Hydraulic clamping in the hydraulic system generally means that when the valve core stops moving for a period of time (about 2 ~ 5mm), great resistance is generated, making it very difficult for the valve core to move again. This phenomenon is easy to increase the wear of the slide valve, reduce the service life of the components, and cause adverse consequences for the operation of the system.
(1) Hydraulic clamping caused by radial force imbalance
The imbalance of radial hydraulic pressure caused by geometric error and coaxiality change of valve core and valve hole is the main reason for hydraulic clamping.
(2) Clamping caused by the adsorption of polar molecules in oil
After hydraulic clamping, the phenomenon of hydraulic clamping will not disappear until it lasts for a long time due to the adsorption of polar molecules in the oil.
(3) Hydraulic clamping caused by impurity wedging clearance
Impurities in the oil wedging into the gap will also form a hydraulic clamping.
Measures to prevent hydraulic clamping: open an annular balance groove, also known as uniform groove, on the valve core to reduce the radial unbalanced force; Strictly adjust the manufacturing accuracy of valve core and valve hole, and the matching clearance shall be reasonable. If it is too small, the leakage will increase. If it is too small, the valve core will be stuck due to thermal expansion when the temperature is too high; Precision filter the oil to ensure the cleanliness of the oil.
