Forklift PU Hydraulic Piston Seal – UN UHS Heavy Machinery Oil Seal

Forklift PU Hydraulic Piston Seal — UN / UHS Type, 12 Material Options

This PU (polyurethane) hydraulic piston seal is a standard-size UN/UHS-type seal designed for forklift heavy machinery hydraulic cylinders. The seal provides the primary piston-to-cylinder-bore sealing function — preventing hydraulic fluid from bypassing the piston and maintaining full lifting pressure. Available in 12 material compounds including NBR, HNBR, EPDM, Silicone, FKM/Viton, CR, PU, FFKM, AFLAS, FVMQ, PTFE, and ACR, each with specific temperature ranges and fluid compatibility profiles. The material selection determines seal performance — PU (blue) provides excellent wear resistance for high-cycle applications, FKM (brown/green/black) handles high-temperature hydraulic systems up to 200°C, and PTFE (white) offers the widest temperature range from -180°C to 260°C with outstanding chemical resistance.

This seal is manufactured to standard mold dimensions for UN and UHS piston seal profiles commonly used in forklift lift cylinders, tilt cylinders, and steering cylinders. The 30-90 Shore A hardness range allows selection of the optimal seal stiffness for the specific application — softer seals conform better to worn cylinder bores while harder seals provide longer service life in smooth, well-maintained cylinders. Complete material specifications include: NBR (-30°C to 100°C, mineral oil), HNBR (-20°C to 150°C, high-temperature oil), EPDM (-55°C to 150°C, glycol-based fluids), Silicone (-55°C to 205°C, extreme temperature), FKM (-20°C to 200°C, high-temperature oil/chemical), and PTFE (-180°C to 260°C, universal chemical resistance). Custom sizes and colors are available with OEM/ODM service.

Installation requires cylinder disassembly and careful cleaning of the seal groove. The piston seal must be installed with the sealing lip oriented toward the pressure side — incorrect orientation causes immediate seal failure and cylinder bypass. Lubricate the seal and cylinder bore with clean hydraulic fluid during assembly. Replace in pairs with the rod seal and wiper for a complete cylinder service. For related hydraulic seal kits and cylinder components, browse our Forklift Hydraulic System catalog.

Technical Specifications

Compatible Equipment

Seals are packaged 1000 pcs per PP bag in carton boxes. Standard freight delivery to major ports worldwide. For material recommendations or bulk orders, contact our team with your application requirements.