Floating Crane Hydraulic System Failures: 3 Common Issues, Self-Inspection & Solutions

The hydraulic system of a floating crane is the core of power transmission, responsible for the smooth operation of key actions such as lifting, slewing, and lowering. Failures in this system can directly cause equipment shutdown or operational loss of control, seriously affecting operational safety and efficiency. Targeting practical scenarios such as ports and marine engineering, the following introduces 3 major failure issues, along with self-inspection methods and solutions:

When the hydraulic system of a floating crane has insufficient pressure, the core manifestations are as follows:

• Weak lifting capacity; the marine crane cannot lift cargo to the rated lifting height.
• Slow and delayed responses during slewing and lowering operations of the hydraulic crane.
• The hydraulic pressure gauge displays a value lower than the rated working pressure (refer to the user manual for the specific rated pressure).

Inspection items

1. Check the hydraulic oil condition of the marine crane.

•  Whether it is below the minimum scale line (insufficient oil level will lead to inadequate oil suction and pressure drop).
• Whether it is turbid, contains air bubbles, or has an unusual odor (deteriorated oil or air contamination will affect pressure transmission).

2. Troubleshoot leakage points

• Check hydraulic pipelines, joints, and seals for oil leakage (leakage directly causes system pressure loss).
• Verify the integrity of seals at the cylinder and hydraulic pump shaft ends.

3. Confirm valve status

• Check if it is loose or if the valve core is stuck (failure to adjust the relief valve to the specified pressure will cause pressure relief).
• Check if it is switched in place and if the valve core is stuck (incomplete opening of the directional valve will lead to poor oil flow).

4. Simple tests

• Shut down the system, let it stand for 5 minutes, then restart and observe if the pressure is restored.
• If insufficient pressure only occurs during lifting, focus on inspecting the check valve in the lifting circuit.

Solutions

• If the oil level is insufficient: Add hydraulic oil of the same model to the normal level.
• If the oil quality deteriorates: Replace the hydraulic oil, check for clogged oil suction filters, and bleed air from the system.
• For leakage issues: Replace leaking joints and seals (use original equipment-compatible parts) and tighten loose pipeline bolts.
• Adjust the relief valve according to the pressure specified in the equipment manual (tighten clockwise to increase pressure, loosen counterclockwise to decrease pressure). If the valve core is stuck, disassemble and clean it with kerosene or special hydraulic oil cleaner; replace the valve if it cannot be repaired.

Specific manifestations are as follows:

• The outer shell of the hydraulic oil tank becomes excessively hot (too hot to touch) within 30 minutes of equipment operation.
• The high-temperature alarm light illuminates, and some equipment will automatically shut down for protection.
• Decreased oil viscosity, resulting in "soft operation" (weak and unstable movements).

Inspection Steps

1. Check the cooling system

• Observe the radiator: Whether it is clogged with dust or oil (poor heat dissipation is a major cause of hydraulic overheating).
• Inspect the cooling fan: Whether it starts normally (listen for rotation after power-on) and if the fan motor is faulty.
• Confirm the cooling water pipeline (for water-cooled systems): Whether it is unobstructed and if the inlet water temperature is too high (≤35℃).

2. Troubleshoot the hydraulic oil condition

• Check the oil level: An excessively high oil level reduces the heat dissipation area; an excessively low oil level causes rapid oil circulation and insufficient heat dissipation.
• Verify if different types of oil are mixed (mixed oil damages viscosity and increases friction-induced heating).

3. Inspect load and operation

• Check for prolonged overload operation.
• Check if the offshore crane's movements are too frequent (e.g., continuous lifting and slewing cause sustained high system pressure and heat accumulation).

Solutions

• Cooling system maintenance: Clean dust and oil from the radiator surface; repair or replace faulty cooling fans/motors; ensure unobstructed water-cooled pipelines and adjust water inlet flow.
• Hydraulic oil management: Adjust the oil level to the specified range; replace mixed or deteriorated oil; filter oil when refilling.
• Avoid prolonged overload operation: Stop and rest for 10-15 minutes after 1 hour of continuous operation to allow the system to cool naturally; reduce unnecessary frequent movements.

The main manifestations of abnormal noise in the deck crane hydraulic system are as follows:

• The hydraulic pump emits buzzing, clunking impact noises, or severe vibration during operation.
• Jerky movements (stuttering) occur during lifting and slewing.
• Severe equipment resonance affects operational accuracy.

If abnormal noise or vibration occurs in the hydraulic system, inspect the following key areas:

1. Check hydraulic oil and oil suction circuit

• Whether it is too low (exposing the oil suction port to air causes cavitation noise during suction).
• Whether it is clogged (clogging increases suction resistance and causes negative pressure noise).

2. Troubleshoot the pump and motor

•  Whether it is loose (loose mounting bolts cause vibration and noise).
•  Whether it is coaxial (misalignment causes transmission noise and accelerated wear).
•  Whether parts such as gears (for gear pumps) or vanes (for vane pumps) are worn (wear causes mechanical noise).

3. Inspect pipelines and valves

• Whether they are loosely fixed, high pressure causes pipeline vibration and collision noise.
• Whether the spools of directional valves or check valves are stuck .

Solutions

• First, bleed air and clean the filter: Add hydraulic oil to the normal level and bleed air from the system; disassemble and clean the oil suction filter with kerosene (replace if severely clogged).

• Tighten the mounting bolts of the hydraulic pump and pipelines; align the coaxiality of the motor-pump coupling.

• Component inspection and repair: If pump noise persists, disassemble and inspect internal parts (gears, vanes, bearings); replace the hydraulic pump if parts are severely worn. Clean stuck valve cores; replace valves if irreparable.

• Pipeline protection: Install shockproof clamps or rubber pads on severely vibrating pipelines to prevent collision.

The above methods focus on common high-frequency failures of floating crane hydraulic systems. With simple and easy-to-understand steps, they can effectively reduce downtime losses caused by minor faults. It is recommended to record failure phenomena and solutions in conjunction with the equipment operation manual to form a dedicated maintenance record handbook.

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