Maintenance knowledge of the travel motor

Updated: Aug 18, 2018

1. Whether it is large digging or small digging, try to walk as short as possible. If the long-distance walking distance is too long, it will damage the digging machine's walking wheel. When walking, try to make the road flat, especially when walking in constant time and adding uphill. You must use a slow gear, if necessary, use a hook to match, do not let the walk have too much compound which is very hurt walking.

2. The planetary gear box must be filled with gear oil. After the initial use, the gear oil should be replaced once every three months. After that, the gear oil should be replaced every one year according to different working conditions. After the running motor runs for a period of time, the rear cover of the gear box should be disassembled, and the wear of the gear box should be checked regularly for timely maintenance.

        3. During the operation of the traveling motor, the working condition of the system oil circuit and the motor gear oil should be checked frequently. If the system pressure is abnormally increased, the traveling motor leaks, abnormal temperature rise, vibration noise or abnormal pressure pulsation, stop immediately. Identify the cause and promptly overhaul.

       4. When the excavator's travel motor is weak or the system has abnormal conditions, it should stop immediately and check whether the leakage of the hydraulic motor is normal. If there is a large amount of leakage, the hydraulic motor is damaged and needs to be repaired or replaced.

       5. It is recommended to stop the excavator travel motor for 1-2 hours after continuous operation for 15 minutes.

6. The safety motor is set to drive the circuit of the traveling motor. For example, the hydraulic motor is a radial piston motor, the relief pressure setting value does not exceed 22 MPa, the hydraulic motor is a cycloidal hydraulic motor, and the overflow pressure does not exceed 17 MPa. The setting pressure of the motor relief valve can be up to about 35Mpa according to the requirements of the host equipment.

7. Control the running hydraulic circuit The steering control of the reversing valve in the neutral position must be "Y" or "H".

8. The hydraulic oil is too dirty and will affect the service life of the excavator travel motor.

Reasons for slow walking and troubleshooting

1 Center swivel joint seal is damaged

The central swivel joint is composed of two parts: a casing and a mandrel. The mandrel is mounted on the lower body, and the casing is mounted on the upper body. The mandrel is provided with an annular groove equal to the oil pipe. The hydraulic oil from the main spool flows through the casing from the vertical hole on the mandrel to the motor, the casing continuously rotates with the upper body, and the groove on the mandrel can also be kept open to the oil port on the casing, hydraulic The oil can enter and exit freely on the center joint. 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 rotary joint, so that the seal ring on the filter is damaged. When walking, the speed of the running motor on both sides is different due to the leakage of pressure oil on one side, and the result is that the excavator is traveling away. The method of elimination is: when replacing the oil on the center swivel joint, replace the hydraulic oil and filter element at the same time.

2 Dirty material enters the balance valve in the parking brake oil circuit on the excavator side

When the excavator walks, if there is dirt blocking the small hole of the balance valve, the parking brake can not be released, causing the walking deviation. This is because if the excavator is walking, the pressure oil cannot enter through the small hole of the balance valve. When the spring chamber of the balance valve pushes the balance valve spool to move, the pressure oil cannot enter the hydraulic system through the groove on the balance valve, so that the parking brake force cannot be released, and as a result, the travel motor cannot rotate, so the travel deviation also occurs. . Remedy: Remove the balancing valve and clean it. When disassembling, no dirt can enter. Regularly replace the hydraulic oil and filter element that meet the requirements.

3 travel motor safety valve oil leakage

The leakage of the travel motor safety valve will cause the pressure in the system to be too low to make the travel motor run insufficiently, so that the walking deviation correction method occurs: replace the damaged travel motor safety valve. When judging, the safety valve of the left and right travel motors can be swapped to see if it is deflected during reverse travel.

4 The dirt blocks the small hole K of the balancing valve of the final drive system, causing the parking brake to not be released.

When the excavator is walking, if the pressure oil cannot push the balance valve spool to move through the small hole K on the balance valve, the pressure oil cannot pass the groove on the balance valve to release the parking power, resulting in the traveling motor not rotating normally, resulting in the traveling motor being unable to rotate normally. The excavator walks away. Remedy: Clean the oil circuit, and pay attention to avoid the entry of dirt in the future, and replace the hydraulic oil and filter element on time.

5 Excavator deflection of the main valve spool malfunction

 If the spring in the main valve is soft or broken, or the spool is stuck, it may cause the oil pressure to drop and the running deviation. During the inspection, the pressure of the main valve oil circuit should be measured. The normal value should be 30.5 MPa. If the main valve is damaged and needs to be replaced or repaired, we have encountered the Daewoo DH220LC-V excavator running deviation. The inspection result is the main valve. Caused by the damage ring, in the event of a running deviation, the first consideration should be considered whether the main spool has been damaged.

6 The suction valve on the deflection side of the excavator is damaged.

The suction valve is mounted on the hydraulic cylinder and motor of the working device. Its function is: when the hydraulic cylinder or motor is greatly impacted by the outside, the abnormal high pressure in the hydraulic cylinder or the motor can be removed, thereby protecting the relevant oil pipe and the cylinder from damage. If the walking suction valve is damaged and the spring inside the valve is soft or broken, the oil pressure in the running main valve will be lowered, resulting in insufficient driving force of the traveling motor and causing deviation. Remedy: Repair or replace the suction valve.

7 Track tension is different

If the excavator is walking, the degree of tension on the left and right sides of the track will be different, which will also make the deviation when walking. Troubleshoot: Fill the loose side with butter to make it the same as the other side.

8 large pump performance degradation

When the excavator is walking straight, when the plunger of the pump flow regulator of one of the pumps is stuck in a certain position, or because the wear is serious, the internal leakage occurs, the system pressure can only reach 29.5 MPa, which makes the speed of the traveling motor slow. The excavator will run off. Remedy: Remove the hydraulic pump assembly from the excavator, replace the worn parts, repair the regulator, and replace the hydraulic oil and filter element.

9 The output pressure of the running proportional valve on the deflection side of the excavator is too low

The proportional valve can output the corresponding control oil pressure according to the length of the operating handle control stroke, so that the main control valve has a corresponding movement amount, thereby controlling the speed of the working device. Failure to change the filter element of the oil filter on time may cause the filter element to clog, causing the oil filter bypass valve to open, and the dirty hydraulic oil directly enters the proportional valve circuit without being filtered, causing the spool valve in the valve to be blocked. If it is stuck, the control oil will not flow to the rotary main control valve through the rotary proportional valve on the side of the excavator, causing the running deviation. At this time, check the pressure of the running proportional valve (3.3 MPa). Remedy: Clean the valve body and the front oil circuit, and replace the hydraulic oil and filter element.

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