Hydraulic equipment depends on reliable sealing components to maintain pressure, prevent fluid leakage, protect internal components, and ensure stable operation. Hydraulic cylinders, pumps, valves, industrial actuators, and mobile machinery all require sealing solutions that can withstand pressure, movement, temperature, and contact with hydraulic fluids.

Among the most commonly used polymer sealing products are spring energized seals, Glyd rings, and Step Seals. These products are available in a wide range of standard sizes and material combinations, while customized versions can also be manufactured for special equipment.

Although these seals share some material characteristics, their structures and typical applications are different. Selecting the right seal requires an understanding of the sealing position, operating conditions, and equipment design.

Why Seals Are Important in Hydraulic Equipment

A hydraulic system converts fluid pressure into mechanical movement. Any uncontrolled leakage can reduce system efficiency and affect equipment performance.

Hydraulic seals perform several important functions:

• Prevent hydraulic fluid leakage
• Maintain system pressure
• Reduce contamination
• Protect moving components
• Reduce friction
• Improve equipment reliability
• Extend service intervals

A complete hydraulic cylinder may use several sealing components together, including piston seals, rod seals, wiper seals, guide rings, and buffer seals.

The correct combination depends on the cylinder design and operating conditions.

Spring Energized Seals

Spring energized seals are polymer sealing products that use a metal spring to maintain continuous sealing force.

A typical design consists of:

• PTFE or another engineered polymer sealing jacket
• Metal spring energizer
• Sealing lip or contact surface

The spring provides an initial sealing force and helps maintain contact between the sealing element and mating surface.

Features of Spring Energized Seals

Low Friction

PTFE-based sealing jackets offer very low friction.

This is useful in hydraulic equipment where excessive friction can increase:

• Energy consumption
• Heat generation
• Wear
• Starting resistance

Excellent Chemical Resistance

PTFE provides excellent resistance to many hydraulic fluids, chemicals, solvents, and aggressive media.

The exact compatibility depends on the PTFE formulation and working fluid.

Wide Temperature Capability

PTFE-based seals can operate over a broad temperature range when the polymer and spring materials are correctly selected.

Effective Low-Pressure Sealing

Unlike pressure-energized seals that depend primarily on system pressure, spring energized seals receive sealing force from the spring itself.

This can be beneficial during startup, shutdown, or low-pressure operation.

Spring Materials

Common spring materials may include corrosion-resistant stainless steels and other alloys.

The spring material should be selected according to:

• Temperature
• Chemical exposure
• Corrosion conditions
• Required spring force
• Service environment

Glyd Rings

Glyd rings are widely used as dynamic piston seals in hydraulic cylinders.

A typical Glyd ring consists of:

• PTFE or polymer sealing ring
• Elastomer O-ring energizer

The O-ring provides radial force, while the PTFE ring forms the main sliding sealing surface.

This design combines the elasticity of rubber with the low-friction characteristics of PTFE.

Features of Glyd Rings

Glyd rings provide several advantages for hydraulic applications.

Low Friction

The PTFE sealing ring provides low sliding friction, helping the piston move smoothly.

Good Wear Resistance

Filled PTFE compounds can provide improved wear resistance under repeated reciprocating movement.

Good Chemical Resistance

PTFE provides good resistance to many hydraulic fluids and industrial media.

Smooth Reciprocating Movement

Low friction can help reduce stick-slip and improve cylinder movement.

Compact Design

Glyd rings can provide effective piston sealing within relatively compact grooves.

Typical Hydraulic Applications

Glyd rings are commonly used in:

• Hydraulic cylinders
• Industrial actuators
• Mobile hydraulic equipment
• Machine tools
• Injection molding machinery
• Pressing equipment
• Automation systems

Step Seals

Step Seals are dynamic sealing products commonly used for hydraulic rod sealing.

A typical Step Seal consists of:

• Polymer sealing ring
• Elastomer energizer

The polymer element provides the primary sealing function, while the elastomer maintains contact with the moving rod.

Features of Step Seals

Step Seals are commonly selected for:

• Low friction
• Good wear resistance
• Dynamic rod sealing
• Compact installation
• Good pressure performance
• Long-term reciprocating movement

Their actual performance depends on the profile, material, pressure, temperature, surface finish, and installation dimensions.

Glyd Rings vs Step Seals

The most obvious difference between Glyd rings and Step Seals is their typical installation position.

The seal profile and manufacturer's technical specifications should always be checked before selecting a product.

Spring Energized Seals vs Glyd Rings and Step Seals

The main structural difference is the energizing mechanism.

Spring energized seals use a metal spring, while Glyd rings and Step Seals commonly use an elastomer energizer.

Spring energized seals are particularly useful where low pressure, temperature, chemical compatibility, or specialized sealing requirements are important.

Glyd rings and Step Seals are more commonly used as standard piston and rod sealing products in hydraulic cylinders.

Common Materials for Hydraulic Seals

Material selection has a major effect on seal performance.

PTFE

PTFE is widely used for hydraulic seals because of:

• Very low friction
• Excellent chemical resistance
• Good temperature resistance
• Good dimensional stability

Different fillers can improve mechanical and wear properties.

Common PTFE compounds include:

• Virgin PTFE
• Glass-filled PTFE
• Carbon-filled PTFE
• Graphite-filled PTFE
• Bronze-filled PTFE

NBR

NBR is widely used as an elastomer material because it provides:

• Good oil resistance
• Good elasticity
• Good mechanical properties
• Cost-effective performance

It is suitable for many general hydraulic applications.

FKM

FKM is commonly selected for more demanding applications requiring good resistance to:

• High temperatures
• Oils
• Fuels
• Many chemicals

Polyurethane

Polyurethane is widely used for hydraulic rod seals, piston seals, and wiper seals.

Its key advantages include:

• Excellent abrasion resistance
• Good tensile strength
• Good tear resistance
• Good dynamic performance

It is particularly suitable for demanding reciprocating applications.

Other Seals Used in Hydraulic Equipment

Spring energized seals, Glyd rings, and Step Seals are only part of a complete hydraulic sealing system.

Wiper Seals

Wiper seals prevent external contaminants from entering the cylinder.

They help protect internal components from:

• Dust
• Dirt
• Mud
• Water
• Metal particles

Polyurethane wipers are commonly used in heavy-duty hydraulic equipment because of their abrasion resistance.

Guide Rings

Guide rings support the piston or rod and reduce metal-to-metal contact.

They can help:

• Carry radial loads
• Protect the cylinder bore
• Improve alignment
• Reduce wear

PTFE bronze guide strips are one common solution where low friction and wear resistance are required.

Buffer Seals

Buffer seals can help manage pressure fluctuations and protect the primary rod seal.

They are often used in high-pressure hydraulic cylinders.

How to Select the Right Hydraulic Seal

Selecting a standard seal requires more than simply matching the nominal diameter.

1. Determine the Sealing Position

Identify whether the seal is used for:

• Piston sealing
• Rod sealing
• Rotary sealing
• Static sealing

This determines which profiles should be considered.

2. Check Pressure

Consider:

• Normal pressure
• Maximum pressure
• Pressure spikes
• Pressure cycles

The seal profile and extrusion clearance must be suitable for the application.

3. Check Temperature

Evaluate the complete operating temperature range.

Both the primary sealing material and energizer must remain suitable at the required temperatures.

4. Identify the Hydraulic Fluid

Common hydraulic media include:

• Mineral oil
• Water-based fluids
• Synthetic fluids
• Special hydraulic fluids

Material compatibility must be verified for the actual fluid.

5. Check Reciprocating Speed

Cylinder speed affects:

• Friction
• Heat generation
• Wear
• Service life

High-speed applications may require specialized PTFE compounds or seal profiles.

6. Check Groove Dimensions

Important dimensions include:

• Rod diameter
• Bore diameter
• Groove diameter
• Groove width
• Groove depth
• Extrusion clearance

Correct installation geometry is essential for reliable sealing.

7. Check Surface Finish

The rod and cylinder bore should have an appropriate surface finish.

A rough surface can accelerate seal wear, while an unsuitable surface condition can affect leakage and friction.

Standard Hydraulic Seals vs Custom Seals

Standard hydraulic seals are available in many common dimensions.

They provide several benefits:

• Easy replacement
• Lower cost
• Established profiles
• Shorter procurement cycles
• Wide availability

Standard products are particularly suitable for conventional hydraulic cylinders.

However, specialized equipment may require custom sealing components due to:

• Non-standard grooves
• Unusual dimensions
• High pressure
• High temperature
• Aggressive fluids
• Limited installation space

Custom seals can be manufactured according to:

• Technical drawings
• CAD files
• Physical samples
• OEM specifications
• Specific operating requirements

Precision Manufacturing of PTFE Hydraulic Seals

Precision machining is particularly useful for custom PTFE sealing components.

CNC machining can produce:

• Custom Glyd rings
• Custom Step Seals
• Spring energized seal jackets
• PTFE piston seals
• PTFE rod seals
• Special sealing rings

Important manufacturing factors include:

• Dimensional accuracy
• Profile geometry
• Surface finish
• Material consistency
• Groove compatibility

For small and medium production quantities or non-standard designs, CNC machining can provide flexibility without requiring dedicated tooling for every variation.

Typical Hydraulic Applications

Standard hydraulic sealing products are used in a wide range of equipment.

Construction Equipment

Excavators, loaders, cranes, and other heavy machinery require hydraulic cylinders capable of operating under high pressure and heavy loads.

Agricultural Equipment

Hydraulic cylinders used in agricultural machinery operate in environments with dust, mud, moisture, and temperature changes.

Industrial Machinery

Hydraulic presses, machine tools, injection molding machines, and industrial actuators use multiple sealing components.

Mobile Hydraulic Systems

Mobile equipment requires sealing systems capable of handling vibration, contamination, pressure fluctuations, and frequent movement.

Conclusion

Spring energized seals, Glyd rings, and Step Seals are important standard sealing solutions for hydraulic equipment, but each design serves a different purpose.

Spring energized seals use a metal spring to provide continuous sealing force and are particularly suitable for specialized applications requiring low friction, chemical resistance, broad temperature capability, or reliable low-pressure sealing.

Glyd rings are commonly used as piston seals, combining a polymer sealing ring with an elastomer O-ring energizer. Step Seals are commonly used as rod seals, providing low-friction dynamic sealing during reciprocating movement.

A reliable hydraulic sealing solution should also consider wiper seals, guide rings, buffer seals, and other components as part of the complete cylinder sealing system.

The right seal should be selected according to pressure, temperature, hydraulic fluid, movement speed, surface finish, groove dimensions, and material compatibility.

For conventional hydraulic equipment, standard-size seals provide an economical and convenient solution. For specialized equipment, manufacturers with precision PTFE machining capabilities can provide custom spring energized seals, Glyd rings, Step Seals, piston seals, rod seals, and other non-standard hydraulic sealing components according to drawings, samples, and OEM requirements.