COMPLETE CATALOGUE Piston seals GKD 23 Items

The Hunger compact slide ring seal type GKD is used to seal and guide pistons on double-acting hydraulic cylinders. In standard form it is suitable for use with all mineral oils. The GKD consists of 4 parts, an elastic inner ring of PUR, a slide ring of abrasion-resistant PTFE-Bronze compound and two bearing rings of a pressure-resistant POM-PTFE-Bronze compound. The Hunger bearing rings make contact with the cylinder wall; there is no metallic contact between the piston and the cylinder body. The internal elastic ring energises the slide ring to press it against the cylinder wall providing a sealing function at zero pressure. The onset of pressure compresses the elastic ring increasing the radial forces acting on the slide ring, thereby increasing the sealing effect.

Like the slide ring, the two bearing rings also sit on the elastic ring. The pressure-induced compression of the internal ring forces the two bearing rings, and the slide ring, against the cylinder wall so that there is zero clearance between bearing rings and cylinder wall. Even if the cylinder tube expands under pressure, the seal will adapt to the radial deformation maintaining both zero gap and the sealing function. When combined with a surface finish of Ra 0.3 - 0.5 µm on the cylinder tube, minimum friction is achieved. The seal has an excellent efficiency with no stick-slip effect due to stiction.