Hydraulic clamping in the hydraulic system generally means that when the spool stops moving for a period of time (approximately 2 ~ 5mm), it generates a lot of resistance, making it difficult to re-spool. This phenomenon is likely to increase the wear of the spool valve, reduce the service life of the components, and at the same time cause adverse effects on the system operation.
(1) Hydraulic clamping caused by unbalanced radial force
The geometrical error of the spool and valve hole and the change in coaxiality cause the imbalance of the radial hydraulic pressure, which is the main reason for the hydraulic clamping.
(2) Seizure caused by the adsorption of polar molecules in oil
After hydraulic clamping, due to the adsorption of polar molecules in the oil, the hydraulic clamping phenomenon will disappear after a long time.
(3) Hydraulic clamping caused by impurity wedge gap
Wedges of impurities in the oil will also form hydraulic clamping.
Measures to prevent hydraulic clamping: Open an annular balance groove on the spool, also known as a uniform groove, to reduce the radial unbalanced force; strictly adjust the manufacturing accuracy of the spool and the valve hole, the clearance should be reasonable, and excessive leakage will increase, If the temperature is too high, the valve core will be stuck due to thermal expansion; the oil is precisely filtered to ensure the cleanliness of the oil.
