Hydraulic systems are the "heart" of excavators, responsible for powering boom, arm, bucket movements and all heavy-duty operations. Stable hydraulic performance directly determines construction efficiency and equipment lifespan. Below are systematic, science-based maintenance guidelines for excavator hydraulic systems.
Oil selection: Always use the original factory-recommended hydraulic oil (e.g., ISO VG 46/68 for SANY excavators), matching the working temperature range of your region. Low-quality oil will accelerate wear of pumps, valves and cylinders, and cause seal failure.
Oil replacement cycle: Replace hydraulic oil and filter elements according to the manual (usually every 2000 operating hours). In harsh working conditions (dust, high temperature, waterlogging), shorten the interval by 30%.
Oil contamination control: Keep the oil tank cover sealed tightly; avoid exposing the oil to open air during refueling. Water and particulate contamination are the main causes of hydraulic system failure—water can emulsify oil and corrode metal parts, while particles will scratch cylinder walls and block valves.
Hose inspection: Check all hydraulic hoses for cracks, bulges, abrasion or oil leakage. High-pressure hoses are prone to fatigue failure under long-term vibration; replace them immediately if any damage is found.
Seal maintenance: Check cylinder rod seals, valve block seals and pipe joints for oil leakage. Replace worn seals in time—leakage not only causes oil loss but also allows air and dust to enter the system, leading to cavitation and slow response.
Prevent brittle failure: In high/low temperature environments, rubber seals and hoses become more fragile—avoid sudden impact or over-twisting during operation.
Clean radiator: The hydraulic oil radiator is easily blocked by dust, mud and debris, which will cause oil temperature to rise sharply. Clean the radiator surface with compressed air or low-pressure water regularly (every 500 hours).
Temperature monitoring: Keep hydraulic oil temperature between 40–80°C during operation. Excessively high temperature (>90°C) will accelerate oil oxidation, reduce lubricity and soften seals, leading to system failure.
Avoid idling for long periods: Prolonged idling with no load will cause the hydraulic system to circulate oil internally, generating unnecessary heat—shut down the engine during long breaks.
Air bleeding: After replacing hydraulic oil, filters or disassembling hydraulic components, bleed air from the system by running the boom/arm/bucket through full strokes several times. Trapped air will cause jerky movement, noise and cavitation damage.
Cavitation prevention: Ensure the oil level in the hydraulic tank is within the specified range (not too low). Cavitation occurs when low pressure causes oil to vaporize, forming bubbles that collapse and erode metal surfaces of pumps and valves.
Pre-operation: Check the hydraulic oil level via the tank gauge; ensure it is between the MIN and MAX marks. Start the engine and idle for 3–5 minutes, then test the boom, arm and bucket movements to confirm no abnormal noise or slow response.
Post-operation: Clean mud and debris from hydraulic cylinders and hoses. Check for any oil leakage points and record them for timely repair. Park the excavator on level ground to prevent oil from seeping into unintended areas.