A direct-acting shear seal type valve where the contact force between seat (4) and slide (12) is transferred to the relieving means (5) previously to and during a new positioning of the slide. In this way, the frictional power generated by the normal force on the contact faces (20) between seat (4) and slide (12), is reduced substantially. By using two double electromagnets (7 and 8), one achieves a large pushing power at the start of the stroke in order to overcome the remaining static friction; a large pushing power during the stroke in order to overcome the remaining sliding friction, and a large pushing power at the end of the stroke, when the seat and slide hole is in the process of being closed, for cutting loose pollution elements which, possibly, have got stuck in the opening.
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