GRN 20x28x4 NBR TC - Double Lip Rotary Shaft Oil Seal

GRN 20x28x4 NBR TC - Double Lip Rotary Shaft Oil Seal

GRN 20x28x4 NBR TC is a double lip radial shaft oil seal designed for a 20 mm shaft, a 28 mm housing bore and an installation width of 4 mm. Manufactured from nitrile butadiene rubber (NBR), it features a spring-loaded primary sealing lip, an additional dust exclusion lip and a rubber-covered outer diameter. The TC profile is designed to retain lubricants and reduce contamination in rotating shaft assemblies.

Technical Specifications - GRN 20x28x4 NBR TC

The maximum operating temperature, permissible shaft speed, pressure capability and dimensional tolerances must be confirmed for the specific GRN seal version.

General NBR material properties should not be interpreted as guaranteed operating limits for the finished seal.

What Does GRN 20x28x4 NBR TC Mean?

20 - Nominal Shaft Diameter

The first dimension identifies the nominal shaft diameter for which the seal is designed.

d = 20 mm

This is not necessarily the free-state diameter of the sealing lip. The lip geometry is designed to provide controlled contact pressure against the shaft.

28 - Nominal Housing Bore Diameter

The second dimension identifies the nominal outside diameter of the seal.

D = 28 mm

This corresponds to the nominal housing bore diameter required for installation.

4 - Nominal Seal Width

The third dimension identifies the axial width of the seal.

B = 4 mm

The narrow 4 mm design is relevant where installation space is limited.

NBR - Nitrile Butadiene Rubber

NBR is a synthetic elastomer commonly used in rotary shaft seals operating with mineral oils and lubricating greases.

Actual chemical compatibility depends on the fluid composition, temperature and specific rubber compound.

TC - Double Lip Seal Profile

The TC designation identifies a rotary shaft seal construction featuring:

• A spring-loaded primary sealing lip.

• An additional dust exclusion lip.

• A rubber-covered outside diameter.

• An internal metal reinforcing case.

The additional lip provides a secondary barrier against external contamination.

GRN - Product Brand

GRN identifies the brand of the sealing component.

For accurate product selection, the complete dimensions, material and TC profile should be specified.

Construction of the GRN Double Lip Oil Seal

The GRN 20x28x4 NBR TC seal consists of several functional components.

Primary Sealing Lip

The primary sealing lip operates in contact with the rotating shaft.

Its function is to retain lubricant within the sealed mechanical assembly.

The lip geometry provides controlled contact with the shaft surface.

Garter Spring

A circumferential garter spring supports the contact force of the primary sealing lip.

This helps maintain sealing contact during operation as the elastomer responds to mechanical and thermal conditions.

Secondary Dust Lip

The additional lip is normally positioned on the external side of the sealing arrangement.

Its function is to reduce the ingress of dust and small contaminants toward the primary sealing lip.

The dust lip does not make the seal suitable for pressure sealing or continuous immersion.

Internal Metal Case

The reinforcing metal case helps maintain the seal's shape and dimensional stability during installation and operation.

Rubber-Covered Outer Diameter

The NBR-covered outer surface contacts the housing bore and contributes to static sealing between the seal and the housing.

How Does the TC Oil Seal Work?

The GRN 20x28x4 TC seal operates through controlled contact between the primary elastomeric lip and the rotating shaft surface.

The garter spring contributes to the radial contact force.

A suitable lubricating film between the lip and shaft is important for limiting friction and wear.

The secondary dust lip helps protect the main sealing interface from external contamination.

Sealing performance depends on:

• Shaft diameter and dimensional tolerances.

• Shaft surface finish.

• Shaft runout and eccentricity.

• Housing bore dimensions.

• Installation alignment.

• Rotational speed.

• Lubrication.

• Operating temperature.

• Fluid compatibility.

• External contamination.

Incorrect installation or unsuitable shaft surface conditions can cause leakage and premature seal wear.

Why Choose a Double Lip TC Profile?

Compared with a single lip design, a TC oil seal incorporates an additional dust exclusion lip.

This provides an extra barrier in applications where the shaft area may be exposed to:

• Industrial dust.

• Airborne particles.

• General dirt.

• Small solid contaminants.

• Contaminated operating environments.

The secondary lip helps protect the primary sealing contact area.

However, a double lip seal is not automatically suitable for every operating environment.

It does not provide unlimited protection against pressurized water, abrasive slurry or continuous immersion.

NBR Material - Properties and Limitations

Nitrile butadiene rubber is widely used in industrial shaft sealing applications.

Its principal advantage is compatibility with many mineral oils and lubricating greases.

The material also provides the elasticity required for continuous contact between the sealing lip and the rotating shaft.

Typical Compatible Media

Depending on the specific compound and operating conditions, NBR may be suitable for:

• Mineral-based lubricating oils.

• Many mineral-based gear oils.

• Industrial greases.

• Selected technical operating fluids.

Material Limitations

NBR is not universally resistant to all chemicals.

Compatibility must be separately verified for:

• Aggressive solvents.

• Certain synthetic fluids.

• Ozone exposure.

• Hot water.

• Steam.

• Strong oxidizing chemicals.

• Elevated-temperature applications.

For applications requiring greater temperature or chemical resistance, alternative materials such as FKM may be more appropriate.

GRN TC Double Lip vs Single Lip Oil Seals

The presence of an additional lip does not automatically make the TC profile preferable in every application.

Before replacing a single lip seal with a double lip version, verify the available installation space, lubrication conditions and machine requirements.

GRN 20x28x4 TC vs Other Seal Dimensions

The dimensions of a rotary shaft seal must match the shaft and housing arrangement.

These dimensions are not automatically interchangeable.

Even a 1 mm difference in width may prevent correct installation or interfere with adjacent components.

Selection and Interchangeability

Before ordering GRN 20x28x4 NBR TC, verify:

1. Nominal shaft diameter of 20 mm.

2. Nominal housing bore diameter of 28 mm.

3. Available installation width of 4 mm.

4. Required TC double lip profile.

5. NBR material compatibility.

6. Presence of the spring-loaded primary lip.

7. Requirement for an additional dust lip.

8. Operating fluid.

9. Operating temperature.

10. Shaft rotational speed.

11. Shaft surface finish.

12. Shaft runout and eccentricity.

13. Housing bore condition.

14. Installation direction.

15. External contamination conditions.

Identical dimensions of 20x28x4 mm do not guarantee complete interchangeability.

Seals may differ in elastomer material, lip geometry, spring design, outer diameter construction and operating capabilities.

Typical Applications

TC radial shaft oil seals are used in appropriately designed rotating shaft assemblies, including:

• Mechanical gearboxes.

• Industrial drive systems.

• Rotating shaft mechanisms.

• Oil-lubricated housings.

• Industrial machinery.

• Equipment requiring dust exclusion.

• Auxiliary mechanical drives.

• Lubricated rotating assemblies.

These are typical applications for this seal design, not confirmed OEM applications for the specific GRN 20x28x4 product.

Installation and Operating Recommendations

Inspect the Shaft

Before installation, check the shaft surface for:

• Scratches.

• Grooves.

• Corrosion.

• Sharp edges.

• Excessive wear.

Damage in the sealing contact area can cause leakage and accelerated lip wear.

Clean the Housing Bore

Remove contamination, metal particles and remnants of the previous seal.

Check that the housing bore is free from damage.

Lubricate the Primary Lip

Before installation, apply a suitable lubricant compatible with NBR and the operating fluid.

Avoid dry startup of the primary sealing interface.

Protect the Sealing Lips

When passing the seal over shaft shoulders, keyways or sharp edges, use appropriate installation protection.

Apply Mounting Force Correctly

Press the seal evenly into the housing using a suitable installation tool.

Avoid direct impact on the sealing lips or garter spring.

Check Installation Direction

In a conventional oil-retaining arrangement, the spring-loaded primary sealing lip normally faces the lubricant being retained.

The final installation direction must follow the equipment design.

Common Causes of Oil Seal Failure

Incorrect Seal Dimensions

An unsuitable shaft diameter, housing diameter or seal width may prevent proper sealing.

Shaft Surface Damage

Grooves or scratches in the lip contact area may create leakage paths.

Dry Running

Insufficient lubrication can increase friction and accelerate lip wear.

Excessive Shaft Runout

Excessive shaft movement can prevent the sealing lip from maintaining consistent contact.

Incorrect Material Selection

An incompatible fluid may cause elastomer swelling, hardening or deterioration.

Installation Damage

Twisting, cutting or deforming the lip during installation may cause immediate or premature leakage.

Alternative Designations and Reference Terms

The product may also be identified using the following designation formats:

• GRN 20x28x4 NBR TC

• 20x28x4 TC GRN

• GRN TC 20x28x4

• 20x28x4 NBR oil seal

• 20x28x4 double lip oil seal

• Rotary shaft seal 20x28x4 NBR

• Radial shaft seal 20x28x4 TC

• Shaft sealing ring 20x28x4 NBR

• Oil seal 20x28x4 TC NBR

These are product identification and search reference formats, not confirmed OEM numbers or approved cross-references to other manufacturers.

Frequently Asked Questions

What are the dimensions of the GRN 20x28x4 TC oil seal?

It is designed for a nominal shaft diameter of 20 mm, a housing bore diameter of 28 mm and an axial installation width of 4 mm.

What does TC mean on an oil seal?

TC identifies a double lip rotary shaft seal with a spring-loaded primary sealing lip, an additional dust exclusion lip and a rubber-covered outer diameter.

Does the GRN 20x28x4 TC seal have a spring?

Yes. The specified design features a garter spring supporting the primary sealing lip.

Is NBR suitable for oil?

NBR is commonly used with many mineral oils and lubricating greases. Compatibility must still be checked for the actual fluid and operating temperature.

Is a TC double lip seal better than a single lip seal?

The additional lip provides dust exclusion, but the TC design is not necessarily the best choice for every application.

Can a 20x28x5 seal replace a 20x28x4 seal?

Not without verifying the installation space and housing geometry. The additional 1 mm of width may prevent proper mounting.

Which direction should the oil seal face?

In a conventional oil-retaining arrangement, the spring-loaded primary lip normally faces the oil being retained. Always follow the machine manufacturer's installation requirements.

Is this oil seal suitable for pressurized applications?

Pressure capability must be confirmed for the specific seal. Standard radial shaft oil seals are generally intended for applications with low differential pressure.

GRN 20x28x4 NBR TC - Key Technical Information

GRN 20x28x4 NBR TC is a double lip radial shaft oil seal with nominal dimensions of 20x28x4 mm. Manufactured from nitrile butadiene rubber, it features a spring-loaded primary sealing lip, an additional dust exclusion lip and a rubber-covered outer diameter. It is designed to retain lubricants and reduce contamination in appropriately engineered rotating shaft assemblies.

GRN Rotary Shaft Oil Seals at simmering.pl

simmering.pl supplies GRN rotary shaft oil seals, NBR and FKM sealing components, O-rings and other industrial sealing products for machine manufacturers, technical service providers and maintenance departments.

For accurate identification, specify the complete designation GRN 20x28x4 NBR TC, including the nominal dimensions, elastomer material and double lip construction.

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