Excavator hydraulic oil replacement method

December 16, 2023

Excavator hydraulic oil replacement method

The hydraulic oil contained in the hydraulic tank of an excavator is 1/2 of the total oil used in the hydraulic system of the whole machine, and the remaining 1/2 hydraulic oil is stored in the hydraulic pump, motor, multiway valve, hydraulic cylinder and the pipelines of various parts. In the oil change, if only replace the hydraulic oil in the tank, rather than replace all the hydraulic oil in the vehicle hydraulic system, this method is only the old oil "ditch" new oil, if the two grades of hydraulic oil ditch together, it will cause oil deterioration.

For example, in a Sumitomo HS220 / excavator, the hydraulic system of the whole vehicle uses 420L hydraulic oil, and the hydraulic oil tank is 225L hydraulic oil, and the remaining oil is stored in the system. Various brands of excavator hydraulic system oil and tank volume ratio is consistent.

First, prepare for the replacement of hydraulic oil

1. When replacing the hydraulic oil of an excavator, the following preparations should be made: Purchase the oil for the hydraulic system of the whole vehicle. (2.5 times the volume of the hydraulic tank), filter element, washing oil, 3 kg of flour, rope, oil plug for sealing the hydraulic oil pipe, (according to the oil pipe preparation on the oil change excavator) a steam pump and size empty oil drum, etc. Get a normal excavator. The excavator arm of the oil change is raised to the highest point, and the engine is extinguished after the bucket rod and bucket receive the inner point (the cylinder rods of the boom cylinder, bucket rod cylinder and bucket cylinder are all extended to the apex).

2. Cleaning of the hydraulic tank: release all the hydraulic oil in the box, withdraw the hydraulic filter element, disassemble the pipeline between the pump and the tank from the interface of the pump, and release the oil in the pipeline. Flush hydraulic tank and line with wash oil. Clean the inside of the hydraulic tank with a medical cloth. The flour is divided into three parts to stretch the surface, and the dough is used to glue the inside of the hydraulic tank three times, especially the corners of the tank and the filter cartridge. The inside of the hydraulic tank and filter cartridge must be thoroughly cleaned. Replace the new hydraulic filter, good cover.

3. Washing of hydraulic plunger pump: Each hydraulic plunger pump on the excavator has a washing oil port (oil drain port). Unscrew the upper and lower oil ports, release the hydraulic oil in the pump shell, unscrew the oil plug under the pump, fill the pump shell with washing oil from the oil port above the pump, and then unscrew the oil plug under the pump, release the washing oil in the pump shell, rinse several times, and finally use the steam pump to blow the remaining oil in the pump shell, fill with clean hydraulic oil, and tighten the oil plug.

4. Replace the seal ring of the pump oil inlet (O-ring), connect the hydraulic tank to the oil supply pipeline of the pump, and fill the hydraulic tank with clean hydraulic oil from the oil port of the hydraulic filter element (put the replaced filter element).

Second, the oil change method of pushing out the old oil with new oil

1. Replace the hydraulic oil in the boom cylinder

Use the spare excavator to pull the excavator motor arm ready for oil change with a rope (at this time, the excavator motor arm ready for oil change has been raised to the highest point) to disassemble the rod-free oil tubing on the left and right boom cylinders, and use the spare empty oil drum to catch the released hydraulic oil. Pay attention to environmental protection and prevent environmental pollution. Then put the disassembled multi-way valve connected to the boom oil pipe in the spare empty oil drum, start the engine, then the hydraulic oil flowing from the multi-way valve to the boom oil pipe is the old hydraulic oil in the multi-way valve, the oil change personnel pay attention to the change in the color of the oil, when the new hydraulic oil flows out, immediately make the engine off. Connect the disconnected pipe, unhook the rope, start the engine, and repeatedly raise and drop the boom until the boom cylinder is filled with oil. Only this single action is allowed. Pay attention to check the liquid level change in the hydraulic tank, and add the missing hydraulic oil in time.

2, bucket rod cylinder hydraulic oil replacement

After the boom is raised to the highest point, (only this single action is allowed) the engine is turned off, (at this time the bucket rod cylinder rod is all extended), and the tubing with the rod cavity of the bucket rod cylinder is disassembled from the multi-way valve, and the oil in the pipeline is discharged, and the pipeline is connected again. Then from the back of the boom to disassemble the rod cylinder rodless cavity of the tubing, oil plugging the disassembled multi-way valve and rod cylinder rodless cavity tubing. Use the spare oil barrel to prepare the hydraulic oil released from the bucket cylinder, start the engine, withdraw the bucket rod cylinder piston rod (as shown in Figure 2, the bucket rod is retracted into the cylinder). After connecting the disassembled tubing, start the engine, expand and expand the bucket rod cylinder piston rod several times, place the bucket rod at a vertical ground Angle, and the engine is turned off and the oil is changed.

3. Replace the hydraulic oil in the bucket cylinder

Disassemble the tubing in the rodless chamber of the bucket cylinder from the back of the boom, and plug the removed multiway valve and the hose oil port of the bucket cylinder with oil. Use the empty oil drum to catch the disconnected oil port on the arm cylinder, start the engine, do the bucket action, (cylinder piston rod all retracted into the cylinder), can only do this single action. The new hydraulic oil enters the rod cavity of the bucket cylinder, and after the piston rod is retracted, all the hydraulic oil in the rodless cavity of the bucket cylinder is discharged into the empty oil barrel. Engine off, connect disconnected tubing. Pay attention to the position of the gauge oil level on the hydraulic tank.

4. Oil replacement of rotary motor system

Remove either of the two oil pipes from the multiway valve to the rotary motor. Plug the outlet of the multiway valve and rotary motor with oil plug. Connect the spare empty barrel to the disassembled oil port of the rotary motor, start the engine, and control the excavator to turn slowly. If you rotate in a certain direction, the oil pipe on the motor must rotate in the other direction until the oil flows out, that is, the operation is correct. At the same time, pay attention to the color change of the outflow oil, and shut down the engine immediately after the new hydraulic oil flows out. Connect the oil pipe of the disconnected rotary motor and complete the oil change.

5. Replace the hydraulic oil of the hydraulic system of the walking motor

Use the excavator motor arm to lift the walking track on one side of the excavator, and remove the side cover of the walking motor on the inside. Disconnect any of the two inlet and outlet oil pipes of the traveling motor, plug the disconnected inlet oil pipe with oil, connect the spare empty oil drum to the oil outlet of the traveling motor, start the engine, operate the walking control valve that has been supported on this side, and start the track to turn until the new oil flows out of the oil outlet of the traveling motor. At this time, immediately shut down the engine and connect the disconnected oil pipe. Then use the same method to replace the traveling motor on the other side and the hydraulic oil in the system. When replacing the hydraulic oil in the hydraulic system of the traveling motor in this way, be careful not to make operation errors. If the track on the side that is not supported is turned by mistake, the old hydraulic oil in the traveling motor system will flow back into the hydraulic tank.

Three, oil change precautions

1. The oil tank, hydraulic piston pump, boom cylinder, bucket rod cylinder, bucket cylinder, rotary motor and left and right walking motor can not be changed. Different items, can only manipulate the corresponding parts to make its action, to avoid if there is an operation error.

2, the quality requirements of hydraulic oil

The service life of the excavator is directly related to the quality of the hydraulic oil, and the quality of the hydraulic oil that meets the quality standard certification of the American Society of Engineers should be selected, and the viscosity index of the hydraulic oil is stable at 40°~100°C. The same brand of hydraulic oil must be used during replacement.

3, the viscosity of hydraulic oil requirements: hydraulic oil has N32HL, N46HL and N68HL three types of anti-wear hydraulic oil. Excavators with a service life of 1,000h should use N46HL+N68HL anti-wear hydraulic oil (50% each). N68HL anti-wear hydraulic oil for excavators with more than 15,000 hours.

4, the service life of hydraulic oil

The service life of hydraulic oil is 4000~6000h hours, which is about two years. In the spring and autumn of each year, the temperature difference between day and night is large, after the excavator stops working at night, the oil inside the hydraulic tank is high temperature, the air outside the tank is low temperature, the hot air in the tank and the cold air outside the tank meet and contact, it will be cold condensed into water droplets on the top of the tank and fall in the hydraulic oil, over time, the hydraulic oil will be mixed with water. It then turns into an acid that eats away at the metal surface. Under the double action of mechanical operation and pipeline pressure impact, the metal particles falling off the metal surface will be mixed in the hydraulic oil, the large metal particles are filtered out, and the particle hydraulic filter element less than 10μm can not be filtered out, and the grinding particles mixed in the hydraulic oil will aggravate the wear of the metal surface again.

5, the choice of hydraulic oil filter

The filtration accuracy is 10μm50%, the pressure range is 1.4 to 3.5MPa, the rated flow rate is 40 to 400L/min, and the recommended replacement time is 500h.

6, all disassembled tubing must replace the seal. (O-ring) When connecting, the thread surface should be coated with thread sealant to prevent leakage.

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