Matters needing attention in replacing hydraulic oil with hydraulic excavator?

Hydraulic excavators generally need to replace hydraulic oil after working for 2000 hours, otherwise the system will be polluted and the hydraulic system will fail. According to statistics, about 90% of hydraulic system failures are caused by system pollution. This paper introduces the process steps and matters needing attention of replacing hydraulic oil with hydraulic excavator.

First, the preparation work of hydraulic excavator to replace hydraulic oil 1, familiar with the working principle, operating procedures, maintenance and use requirements of hydraulic system, so as to know fairly well and not blindly. 2. Prepare new oil according to the oil quantity specified in the instruction manual, and the new oil should be precipitated for no more than 48h before use. 3. Prepare tools for disassembling each pipe joint, oil filter for filling new oil, filter element of hydraulic system, etc. 4. Prepare cleaning solution, brush and rag for wiping. 5. Prepare oil tongs for waste oil. 6. Choose a flat and solid site to ensure that the machine can rotate without obstacles when the bucket and bucket arm are completely abduction. After the boom is completely hoisted, it will not encounter any obstacles, and the distance from the wire should be more than 2m. 7. Prepare 4 sleepers to block the track in front and back. 8. There should be at least four operators, including a driver, a field commander and two oil changers.

Second, the method and steps of hydraulic excavator replacing hydraulic oil

1. Place the boom parallel to the crawler, turn it 45 to the left and stop, so that the piston rod of the bucket cylinder is fully extended, and the piston rod of the stick cylinder is fully retracted. Slowly lower the boom and put the bucket on the ground. Then, turn off the engine, open the fuel tank bleeder valve, and pull the operating handle and pedal several times to release the residual pressure caused by the dead weight of the system.

2. Thoroughly clean each pipe joint, pump and motor joint, oil drain plug, top oil filler cap, bottom oil drain plug and their surroundings of the oil tank with gasoline.

3. Open the oil valve and oil drain plug at the bottom of the oil tank, so that all the old oil flows into the oil drum filled with waste oil.

4. Open the fuel tank cover, take out the fuel filter, and check whether the residual oil at the bottom of the fuel tank and its edges and corners contains metal powder or other impurities. Thoroughly clean the oil tank, first clean it twice with diesel oil, and then blow dry the inside of the oil tank with compressed air. Check the internal corners for residual sludge and impurities until they are cleaned, and then rinse them with new oil.

5. Remove the following oil pipes: ① Remove the oil pipes in the oil return circuit, such as the oil pipes from the main control valve to the full-flow filter and oil return filter, and the oil pipes from the filter to the oil tank and oil cooler. ② Remove the oil return pipe from the rotary control valve to the filter and the oil supply pipe of the rotary motor. ③ Remove the oil inlet pipe of the hydraulic pump. ④ Remove the oil pipe of the pilot system oil return circuit. ⑤ Remove the oil drain pipe of the main pump and motor. Thoroughly clean its pipes. Clean the steel pipe twice with diesel oil, clean the hose twice with cleaning solution, then blow dry with compressed air, and then rinse with new oil. All joints should be plugged with nylon or covered with clean plastic sheets to prevent dust and moisture from entering and polluting the system.

6. Remove the filter elements of all filters in the system. When replacing the filter element, carefully check whether there is metal powder or other impurities on the filter element, so as to understand the wear of parts in the system.

7, put off the main hydraulic pump, rotary motor, walking motor cavity of the old oil, and filled with new oil.

8. Install the dismantled pipes. Before installing each oil pipe, be sure to clean the pipe joint again and wipe it with silk. It is forbidden to wipe the pipe joint with cotton yarn, towels and other fiber fabrics. When installing the threaded joint, the sealing tape should be used, and its sticking direction should be opposite to the thread rotation direction. Pipe joints shall be installed and connected in turn according to the specified torque.

9. Fill the fuel tank from the filler. Install the oil filter first, then open the new oil drum, use the oil filter to inject new oil into the oil tank, add it to the upper limit of the oil mark, and cover the oil tank cover.

10. Replace the old oil in the following action circuits. Before changing oil in each circuit, the machine should be in three states: the piston rod of the bucket cylinder is fully extended, the piston rod of the stick cylinder is fully retracted, and the bucket is freely placed on the ground.

① Pilot control system loop. Disassemble the control oil pipe joints of the parking brake of the left and right traveling motors, so that the selector valve is in the middle position, drive the engine to idle for several times with the starter motor, and drain the old oil in the oil supply pipeline of the pilot system, then clean the pipe joints and connect them properly; Start the engine, run at idle speed for 5 minutes, then loosen the pilot oil pipe joints on the control valve respectively, and operate each action back and forth until new oil is discharged, then clean each pipe joint and connect it properly.

② Boom circuit. Put the bucket on the ground, pull the handle back and forth several times, remove the tubing joint of the boom cylinder without rod cavity, and drain the old oil in the rod cavity of the hydraulic cylinder, then operate the boom handle and slowly pull the handle in the lifting direction until the new oil is drained from the joint, and then clean the tubing joint and connect it well; Loosen the tubing joint with rod cavity in the boom cylinder, operate the boom handle, and slowly pull the handle in the landing direction until the tubing discharges new oil; Operate the handle of the boom, slowly pull the handle in the lifting direction, drain the old oil in the rod cavity, clean the pipe joint and connect it; Operate the boom to ascend and descend several times to exhaust the air in the system.

③ Barrel circuit. Loosen the oil pipe with rod cavity in the bucket cylinder, operate the handle, and slowly pull the handle along the direction of outward rotation of the bucket until new oil is discharged from the pipe joint, then clean the pipe joint and connect it; Disassemble the tubing joint without rod cavity, slowly lift the boom to make the bucket about 1 .5m off the ground, then slowly operate the handle of the bucket to turn it to the top, and lower the boom to make the bucket touch the ground. Operate the handle of the bucket, slowly pull the handle in the direction of internal rotation of the bucket to discharge the old oil in the oil pipe, clean the pipe joint and connect it; Lift the boom so that the bucket is 2.5 meters off the ground, and turn the bucket inward and outward several times to exhaust the residual air in the loop.

(4) adhere to the circuit. Dismantle the tubing joint without the rod cavity of the bucket cylinder, operate the handle, slowly pull the handle in the direction of the bucket's internal rotation, drain the old oil in the tubing until the new oil flows out, clean the tubing joint and connect it; Loosen the pipe joint with the rod cavity of the bucket oil cylinder, release the old oil in the rod cavity, slowly pull the handle in the direction of the outward rotation of the bucket, spray the old oil out of the pipe until the new oil is discharged, clean the pipe joint and connect it; Lift the boom and turn the stick inward and outward several times.

⑤ Rotating system. Remove the right oil pipe connector on the rotary control valve, operate the rotary handle, slowly turn it to the right, and then insert the rotary lock pin. When no old oil is discharged, clean the pipe joint and connect it. Drain the old oil from the left swing buffer brake valve in the same way.

⑥ Walking system. One side supports the left crawler, the round surface of the bucket should touch the ground, and the included angle between the boom and the bumper should be 90 ~110; Remove the front oil pipe joint on the left travel control valve, press the left travel pedal to make the left crawler move forward slowly until new oil is discharged from the oil pipe joint, then clean the oil pipe joint and connect it. Use the same method to drain the old oil in the right walking pipeline.

1 1. After changing all the oil and connecting all the pipe joints, the residual air in the system must be exhausted again, because these residual air will cause poor lubrication, vibration, noise and performance degradation. Therefore, the engine should run for at least 5 min after oil change, and then slowly operate the boom, bucket, bucket and rotary motion several times; If the walking system is in the state of supporting the crawler on one side, hydraulic oil can fill the whole system, and the residual air after exercise will be automatically discharged through the oil tank. Finally, close the bleeder valve.

12 Recheck the oil level in the fuel tank. Extend the piston rod of the bucket cylinder completely, retract the piston rod of the stick cylinder completely, and lower the boom to make the bucket touch the ground; Check whether the oil level in the oil tank is between the upper and lower limits of the oil level gauge. If the oil level is lower than the lower limit, add oil until the oil level approaches the upper limit.

3. When hydraulic excavator changes hydraulic oil, the following matters must be paid attention to: (l) It is forbidden to start the engine when the oil tank is not full and the cavity of hydraulic pump and motor is not full; (2) In the process of oil change, stops must be placed before and after the crawler, and locking pins must be inserted into the slewing mechanism; When the bucket, stick and boom move, it is forbidden to stand under them or within the action range; (3) When disassembling each pipe joint, the system must be freely placed on the ground, and the pipeline can be disassembled after confirming that there is no pressure. When disassembling, people should try to avoid the direction of joint oil leakage; Wear protective glasses at work; (4) When the upper part of the excavator rotates or walks, the driver must honk the horn and give a warning. It is forbidden to stand above, and within the range of track and rotation; (5) When disassembling, do not damage the joint surface and thread of each pipe joint of the hydraulic system; (6) Smoking and open flames are strictly prohibited at the work site; (7) When hydraulic excavator replaces hydraulic oil, it is best to finish it on the same day, not overnight, because at night or when the temperature drops, the moisture in the air will form water vapor, which will condense into water drops or frost, and enter the system to rust metal parts, causing hidden dangers.

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