Marine hydraulic cylinders are key actuators in ship hydraulic systems and are widely used in many important systems such as steering gears, cranes, hatch operations, and adjustment systems. If the hydraulic cylinder does not move, it may cause the entire system to fail, seriously affecting the normal operation of the ship. In order to troubleshoot, you first need to understand the common reasons why the hydraulic cylinder does not move and take corresponding solutions.
The following are several common reasons and analysis for the failure of marine hydraulic cylinders:

1. Common reasons for the failure of hydraulic cylinders
Missing hydraulic oil or low oil level
Cause analysis:
If the hydraulic oil level is too low, the oil pump cannot provide enough hydraulic oil, resulting in the hydraulic system being unable to generate enough pressure and the hydraulic cylinder failing to move normally.
Solution:
Check the hydraulic oil level and refill it to the normal range. Check the amount of hydraulic oil used regularly to prevent the hydraulic system from being affected by the low oil level.
Hydraulic oil contamination or oil quality is unqualified
Cause analysis:
Hydraulic oil contains impurities, moisture or too many bubbles, which may increase the friction inside the cylinder, damage the seal, and prevent the oil from flowing smoothly, causing the hydraulic cylinder to lose normal action.
Solution:
Check the quality of the hydraulic oil. If the oil is found to be contaminated or deteriorated, replace the hydraulic oil in time and clean the filter element in the hydraulic system.
Hydraulic pump failure or insufficient oil supply
Cause analysis:
The operation of the hydraulic cylinder depends on the pressure provided by the hydraulic pump. If the hydraulic pump fails or the output flow of the pump is insufficient, the system cannot provide enough hydraulic oil flow, resulting in the hydraulic cylinder not moving.
Solution:
Check the working status of the hydraulic pump, including the output flow and pressure of the pump, to ensure that the pump is working properly. If the pump fails, it needs to be repaired or replaced.
System leakage
Cause analysis:
If there is a leak in the hydraulic system, the hydraulic oil will be lost, resulting in insufficient system pressure, which will not provide enough power to the hydraulic cylinder, resulting in no action. Leakage points usually appear in pipes, valves, cylinder joints or sealing parts.
Solution:
Check all pipes, joints, valves and cylinder seals in the system for oil leaks. Repair the leaks to ensure that the system is well sealed.
Faulty or stuck control valve
Cause analysis:
Faulty or stuck valves that control the flow of hydraulic oil will block the flow of hydraulic oil and prevent it from entering the hydraulic cylinder normally, making the cylinder unable to move.
Solution:
Check whether the hydraulic control valve is working properly. If the valve is stuck, blocked or damaged, it should be cleaned, repaired or replaced.
Cavitation
Cause analysis:
If cavitation occurs in the hydraulic system, bubbles will affect the normal flow of hydraulic oil, causing the cylinder to not get enough hydraulic oil for movement. This usually happens when the pressure of the hydraulic system is too low or the hydraulic oil quality is poor.
Solution:
Remove bubbles from the system, check the quality of the hydraulic oil, ensure that the oil is clean, and avoid moisture and air from entering the system. Adjust the working pressure of the system to ensure that the cylinder can operate normally.
Hydraulic cylinder is stuck or damaged inside
Cause analysis:
If there is severe wear, jamming or piston rod damage inside the hydraulic cylinder, the movement inside the cylinder will be hindered, causing the hydraulic cylinder to fail to move.
Solution:
Check the inside of the cylinder, especially the piston and piston rod for jamming, scratches or damage. If damaged, repair or replace the damaged parts.
System pressure is too low or too high
Cause analysis:
If the pressure of the hydraulic system is too low, the cylinder cannot generate enough thrust for operation; if the pressure is too high, it may cause damage to the cylinder and other components.
Solution:
Use a pressure gauge to check the working pressure of the hydraulic system to ensure that the pressure is within the design range. If the system pressure is too low, check the pump and valve; if the pressure is too high, check the pressure regulating valve or safety valve.
Operating system control failure
Cause analysis:
If the control system of the hydraulic cylinder (such as PLC, sensor, button, etc.) fails, the signal may not be transmitted correctly and the hydraulic cylinder cannot be started.
Solution:
Check the electrical part of the control system to ensure that the control signal is normal. Check whether sensors, switches, relays and other components are working properly.

2. How to troubleshoot the failure of marine hydraulic cylinders not moving
Check the oil level and oil quality:
First check whether the oil level of the hydraulic oil is normal and ensure that the oil is clean. If the oil level is low or the oil quality is unqualified, the hydraulic oil should be replenished or replaced in time.
Check the hydraulic pump:
Check the output flow and pressure of the hydraulic pump to ensure that it is working properly. If the hydraulic pump fails, it should be repaired or replaced.
Check system leakage:
Carefully check all pipes, joints, valves, etc. in the system to ensure that there is no leakage. If a leak is found, it should be repaired in time.
Check the control valve:
Ensure that the control valve of the hydraulic system is working properly, check for sticking, blockage or damage, and clean or replace it if necessary.
Exclude cavitation:
If there are bubbles in the system, the air should be removed through the exhaust valve to maintain the fluidity of the hydraulic oil. Ensure that the hydraulic oil is free of moisture and impurities to avoid cavitation.
Check the hydraulic cylinder:
Check whether the hydraulic cylinder is stuck, damaged or internally worn. If a problem is found, clean the cylinder or replace the damaged parts.
Check the pressure adjustment:
Use a pressure gauge to check the system pressure and ensure that it is within a reasonable range. If the pressure is not appropriate, check the pressure valve and safety valve, and adjust or replace them.
Check the electrical control system:
Check the electrical system that controls the hydraulic cylinder to ensure that the control signal and electrical components are working properly and eliminate electrical faults.

3. Summary
There are many reasons why the marine hydraulic cylinder does not move, which may be caused by hydraulic oil problems, oil pump failure, system leakage, control valve jamming, etc. By systematically checking each link of the hydraulic system, checking the oil level, oil quality, oil pump, control valve and the condition of the hydraulic cylinder itself, the root cause of the problem can be effectively found and solved in time. Regular maintenance and inspection of the working status of the hydraulic system can effectively prevent the problem of hydraulic cylinder failure and ensure the normal operation and safety of ship equipment.