Explanation of hydraulic valve sticking phenomenon

Sometimes the spool valve of the hydraulic system may become stuck, and this phenomenon, also known as mud blockage, can cause the hydraulic valve to become stuck. As for why the hydraulic valve is stuck, we will provide you with a detailed explanation below.

What is a stuck hydraulic valve

In fact, small particles reside between the hydraulic valve core and the valve body, increasing the friction force of the valve core movement. Damping viscosity reduces valve response, affects production, and increases maintenance costs.

Why does the hydraulic valve get stuck

Normally, the radial clearance between the valve core and valve body of a regular directional valve is between 3 and 13 μ Between m. However, in reality, it is difficult for the valve body to achieve excellent roundness and straightness (which is why servo valves and servo valve proportional valves install valve sleeves between the valve body and valve core - for high accuracy). Therefore, the radial clearance basically changes with the length of the valve core. This affects the friction of the valve core - of course, the cleanliness of the oil also affects the friction.

If the gap between the valve core and valve body is invaded by hard particles (such as sand) or soft particles (such as paint and sludge), more force is required to push the valve core. According to test data from Eaton Hydraulic, if the radial clearance of a valve core with a diameter of approximately 3.2mm (1/8 inch) operates at 210bar (3000PSI), approximately 136N (30 pounds) of thrust is required to move the valve core. But if the valve is operated by electromagnetic force, the electromagnetic force can provide at most about 45N (10 pounds) of thrust!

How to prevent hydraulic valve sticking:

Preventing hydraulic valve sticking is also very simple. Keep the oil clean, cool, and dry. 'Clean' means sufficient filtering system settings to prevent the invasion of hard particles. Cooling and drying "means that the operating temperature of the hydraulic system should not be too high, and water should not enter to avoid the invasion of soft particles such as sludge.

The above is the method for preventing hydraulic valve sticking and how to prevent it. In summary, hydraulic oil pollution is a potential and expensive cost.