GRN 25x47x7 NBR AO/TC Oil Seal - Double Lip Rotary Shaft Seal

GRN 25x47x7 NBR AO/TC Oil Seal is a double lip radial shaft seal designed for a 25 mm shaft, 47 mm housing bore and 7 mm installation width. The AO/TC configuration combines a spring-loaded primary sealing lip with an auxiliary dust lip. The primary lip helps retain lubricant inside the assembly, while the additional lip helps protect the main sealing interface against dust, dirt and external contamination. NBR nitrile rubber provides good resistance to many mineral oils and lubricating greases.

Technical Specifications - GRN 25x47x7 NBR AO/TC

Product Type: Radial shaft seal / oil seal / Simmerring
Brand: GRN
Design: AO / TC
Lip Design: Double lip
Dimensions: 25x47x7 mm
Material: NBR, nitrile butadiene rubber
Shaft Diameter d: 25 mm
Housing Bore D: 47 mm
Width B: 7 mm
Primary Sealing Lip: Yes
Auxiliary Dust Lip: Yes
Garter Spring: Yes
Outside Diameter: Rubber covered
Typical Temperature Range: approximately -30 to +100°C, depending on NBR compound, medium and operating conditions
Application: Dynamic sealing of rotating shafts

AO/TC Double Lip Design

The GRN 25x47x7 NBR AO/TC uses two functional lips with separate sealing and protective functions.

The primary sealing lip operates directly against the rotating shaft. A garter spring supports radial contact between the sealing edge and shaft surface, helping retain oil or grease inside the mechanical assembly.

The auxiliary dust lip is positioned toward the external environment. It provides an additional barrier that helps reduce the ingress of dust, dirt and other contaminants toward the primary sealing interface.

This double lip configuration is particularly useful where both lubricant retention and additional contamination protection are required.

Dimensions of the GRN 25x47x7 Oil Seal

The three principal installation dimensions are:

d: 25 mm
D: 47 mm
B: 7 mm

The seal is therefore designed for a 25 mm nominal shaft diameter, 47 mm housing bore and 7 mm installation width.

When selecting a replacement, all three dimensions should be checked together with the required material and lip configuration.

Matching the 25x47x7 mm dimensions alone does not guarantee complete interchangeability.

NBR Nitrile Butadiene Rubber

NBR, also known as Buna-N, is one of the most widely used elastomers in industrial sealing technology.

It provides good resistance to many:

• mineral oils
• lubricating greases
• compatible hydraulic oils
• technical lubricants
• oil-based industrial fluids

These characteristics make NBR suitable for numerous general-purpose radial shaft sealing applications.

Final material compatibility should always be checked against the specific fluid, additives, operating temperature and application conditions.

How the GRN 25x47x7 Shaft Seal Works

A radial shaft seal creates a dynamic sealing interface between a rotating shaft and stationary housing.

The spring-loaded primary lip remains in controlled contact with the 25 mm shaft surface. Its main function is to help retain lubricant inside the assembly and reduce leakage along the rotating shaft.

Effective sealing also depends on:

• shaft surface condition
• shaft finish
• rotational speed
• shaft alignment
• operating temperature
• lubricant type
• pressure conditions
• correct installation

A worn, scratched or corroded shaft surface can reduce sealing performance even when a correctly selected new oil seal is installed.

Auxiliary Dust Lip Protection

The second lip provides additional protection on the atmospheric side of the seal.

It helps limit the ingress of:

• dust
• dirt
• fine particles
• general external contamination

toward the primary sealing lip.

This helps protect the main sealing interface in machinery operating under normal industrial contamination conditions.

The auxiliary lip should not be considered a replacement for specialized sealing systems required in extremely contaminated environments.

Industrial Applications

The GRN 25x47x7 NBR AO/TC double lip oil seal can be used in appropriately designed:

• gearboxes
• speed reducers
• pumps
• electric motors
• mechanical drive systems
• industrial machinery
• agricultural machinery
• workshop equipment
• bearing arrangements
• rotating mechanical assemblies

The final application should always be evaluated according to operating speed, temperature, pressure, lubricant and environmental conditions.

GRN 25x47x7 for Gearboxes and Drives

The 25 mm shaft size makes this seal suitable for appropriately dimensioned mechanical drive assemblies.

In gearboxes and reducers, radial shaft seals are commonly positioned where rotating shafts pass through the housing. Their function is to help retain lubricant while allowing the shaft to rotate.

The additional dust lip can provide useful protection where the external section of the shaft is exposed to typical workshop or industrial contamination.

AO/TC vs Single Lip Oil Seal

The main difference between an AO/TC double lip seal and a typical single lip oil seal is the presence of the auxiliary dust lip.

A single lip design primarily performs the lubricant retention function.

The AO/TC configuration adds a second protective barrier between the surrounding environment and the primary sealing zone.

A single lip 25x47x7 seal should therefore not automatically be considered an equivalent replacement where an AO/TC double lip configuration is specified.

Selecting a GRN 25x47x7 Oil Seal

Before selecting a replacement, verify:

Shaft Diameter: 25 mm
Housing Bore: 47 mm
Width: 7 mm
Material: NBR
Design: AO / TC
Lip Configuration: Double lip
Primary Lip: Spring-loaded
Auxiliary Dust Lip: Yes
Operating Medium: Compatible with NBR
Operating Temperature: Suitable for the NBR compound
Shaft Speed: Appropriate for the application

Correct selection requires more than matching the three nominal dimensions.

Shaft Condition and Installation

Before installing the GRN 25x47x7 oil seal, inspect the shaft contact area for:

• wear grooves
• scratches
• corrosion
• contamination
• mechanical damage

Care should also be taken when passing the sealing lip over shaft edges, threads, splines or keyways.

Damage to the sealing edge during installation can cause leakage immediately or significantly reduce the service life of the seal.

Operational Advantages

Double lip AO/TC construction: combines lubricant retention with additional contamination protection.

NBR material: provides good resistance to many mineral oils and lubricating greases.

Spring-loaded primary lip: supports controlled contact with the rotating shaft.

Auxiliary dust lip: helps protect the primary sealing interface from external contaminants.

25x47x7 mm dimensions: provide clear installation geometry for replacement identification.

GRN identification: allows the product to be clearly recognized for purchasing, maintenance and warehouse replenishment.

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FAQ - GRN 25x47x7 NBR AO/TC

What are the dimensions of the GRN 25x47x7 oil seal?
The seal is designed for a 25 mm shaft and 47 mm housing bore, with an installation width of 7 mm.

Is GRN 25x47x7 AO/TC a double lip oil seal?
Yes. It has a spring-loaded primary sealing lip and an auxiliary dust protection lip.

What is the function of the second lip?
The auxiliary lip helps reduce the ingress of dust, dirt and other external contaminants toward the primary sealing interface.

Is NBR suitable for mineral oils?
Yes. NBR provides good resistance to many mineral oils and lubricating greases. Compatibility should still be verified for the specific operating fluid and temperature.

Is this oil seal designed for a 25 mm shaft?
Yes. The first dimension in 25x47x7 identifies the nominal shaft diameter of 25 mm.

Does the primary sealing lip have a spring?
Yes. A garter spring supports the primary lip and helps maintain controlled contact with the rotating shaft.

Can a single lip 25x47x7 seal replace the AO/TC version?
Not automatically. A single lip design does not provide the same auxiliary dust protection as the AO/TC double lip configuration.

Are all 25x47x7 oil seals interchangeable?
No. Seals with identical dimensions may differ in material, lip geometry, construction and intended operating conditions.

Frequently Asked Questions by Engineers

Is the 25x47x7 dimension sufficient to select a replacement seal?
No. Material, lip configuration, operating medium, temperature, shaft speed and application requirements should also be verified.

Which lip retains the lubricant?
The spring-loaded primary lip performs the main lubricant retention function. The auxiliary lip primarily provides contamination protection.

What should be checked on the shaft before installing a new oil seal?
Inspect the sealing contact area for wear grooves, corrosion, scratches and other surface damage that could affect sealing performance.

Can NBR be used with every type of oil?
No. NBR is compatible with many mineral oils and greases, but compatibility should be checked for the specific fluid, additives and operating temperature.

Why can a new oil seal leak on a worn shaft?
The sealing lip requires an appropriate contact surface. A wear groove, corrosion or surface damage can prevent the lip from maintaining the required sealing interface.