SKF
Piston Seals
SKF piston seals are dynamic seals mounted on the piston of a hydraulic cylinder, sealing the pressure chamber(s) and enabling the transfer of hydraulic energy into mechanical force. They are available in single-acting and double-acting configurations, typically in compact seal profiles combining a PTFE or polyurethane sealing element with an energising elastomer ring. The seal must handle high and variable pressure while maintaining low friction and drift-free holding. SKF piston seals are designed for cylinders in mobile hydraulics, machine tools, presses, and injection moulding machines. The product line includes standard metric and inch sizes, with materials optimised for mineral oil and fire-resistant fluids. Selecting the correct piston seal improves cylinder volumetric efficiency and reduces internal leakage, directly impacting machine productivity and energy consumption.
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Double-Acting Profiles
Compact seal sets for bi-directional pressure sealing.
Low-Friction PTFE Options
Reduce break-away force and minimise stick-slip.
High Wear Resistance
Ecopur polyurethane compounds for long service under abrasive fluid conditions.
Easy Installation
Split and stretch designs simplify fitting onto one-piece pistons.
Wide Pressure Range
Seals rated from low-pressure holding to high-pressure working cycles.
Fluid Compatibility
Materials for HLP mineral oils, HFC water-glycols, and biodegradable fluids.
Single-Acting vs. Double-Acting Piston Seals
Single-acting piston seals seal in one direction only, used in simple plunger cylinders. Double-acting seals manage pressure on both sides of the piston, essential for differential and regenerative circuits. SKF supplies both types, with double-acting seals being the most common in modern double-rod cylinders.
Optimising Piston Seal Friction
Excessive piston seal friction wastes energy and generates heat, reducing overall machine efficiency. SKF’s low-friction PTFE seals with specific energiser profiles provide a near-hydrodynamic sliding film, cutting friction by up to 50% compared to standard compact seals, which is significant on large-diameter press cylinders.