Product range

Hydraulic Seals for Cylinders That Work Hard

Rod seals, piston seals, wipers, buffer seals, guide and wear rings and complete seal kits for hydraulic cylinders.

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Fig. — Hydraulic Seals · schematic, not to scale

Overview

About Hydraulic Seals

A hydraulic cylinder relies on a system of seals working together. Rod seals retain pressurised fluid at the gland, piston seals separate the two sides of the piston, wipers keep contamination out, buffer seals protect the rod seal from pressure peaks, and guide and wear rings carry side loads so that metal parts do not touch.

Sealing Technologies supplies each of these elements individually and as complete seal kits configured as one sealing system, for cylinders used in steel plants, cement plants, construction and mining machinery and general engineering. Share the cylinder details or the old seal, and our sales engineers will help identify a suitable replacement.

Sealing system

Where Each Seal Sits in a Hydraulic Cylinder

Each element has its own job. Together they retain pressure, exclude contamination and keep moving parts guided.

1Piston sealSeals the piston against the cylinder bore.
2Wear ringsKeep the piston centred and carry side load.
3Guide ringGuides the rod in the gland.
4Buffer sealAbsorbs pressure peaks ahead of the rod seal.
5Rod sealRetains fluid at the moving rod.
6Wiper sealKeeps dirt and moisture out.
7Static sealsSeal the joints between fixed parts.
+Seal kitsAll of the above, made up for one cylinder.

Fig. — Hydraulic cylinder sealing system · schematic, not to scale

Product range

Hydraulic Seals — Profiles and Specifications

Sizes and ratings are confirmed against your application. Where a value is not listed, it is available as per application requirement.

Rod Seals

Fitted in the cylinder gland to seal on the moving rod and prevent hydraulic fluid leaking out of the cylinder.

Seals dynamic rod surface
Single-acting lip designs
Works with buffer seal and wiper

Rod Diameter: Available as per application requirement.
Groove Dimensions: Available as per application requirement.
Material: Polyurethane, NBR, FKM, PTFE compounds — as per application
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Cylinder gland / rod end

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Piston Seals

Fitted on the piston to seal against the cylinder bore, so that pressure on one side moves the piston. Single- and double-acting designs.

Seals against cylinder bore
Single- or double-acting
Compact and multi-part designs

Bore Diameter: Available as per application requirement.
Groove Dimensions: Available as per application requirement.
Material: PTFE compounds, polyurethane, NBR — as per application
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Cylinder piston

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Wiper Seals

Scrape dirt, dust and moisture off the retracting rod so that contamination does not enter the cylinder.

Excludes external contamination
Protects rod seal and guide rings
Snap-in and metal-cased types

Rod Diameter: Available as per application requirement.
Groove Dimensions: Available as per application requirement.
Material: Polyurethane, NBR, FKM — as per application
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Cylinder gland, outermost position

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Buffer Seals

Positioned ahead of the rod seal to absorb pressure peaks and protect the rod seal in heavy-duty cylinders.

Protects rod seal from pressure spikes
Used in heavy-duty sealing systems
Often combined with a back-up ring

Rod Diameter: Available as per application requirement.
Groove Dimensions: Available as per application requirement.
Material: Polyurethane, PTFE compounds — as per application
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Heavy-duty cylinder glands

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Guide Rings

Guide the rod or piston and absorb side loads, preventing metal-to-metal contact between moving parts.

Carries radial side load
Prevents metal-to-metal contact
Cut-to-size strip or moulded rings

Rod Diameter: Available as per application requirement.
Groove Dimensions: Available as per application requirement.
Material: Filled PTFE, fabric-reinforced resin, engineering plastics
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Rod and piston guidance

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Wear Rings

Bearing elements that keep the piston centred in the bore and protect the seals and hardware from wear.

Keeps piston centred
Protects seals and bore
Various materials for load and speed

Bore Diameter: Available as per application requirement.
Groove Dimensions: Available as per application requirement.
Material: Filled PTFE, fabric-reinforced resin, engineering plastics
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Piston and rod bearing

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Static Seals

High-pressure O-rings and other close-tolerance static seals for cylinder heads, end caps, ports and stationary machinery joints.

High-pressure O-rings
Seals between non-moving parts
Wide range of materials

Size: Available as per application requirement.
Material: NBR, FKM, silicone, HNBR, PTFE — as per application
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Cylinder heads, end caps and ports

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Back-Up Rings

Extrusion protectors that support elastomer seals when fluid pressure is high.

Support O-rings and lip seals against extrusion
Used on the low-pressure side of the seal
PTFE and other materials as per application

Size: Available as per application requirement.
Material: PTFE and others — as per application
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: High-pressure static and dynamic seals

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Hydraulic Seal Kits

Complete sets of rod seals, piston seals, wipers, guide rings and static seals made up for a specific cylinder.

All seals for one cylinder together
Made up to drawing, size list or sample
Simplifies overhaul and stocking

Kit Contents: As per cylinder drawing, size list or sample
Material: As per application requirement
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Cylinder overhaul and maintenance

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Customized Hydraulic Sealing Solutions

Non-standard sizes and special profiles for large, old or imported cylinders, sourced to drawing or sample.

Large-diameter and non-standard seals
Sourced to drawing or sample
Material selected for the duty

Rod Diameter: Available as per application requirement.
Groove Dimensions: Available as per application requirement.
Material: As per application requirement
Temperature: Depending on compound, design and application.
Pressure: Depending on compound, design and application.
Application: Special and large cylinders

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Questions

Frequently Asked Questions

What is the difference between a rod seal and a piston seal?

A rod seal is fitted in the cylinder gland and seals on the moving rod to stop fluid leaking out of the cylinder. A piston seal is fitted on the piston and seals against the cylinder bore so that pressure on one side moves the piston.

Can you help identify a hydraulic seal without a part number?

Yes. Rod diameter, bore diameter, groove dimensions, the seal profile and a photograph or the old seal are usually enough for our engineers to identify a suitable replacement.

Do you supply complete hydraulic seal kits?

Yes. Seal kits are made up against the cylinder drawing, a list of seal sizes or the old seal set, so that all sealing elements for a cylinder overhaul arrive together.

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Need help selecting a seal from this range?

Share the seal size, a drawing or the operating conditions. Our sales engineers will help identify a suitable sealing solution and send you a quotation.

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