TECHNICAL SUPPORT
Published 2026-03-02
Friends, have you ever encountered such a situation - the ship is driving smoothly on the vast sea, and suddenly the steering gear fails to work. It either responds slowly, half a beat slower than normal, or it simply gets stuck and stops moving. Under such circumstances, not to mention relying on the steering gear to control the ship to dock and unload cargo, even the safety of the ship during navigation has become a serious issue.
I have been engaged in maintenance work in a shipyard for more than ten years. During these long years, the most common thing I have seen is various problems with hydraulic steering gears. Today we are going to talk about this really troublesome topic. We will use easy-to-understand vernacular to explain in detail how to repair the hydraulic steering gear. I guarantee that you will have a good idea after listening to it.
️ First look at the oil pipe joint and sealing ring. Oil leakage from hydraulic steering gear is most likely due to aging of the O-ring or loose joint. Feel along the oil pipe and start where there are oil stains. The most bizarre case I have ever seen was when a sealing ring the size of a fingernail broke, causing the entire ship to be anchored for three days.
️ Check the fuel tank vent again. Many people don't know that a blocked vent will cause an imbalance in the pressure inside the fuel tank, and the oil will be squeezed out from the weakest seal. Unscrew the fuel tank cap and listen for a "chi" sound. If it does, it means the vent hole is blocked. Just use a thin wire to clear it.
1️⃣ The first step is to check the filter element. If the hydraulic oil is dirty, it is most likely to jam the valve core. Remove the oil return filter and take a look. If it is covered with iron filings and sludge, congratulations, you have found the root cause of the problem. Replace the filter element and replace it with new oil, 80% of the time the problem can be solved.
2️⃣ The second step is manual disc pump. Turn off the power and try to turn the oil pump coupling with a wrench. If it can't turn, it means the mechanical part is stuck; if it can turn but the rudder doesn't move, it means the oil line is clogged. In this way, the scope of the fault can be narrowed down in minutes, saving you the trouble of tearing it apart.
Eighty percent of the time it's because there's air in the oil. Do you hear any abnormal "clicking" sound when the steering gear is working, like boiling porridge bubbling? If so, it needs to be vented. Find the exhaust screw on the top of the oil cylinder, loosen it and turn the steering slowly until there are no air bubbles in the oil flowing out, then tighten it again.
It's also possible that the oil pump is worn. Use a simple way to judge: turn the rudder all the way and look at the pressure gauge reading. If the pressure does not reach 80% of the rated value, the pump clearance is too large. In this case, just changing the oil is useless. You have to disassemble the pump and grind the valve plate, or directly replace the pump with a new one.
First check whether the feedback lever is loose. Theservodeviation is often caused by the screws of the mechanical feedback lever being loose, causing the position detected by the sensor to not match the actual position. If you tighten the fixing screw of the feedback lever and re-calibrate the zero position, it will probably be fine.
First, adjust the synchronization valves of the cylinders on both sides again. It should be noted that some olderservos do not have automatic synchronization function. In this case, the running speed of the cylinders on both sides is inconsistent, and the rudder will drift. At this time, you need to find the adjusting bolt on the diverter valve, make slight adjustments while turning the rudder, and continue operating until the displacement scales of the two cylinders are consistent. This work requires a certain amount of patience, but once the adjustment is successful, it will bring a great sense of accomplishment.
After completing the above operations, carefully check whether the operating status of the steering gear is stable. Observe the response of the servo at different angles to ensure that the cylinders on both sides can operate accurately and synchronously. At the same time, pay attention to various parameters of the steering gear, such as oil pressure, oil temperature, etc., to see if they are within the normal range. Only through comprehensive and detailed inspection can the subsequent normal use of the steering gear be ensured, providing reliable guarantee for navigation and other related operations.
️ Avoid using a screwdriver to pry hard. When removing the end cover, it is easy to use a screwdriver to pry it off and make sure that the sealing groove is carved into a deep groove. Installing a new ring will be useless. The correct way is to knock it with a copper rod or pull it out with a special puller.
️ Avoid installing in the opposite direction. The sealing ring on the piston rod is directional. If it is installed upside down, it will not only leak oil, but also roughen the rod. Look at the lip of the sealing ring. The opening must be facing the direction of the pressure oil.
️ Avoid installing circles directly. Before installing the new ring, soak it in hydraulic oil and apply some butter in the groove to fix it. If you force it in directly, it will easily twist the sealing lip, and it will leak again within three days.
Test without load first. Disconnect the tiller connection and let the steering gear run without load. Check whether the cylinders on both sides expand and contract smoothly and whether the pressure is stable. After running without load for half an hour, there was no abnormality, and then the rudder blade was connected.
Perform the reload test again. The rudder needs to be rotated continuously between 35 degrees left and right for two hours. During this period, the temperature changes of the fuel tank should be closely observed. Under normal conditions, the temperature rise of the fuel tank should not exceed 40 degrees. Once this value is exceeded, it indicates that the system resistance is large or the cooling effect is poor.
In addition, the rudder turning time must be measured when the ship is in the deepest draft. The time from the rudder to 35 degrees on one side to 35 degrees on the other side cannot exceed 28 seconds. If it exceeds this time range, you must check whether there is a problem with the oil pump displacement.
In the final analysis, steering gear maintenance is not a mysterious matter. The key lies in the correct and reasonable thinking. You only need to follow this process to troubleshoot step by step, and nine times out of ten the fault will be solved by itself. However, I would like to remind you that if it involves the overhaul of the main oil pump and control valve group, it is best to seek technical support from the original manufacturer. Last time, a ship owner dismantled the main pump by himself, and when he put it back together, there were two extra springs, which almost completely damaged the steering gear and scrapped it.
After all, although steering gear repair may not seem difficult, there are many details involved. It is a good idea to troubleshoot according to the process, and most problems can be solved easily. But once key components such as the main oil pump and control valve group are overhauled, the professionalism of the original factory's technical support becomes particularly important. Just like the boat boss last time, he took apart the main pump by himself, but when he put it back, there were two extra springs, which almost caused a disaster and the steering gear was scrapped, so it is better to be cautious.
By the way, what's the weirdest steering gear failure you've ever encountered? How to fix it? Come and talk in the comment area so that everyone can learn more. If you find the article useful, please like it and share it with more sailing brothers. Let’s talk about it in the next issue!
Update Time：2026-03-02
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