protect related tubing and cylinders from damage. If the traveling suction valve is damaged and the spring in the valve becomes soft or broken, the hydraulic pressure in the traveling main valve will be reduced, resulting in insufficient driving force of the traveling motor and causing running deviation. The remedy is to repair or replace the suction valve.
7. Malfunction of the main spool of the main valve on the side of the machine deflection
If the spring in the running main valve softens or breaks, or if the valve plug is stuck, it may cause the oil pressure to decrease and cause running deviation. During the inspection, the pressure of the oil on the main running valve must be measured. The normal value is 32.5 Mpa. If the main travel valve is damaged, it should be replaced or repaired. My unit's PC200 excavator had walked and walked twice. It was caused by damage to the running main valve. Therefore, in the event of a walking deviation, it should first consider whether the main valve has been damaged, to avoid detours.
When the machine walks, if the dirt plugs the small hole of the balance valve, the parking brake cannot be released, resulting in running deviation. When the machine is walking, if the pressure oil cannot enter the spring chamber of the counterbalance valve through the small hole of the counterbalance valve to push the counterbalance valve spool to move, the pressure oil cannot enter the hydraulic system through the slot in the counterbalance valve, resulting in a parking system. The power cannot be relieved. As a result, the walking motor cannot be rotated, and therefore walking deviation occurs. Remedy method; Clean the balance valve; When disassembling, avoid the entry of dirt; replace hydraulic oil and filter element that meet the requirements regularly.
2, the center rotary joint seal ring is damaged
The center swivel joint consists of a shell and a mandrel. The shell is mounted on the upper body and the mandrel is mounted on the lower body. The mandrel is provided with an annular groove equal to the number of oil pipes. The hydraulic oil from the housing flows through these oil grooves from the vertical hole in the mandrel to the traveling motor. Therefore, even if the housing continuously rotates with the upper body, the mandrel The groove can also keep open with the oil port on the housing. Allows hydraulic oil to 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 hydraulic oil is not filtered so that the impurities in the oil directly enter the sliding surface of the center swivel joint, causing damage to the seal ring on the center rotary joint. When walking, one side of the pressure oil leakage caused the speed of the two sides of the traveling motor is not the same, resulting in the machine walking deviation. The exclusion method is: replace the center rotary joint oil seal; replace the hydraulic oil and filter element.
3, dirt plug hole in the balance valve of the final drive system, resulting in the parking brake can not be lifted
When the machine is walking, if the pressure oil cannot push the balance valve spool to move through the small hole in the balance valve, the pressure oil can not release the parking brake force through the slot in the balance valve, resulting in the normal rotation of the traveling motor, resulting in excavation. Walk away. The exclusion method is: cleaning the balance valve; when disassembling, must avoid the entry of dirt.
4. Travel motor safety valve leaks
If the safety valve leaks, it will cause the pressure in the system to be too low, making the rotational speed of the traveling motor insufficient, thus causing running deviation. The remedy method is: replace the damaged travel motor safety valve; when judging, you can replace the left and right travel motor safety valves to see if they are deflected when walking backwards.
5. The output pressure (pressure control) of the walking proportional valve on the side of the machine deflection is too low
The proportional valve can output the corresponding control oil pressure according to the length of the control handle control stroke, so that the main control valve has a corresponding amount of movement, thereby controlling the speed of the working device. Failure to change the filter element of the oil filter on time can result in plugging of the filter element and opening the bypass valve of the oil filter. The dirty hydraulic oil will directly enter the circuit of the proportional valve without filtering, resulting in the valve inside the valve being When it is stuck, the control oil cannot flow through the rotary proportional valve on the side of the machine to the rotary main control valve, resulting in running deviation. When checking, check the pressure of the running proportional valve (3.3MPa). The troubleshooting method is: clean the valve body and the front oil circuit, replace the hydraulic oil and the filter element.
6. Damaged walking suction valve on the side of machine deflection
The suction valve is mounted on the hydraulic cylinder and motor of the working device. Its role is: When the hydraulic cylinder or motor is subjected to a large external impact force, when it can be removed or the motor is subjected to a large external impact, the abnormal high pressure in the cylinder or motor can be removed (the set pressure is generally below 36.5 Mpa). Protect related tubing and cylinders from damage. If the traveling suction valve is damaged and the spring in the valve becomes soft or broken, the hydraulic pressure in the traveling main valve will be reduced, resulting in insufficient driving force of the traveling motor and causing running deviation. The remedy is to repair or replace the suction valve.
7. Malfunction of the main spool of the main valve on the side of the machine deflection
If the spring in the running main valve softens or breaks, or if the valve plug is stuck, it may cause the oil pressure to decrease and cause running deviation. During the inspection, the pressure of the oil on the main running valve must be measured. The normal value is 32.5 Mpa. If the main travel valve is damaged, it should be replaced or repaired. My unit's PC200 excavator had walked and walked twice. It was caused by damage to the running main valve. Therefore, in the event of a walking deviation, it should first consider whether the main valve has been damaged, to avoid detours.
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