Abstract: An unlockable non-return valve reduces the tendency of the poppet piston to jam by providing a first insert that has a guide diameter for the poppet piston over just a short section of its end side facing the piston collar, and wherein a supporting ring is arranged axially between the high-pressure seal and the first insert in a receiving element, the diameter of which is substantially smaller than the outside diameters of the inserts, the supporting ring likewise being produced from a metallic material having good sliding properties and being produced with a narrow clearance from the end section of the poppet piston and with a large radial clearance from the receiving element.

Abstract: The invention relates to an unlockable non-return valve which is intended to be used for very high system pressures, and to a valve housing having a continuous receiving bore located on a valve axis, a poppet piston which can be acted upon at a piston collar by a control pressure in order to unlock a closing element and, on both sides of the piston collar, is guided on end sections of at least approximately identical diameters in the direction of the valve axis. Two inserts are placed into the receiving bore on each side of the piston collar, into which the poppet piston dips with an end section, the end section being guided in a first insert which is close to the piston collar and is manufactured from a metallic material having good sliding properties, and a second insert following the first insert has a high-pressure seal which bears radially against the end section of the poppet piston and is supported axially by the first insert.