Preparation stage
Confirm the hydraulic oil specification: The斗山 55 machine usually uses anti-wear hydraulic oil with viscosity grades of ISO VG46 or VG68, which must comply with the requirements of the equipment manual.
Tools and materials: New hydraulic oil (approximately 50-80 liters, depending on the tank capacity), hydraulic oil filter element (including return oil filter element and suction oil filter element), oil drain container, wrench, filter element wrench, cloth, funnel, liquid level gauge.
Safety measures: Park the equipment on a flat surface, turn off the engine and pull up the handbrake, and hang a "Under Maintenance" warning sign.
Discharge old hydraulic oil
Locate the oil drain port: The bottom of the hydraulic oil tank usually has an oil drain screw. For some models, the guard plate needs to be removed first.
Discharge procedure: Unscrew the oil drain screw and allow the old oil to flow into the container until it is completely drained.
If the hydraulic system has multiple oil circuits (such as the main pump and the rotating motor), the residual oil must be drained separately (professional guidance is required).
Clean the fuel tank: Use a cloth to remove the oil stains inside the tank and around the oil drain hole to prevent impurities from entering.
Replace the filter element
Return oil filter: Located on the top or side of the hydraulic oil tank. Remove the old filter using the filter wrench, replace it with a new one and seal it.
Oil intake filter (if present): Some models have an oil intake filter at the inlet of the hydraulic pump. The pump body cover needs to be removed for replacement.
Main pump filter element (optional): According to the maintenance cycle, the main pump inlet filter element can be replaced simultaneously.
Add new hydraulic oil
Instruction for adding oil: Add new oil through the oil filler port of the hydraulic tank or using a dedicated filling pump.
Fill the tank below the "MAX" line on the level gauge (to avoid overfilling).
Exhaust operation: Start the engine and run it at low speed for 5 to 10 minutes to allow the hydraulic oil to circulate.
Operate each actuating mechanism (such as the boom and the bucket) several times to expel the air from the system.
After the machine stops, check the liquid level and refill it to the standard range.
Inspection and Testing
Leakage inspection: Observe whether there is oil leakage at the hydraulic pipelines, joints, and filter element sealing areas.
Performance test: Operate the equipment to perform digging, rotating, etc., and confirm that there are no abnormal noises or slow movements.
Record maintenance: Record the oil change date, oil type and filter replacement status in the equipment maintenance manual.
Notes:
It is prohibited to mix different brands or models of hydraulic oil to avoid chemical conflicts.
When replacing the filter element, avoid allowing dust to enter the interior of the filter.
If the equipment has been unused for a long time or the hydraulic oil has deteriorated severely, it is recommended to contact Doosan's after-sales service for a system cleaning.
Reference: Section "Hydraulic System Maintenance" of the "Operation and Maintenance Manual" of Doosan DX55 Excavator.
