GRN 30x47x7 NBR AO Oil Seal - Double Lip Rotary Shaft Seal

GRN 30x47x7 NBR AO Oil Seal - Double Lip Rotary Shaft Seal

GRN 30x47x7 NBR AO Oil Seal is a double lip radial shaft seal designed for a 30 mm shaft, 47 mm housing bore and 7 mm installation width. The AO design combines a spring-loaded primary sealing lip with an auxiliary dust lip. The primary lip helps retain oil or grease inside the mechanical assembly, while the secondary 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 30x47x7 NBR AO

Product Type: Radial shaft seal / oil seal / Simmerring
Design: AO
Dimensions: 30x47x7 mm
Material: NBR - Nitrile Butadiene Rubber
Brand: GRN
Shaft Diameter d: 30 mm
Housing Bore D: 47 mm
Width B: 7 mm
Lip Design: Double lip
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, operating medium and service conditions
Application: Dynamic sealing of rotating shafts

AO Double Lip Design

The AO configuration incorporates two functional lips with different roles.

The primary sealing lip operates directly against the rotating shaft. A garter spring supports radial contact between the sealing edge and the shaft surface, helping retain lubricant inside the 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 arrangement is particularly useful where lubricant retention and additional protection against external contamination are required.

Dimensions of the GRN 30x47x7 Oil Seal

The three principal installation dimensions are:

d: 30 mm
D: 47 mm
B: 7 mm

The seal is therefore designed for a 30 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 NBR material and AO double lip configuration.

Matching the 30x47x7 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 rotary shaft sealing applications.

Final material compatibility depends on the specific operating fluid, additives, temperature and actual service conditions.

How the GRN 30x47x7 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 30 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 surface finish
• shaft alignment
• rotational speed
• operating temperature
• lubricant type
• pressure conditions
• correct installation

A worn, scratched or corroded shaft surface can reduce sealing performance even when the correct new oil seal has been installed.

Auxiliary Dust Lip Protection

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

It helps reduce the ingress of:

• dust
• dirt
• fine particles
• general external contamination

toward the primary sealing zone.

This additional barrier can be particularly useful where the exposed section of the shaft operates in an environment containing normal industrial or workshop contaminants.

GRN 30x47x7 for Gearboxes and Drive Systems

The 30x47x7 mm oil seal can be used in appropriately dimensioned gearbox, reducer and mechanical drive assemblies.

In these applications, a radial shaft seal is typically installed where a rotating shaft passes through the housing.

The primary lip helps retain lubricant inside the mechanism, while the auxiliary lip helps protect the sealing zone from contamination entering from the external environment.

Shaft condition should always be inspected when replacing an existing oil seal, particularly if a wear groove has developed in the sealing contact area.

Industrial Applications

The GRN 30x47x7 NBR AO double lip oil seal can be used in appropriately designed:

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

Final suitability should always be evaluated according to operating speed, temperature, pressure, lubricant and environmental conditions.

AO vs Single Lip Oil Seal

The AO design includes an auxiliary dust lip in addition to the primary sealing lip.

A typical single lip oil seal primarily performs the lubricant retention function.

The double lip AO configuration adds another protective barrier between the surrounding environment and the primary sealing interface.

A single lip 30x47x7 seal should therefore not automatically be considered an equivalent replacement where an AO double lip design is required.

How to Select a GRN 30x47x7 Oil Seal

Before selecting a replacement, verify:

Shaft Diameter: 30 mm
Housing Bore: 47 mm
Width: 7 mm
Material: NBR
Design: AO
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 consideration of both dimensional and operating requirements.

Shaft Surface and Installation

Before installing the GRN 30x47x7 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 threads, splines, keyways or sharp edges.

Damage to the sealing edge during installation can result in premature leakage even when the oil seal has been correctly selected.

Operational Advantages

Double lip AO 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 between the sealing edge and rotating shaft.

Auxiliary dust lip: helps protect the primary sealing interface against external contamination.

30x47x7 mm dimensions: provide clearly defined installation geometry for replacement identification.

GRN identification: supports precise product identification for purchasing, industrial maintenance, MRO and warehouse stock replenishment.

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FAQ - GRN 30x47x7 NBR AO

What are the dimensions of the GRN 30x47x7 oil seal?
The seal is designed for a 30 mm shaft and 47 mm housing bore, with an installation width of 7 mm.

Is the GRN 30x47x7 AO oil seal double lip?
Yes. It has a spring-loaded primary sealing lip and an auxiliary dust protection lip.

Is this oil seal designed for a 30 mm shaft?
Yes. The first dimension in 30x47x7 identifies the nominal shaft diameter of 30 mm.

What is the function of the auxiliary 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 and greases?
NBR provides good resistance to many mineral oils and lubricating greases. Compatibility should still be verified for the specific operating medium and temperature.

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

Are all 30x47x7 oil seals interchangeable?
No. Oil seals with identical dimensions may differ in material, lip configuration, construction and intended operating conditions.

Can a single lip 30x47x7 seal replace the AO version?
Not automatically. A single lip seal does not provide the same auxiliary contamination protection as the AO double lip configuration.

Frequently Asked Questions by Engineers

Is the 30x47x7 dimension sufficient to select a replacement oil 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 protects the sealing area against external contamination.

What should be inspected before installing a new oil seal?
Check the shaft sealing surface for wear grooves, scratches, corrosion and other mechanical damage. The housing bore should also be clean and suitable for installation.

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 an effective sealing interface.

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