Hydraulic seals are a device that restricts the escape of fluid or the entrance of foreign materials in a hydraulic application such as a cylinder. Hydraulic Seals are designed for high pressure dynamic applications such as hydraulic cylinders. Hydraulic Seals are vital in machinery. Hydraulic Seals are critical in producing a way for fluid power to be converted to linear motion. Hydraulic Seals may be used for rotary and reciprocating motion.

Common hydraulic seals include: rod seals, piston seals, symmetrical seals, V-Rings, wipers, rotary shaft seals, wear rings, static seals, back-up rings, o-rings, buffer rings, u-cups, oil & grease seals, cast iron piston rings and gaskets. Hydraulic seals can be single or double acting. Single acting hydraulic seals are used for one axial direction only. Double acting hydraulic seals are used in both directions for a reciprocating motion. Hydraulic seals can be made of a variety of materials: Polyurethane, Nitrile, Viton, PTFE, Silicone, EPDM, POM, Nylon, bronze filled PTFE, Nickel filled PTFE, glass filled PTFE. Some hydraulic seals can be molded of fabric reinforced rubber or leather.