Sealing Products

Hydraulic Seals

Wiper, rod, piston, and guide seals for hydraulic cylinders and valves — custom-machined to your exact bore and operating conditions.

Overview

Heavy-duty hydraulic sealing for trouble-free operations

Hydraulic seals are the components that make hydraulic cylinders, pumps, and valves function reliably. Without them, the pressure energy that drives construction equipment, presses, agricultural machinery, and aerospace actuators dissipates as leakage — and a leaking hydraulic system is both a safety hazard and a maintenance cost center.

A hydraulic cylinder requires a minimum of four sealing elements working together: a rod seal (primary pressure containment), a wiper seal (contamination exclusion), a piston seal (differential pressure), and a guide ring (load bearing and alignment). Getting the profile and material wrong on any one of them compromises the entire assembly.

We supply hydraulic seals individually and in complete kits, in all standard profiles and non-standard dimensions. Custom machining is available for unusual bore sizes, modified profiles, or materials suited to extreme service conditions.

Contamination is the primary failure cause: Over 70% of hydraulic seal failures trace back to contamination entering through a worn or undersized wiper seal. If you're replacing rod seals repeatedly, check the wiper first — it's the first line of defense.

Design Reference

Hydraulic seal profiles and functions

Four-position cylinder seal configuration

Each position in a hydraulic cylinder has a different mechanical requirement. The profiles are not interchangeable — substituting a piston seal in a rod position, or vice versa, leads to immediate failure.

Position	Function	Common Profiles
Rod seal	Primary pressure containment on the rod side. Prevents hydraulic fluid from exiting past the rod during extension and retraction.	U-cup (single-acting), Stepseal, loaded lip seal. Asymmetric profiles designed for one-way pressure loading.
Wiper seal (scraper)	Removes contamination (dirt, water, abrasive particles) from the rod on the return stroke. Protects the rod seal from abrasive damage.	Single-lip wiper, double-lip wiper, metal-cased wiper for aggressive environments.
Piston seal	Seals between the piston and the cylinder bore. Must hold differential pressure from both sides in double-acting cylinders.	U-cup (double-acting), T-seal (with backup rings), cup packing. Symmetric profiles for bidirectional loading.
Guide ring / wear ring	Absorbs side loads and prevents metal-to-metal contact between rod/piston and bore. Not a pressure seal.	Bronze-filled PTFE, phenolic resin, PEEK. Width and clearance selected for the side load.

Materials

Hydraulic seal materials

Polyurethane (PU)

–30°C to +100°C

The standard material for hydraulic U-cups and wipers. Excellent abrasion resistance, high tensile strength, good extrusion resistance. Best choice for mineral hydraulic oils.

NBR (Nitrile)

–40°C to +100°C

Mineral oils, hydraulic fluids, water-glycol. Lower abrasion resistance than PU — used where chemical compatibility or low temperature is the primary constraint.

FKM (Viton®)

–20°C to +200°C

Synthetic hydraulic fluids (phosphate ester, fire-resistant), high-temperature systems, aggressive chemical environments. Higher cost — specify only when NBR or PU is incompatible.

PTFE Composite

–60°C to +220°C

Low-friction sealing for servo cylinders and precision actuators. Spring-energized or elastomer-energized. Best dynamic performance, widest temperature range.

Need hydraulic seals or a complete cylinder kit?

Give us the bore diameter, rod diameter, cylinder stroke, operating pressure, and fluid — we'll specify the complete seal configuration and supply it as individual seals or a full kit.

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