TECHNICAL SUPPORT
Published 2026-03-21
Many people have encountered such troubles when using hydraulicservos: theservos move suddenly fast and slowly, or simply have no power, or even get stuck one after another. Eighty percent of this is a problem with the pressure regulation. The pressure of the hydraulic steering gear is like the blood pressure of the human body. If it is too high, it will easily "explode blood vessels"; if it is too low, it will "insufficient blood supply" and the movement will be dull. To make it work stably and reliably, mastering the correct pressure adjustment method is key. Let’s talk about this today and help you get it done step by step.
The pressure of the hydraulic steering gear is unstable, often because air is mixed into the system. After the air is compressed, it will cause the pressure gauge pointer to jump back and forth, and the steering gear will also move softly. It's like when there is air in the straw when you drink a drink, you suck it in and out and you can't drink it at all. It is also possible that the oil is too dirty, blocking the small holes in the valve core, causing the valve core to get stuck, and the pressure will naturally jump.
Another common cause is fatigue in the relief valve spring. As the spring becomes less elastic after being used for a long time, the set pressure will slowly drift. You may have just adjusted it, but then it changes again two days later. Therefore, if you find that the pressure is unstable, don't rush to make a hard adjustment. First check whether the oil is emulsified or black, drain the air, and replace the filter element, which can often solve most of the problems.
It is not difficult to adjust the pressure. The key is to find the regulating valve. There is an adjustment screw with a lock nut on most hydraulicservos, which is the adjustment mechanism of the relief valve. If you first loosen the lock nut and then turn the screw clockwise, the pressure will increase; if you turn it counterclockwise, the pressure will decrease. Note that it must be adjusted when the servo is running. The number adjusted statically is not accurate.
Be patient when adjusting and do it bit by bit. Don't turn it half a turn as soon as it comes up, turn it a quarter turn at a time, and then watch the pressure gauge reading and wait until it stabilizes before continuing. Why so slow? Because the hydraulic system has a response time, if you tighten it too quickly, it will easily overshoot and increase the pressure to a high level instantly, which may damage the seal. It's safest to take your time.
This depends on your actual working conditions. If you find that the servo cannot carry the load, has weak movement, or cannot turn in place, then you need to increase the pressure a little and "strengthen" it. However, it should be noted that the pressure cannot exceed the maximum working pressure calibrated by the equipment, otherwise the life of the pump and valve will be shortened, or the pipe may burst. Generally, it is safest to operate at 80%-90% of the rated pressure.
On the other hand, if the servo moves very suddenly, "bangs" as soon as it is started, or the system is abnormally hot, it means that the pressure may be too high and needs to be lowered. Too high pressure not only wastes energy, but also causes the oil temperature to rise rapidly. Once the oil temperature is high, the seals will easily age and leak oil. So don’t blindly pursue high pressure, just enough is enough.
Don't forget to screw back the lock nut on the regulating valve. Many people leave after adjusting the pressure. The nut is not tightened. When the machine vibrates, the adjusting screw slowly moves away and the pressure changes accordingly. Therefore, after adjusting, be sure to hold the adjusting screw with one hand and tighten the locking nut with the other hand, so that the value you set can be locked.
Another little tip: If you are using a control valve with a handwheel, use the handwheel when adjusting, rather than using a wrench. The handwheel is designed for you to use. It is easy to damage the threads with a wrench, and then you will not be able to adjust it even if you want to. If the handwheel is particularly tight, you can first check to see if the locking nut has been loosened. Don't force it.
The first step is to power on the device and let the servo run without load for a few minutes to allow the oil temperature to rise to normal operating temperature. Because the viscosity of cold oil and hot oil are different, pressure readings will be skewed. The second step is to find the adjusting screw of the relief valve and loosen the locking nut. The third step is to slowly turn the screw while staring at the pressure gauge to allow the pressure to reach the value you need.
Step 4: After the pressure stabilizes, keep the screw still and tighten the locking nut. The fifth step is to let the servo run with load for a few laps and observe whether the pressure can remain stable when the load changes. If you find large pressure fluctuations, you need to check whether there is air in the accumulator or oil circuit. With this set, it's basically done.
After completing the adjustment, don't rush to call it a day. You have to let the servo run under actual working conditions. For example, let it perform several cyclic actions in succession to see if the pressure gauge can respond quickly during the action and whether the pressure will drop seriously. If the pressure drops significantly during the action, it means that the system flow may not be enough, and light adjustment of the relief valve cannot solve the problem.
Also check the oil temperature. After adjusting the pressure, run it for half an hour and touch the fuel tank or valve body with your hand. If it feels too hot to touch, it means the pressure is adjusted too high or there is a problem with the system's heat dissipation. The normal oil temperature should be around 50-60 degrees, warm and warm is the ideal state. If everything is normal, congratulations, the pressure is adjusted.
What is the most troublesome problem you have encountered when adjusting the pressure of the hydraulic steering gear? Is it that the pressure is not adjusted correctly or that it cannot be locked? Welcome to leave a message in the comment area, let's communicate together, maybe your experience can help more people. If you find it useful, please give it a like and share it with friends who need it.
Update Time：2026-03-21
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