What to Note When Starting Up New Hydraulic Equipment for The First Time

Whether it is a new hydraulic power unit, hydraulic press, construction machinery or automated hydraulic equipment, the first startup and commissioning directly determine the service life of the whole system. Many operators skip air bleeding and no-load running steps, and run the machine under full load and high pressure immediately. This wrong operation will scratch valve plates of piston pumps, damage cylinder inner walls, cause valve spool sticking, abnormal noise and internal leakage, and greatly shorten equipment service life. This article sorts out standard operating rules in three stages: pre-start inspection, low-speed running and full-load test.

1. Complete Inspection Before Startup (Mandatory Step)

1.1 Hydraulic Oil Filling Check

     Use hydraulic oil specified on the equipment nameplate. Never mix oil of different viscosity grades or brands. Fill oil to the standard liquid level marked on the tank. Low oil level will lead to pump cavitation and permanent pump damage. Filter the hydraulic oil during filling to prevent solid impurities entering the circuit.

1.2 Inspect All Pipelines and Seals

      Check if all hose joints, threads and flanges are loose after transportation. Check exposed seals on cylinder rods and valve blocks for impact damage. Ensure rigid pipes have no deformation, and flexible hoses are installed with standard bending radius without twisting.

1.3 Check Oil Tank and Filter Elements

      Confirm suction filters and return line filters are pre-installed intact. Remove all protective foam and plastic packing inside the oil tank to avoid foreign blockages.

1.4 Verify Motor Rotation Direction

     Jog the motor briefly to check rotation against the directional mark on the housing. Reverse rotation will cause zero pressure and harsh noise, and burn out the hydraulic pump quickly.

2. No-load Low-speed Running & Full Air Bleeding (Core Commissioning Step)

  2.1 Retract all hydraulic cylinders and hydraulic motors to the shortest stroke. Loosen all air vent screws on valve blocks and cylinder ends.

  2.2 Run the motor continuously with zero pressure for 5 to 10 minutes to expel trapped air inside pumps, valves, pipelines and cylinders. Keep venting until no continuous air bubbles flow out.

  2.3 Tighten all air vent screws after air removal. Control oil temperature below 40℃ during no-load operation. Shut down the machine immediately if oil temperature rises sharply.

  2.4 Check all connections for external leakage at all times. Stop pressure operation to tighten leaking joints; never repair seals under system pressure.

3. Staged Pressure Running, Never Full Load at First Startup

  3.1 Turn the relief valve to the minimum pressure setting at first, then increase pressure step by step in three stages: 30% rated pressure → 60% rated pressure → 80% rated pressure. Run at each pressure stage for more than 10 minutes without load.

  3.2 Watch cylinder and motor movement under low pressure. Stuttering, jitter or sharp noise indicates residual air inside the circuit, requiring repeated air bleeding.

  3.3 Test light loads gradually. Do not operate under full pressure and maximum load on the first startup. Violent fluctuation on pressure gauges means air entrapment in pumps or valves.

4. Full-load Test Run & Initial Maintenance

  4.1 If no abnormal conditions appear during staged pressure test, adjust the relief valve to standard working pressure and run the machine continuously under full load for 1 to 2 hours.

  4.2 Monitor oil temperature, operating noise and pressure stability during the whole test run. Record all operating conditions for later reference.

  4.3 Replace hydraulic oil and all filter elements within 24 hours after the first full-load test. Tiny metal particles generated during running will contaminate fluid; timely oil change protects precision mating surfaces of pumps and cylinders.

5. Strictly Forbidden Operations on New Hydraulic Machines

•   5.1 Do not pressurize the system without complete air bleeding; cavitation will permanently damage pumps.

•  5.2  Do not run the motor with reverse rotation for a long time.

•   5.3 Do not start the pump when the oil tank level is insufficient.

•   5.4 Do not run brand new equipment under full pressure and heavy load directly.

•   5.5 Do not mix different types of hydraulic oil.

Conclusion

The standard startup workflow for new hydraulic equipment includes four steps: comprehensive pre-inspection, sufficient air bleeding under no-load, staged low-pressure running, and slow full-load test. Standardized operation avoids premature hydraulic faults, extends the service life of pumps, cylinders and valves, and cuts long-term maintenance costs.