[52] Slide principle
This illustration shows the
principle of a longitudinal slide valve. In order to allow the
piston to move, it has a certain clearance and floats in
hydraulic fluids. Ring grooves ensure an even film of oil and
thus pressure equilibrium. The piston can thus be moved with
minimal frictional losses.
This type of valve cannot provide a perfect seal, which means that there is always a certain oil leakage.