Rod seals are primarily used in pneumatic and hydraulic cylinders and are tasked with sealing the cylinder rod during movements towards inside or outside. The aim is to prevent leakage of the working medium under pressure from the cylinder. Maximum sealing efficiency in cylinder sealing systems is achieved by combining two rod seals.
One of these, the so-called primary seal, faces the working space of the cylinder and reliably seals against the high operating pressure inside the cylinder. A secondary, rod seal placed behind, takes over the main sealing function. First of all, it is designed to reduce the remaining oil film on the rod to a minimum during its extension. For this task it is preferable to use gaskets made of polyurethane. With their defined sealing edge, they ensure a fine-tuned clearance of the medium, guaranteeing the the leak tightness of the cylinder toward the outside.