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14) In order to pressurize the hydraulic oil tank to retract the piston rod of the hydraulic cylinder.
Note: The oil level in the hydraulic oil tank will be slightly increased after this last operation.
Replace the hydraulic oil return filter element
The first replacement shall be carried out after working for 2000 hours, and thereafter it shall be done every 2000 hours.
1) Fully extend the piston rod of each hydraulic cylinder, and then stop the engine.
It shall be replaced or cleaned every 2000 hours thereafter. 2) Remove the oil tank plug to depressurize it.
3) Screw out the filter element 6 and replace it with a new one (grease the sealing washer before installation).
4) Start the engine and operate the excavating mechanism.
5) Check the hydraulic oil level and replenish it if necessary.
6) Retighten the screw plug and close the sight glass cover.
7) In order to pressurize the hydraulic oil tank to retract the piston rod of the hydraulic cylinder.
4. Discharge the air in the hydraulic system
A. Discharge the air in the pump
1) Loosen the exhaust screw plug in the exhaust port, and check whether there is oil flowing out. The exhaust is
completed.
2) Tighten the screw plug after the exhaust is completed.
Note: If the pump is operated if the pump is not full of oil, it will be abnormally heated and cause
premature damage to the pump.
B. Discharge the air between the pump and the hydraulic oil tank
1) Start the engine and keep it running at medium and low speeds.
2) Operate the working device slowly for about 5 minutes to discharge the air.
Note: If the air between the pump and the fuel tank is not discharged to allow the engine to run at a
high speed, it will also cause the pump to be heated and damage the pump.
C. Discharge the air in the oil cylinder
1) At low engine speed, extend and retract the oil cylinder to the position where is about 100 mm away from the stroke
end for 4-5 times. (Be careful not to extend or retract to the stroke end).
2) Then, operate each cylinder to the stroke end for 3 to 4 times.
3) Finally, operate each cylinder to the stroke end for 4~5 times to completely discharge the air.
Note: If the engine is operated at high speed or the oil cylinder is operated to the stroke end
immediately after starting the machine, the air in the oil cylinder will damage the piston seal and
damage the oil cylinder.
Summary of Contents for U27
Page 1: ...U27Hydraulic Excavator Instruction Manual Guangxi Yuchai Heavy Industry Co Ltd...
Page 5: ...1 1 Preface...
Page 17: ...2 1 Safety regulations...
Page 44: ...3 1 Parts introduction...
Page 49: ...3 6 Panel meter Oil level pointer Timing display Water temperature pointer Indicator area...
Page 55: ...4 1 Operation guide...
Page 89: ...5 1 Maintenance...
Page 130: ...6 1 Accessories guide...