GRN 55x72x12 NBR AO/TC Double Lip Radial Shaft Seal

GRN 55x72x12 NBR AO/TC is a double lip radial shaft seal (oil seal) manufactured from NBR. Its dimensions are 55x72x12 mm, corresponding to a 55 mm shaft diameter, 72 mm housing bore and 12 mm seal width. The AO/TC profile combines a spring-loaded primary sealing lip with an additional protective lip.

GRN 55x72x12 NBR AO/TC - Characteristics

The primary function of this seal is to provide dynamic sealing between a stationary housing and a rotating shaft. The main sealing lip runs against the shaft surface and limits lubricant leakage from the sealed assembly.

The additional lip of the AO/TC double lip design provides a secondary barrier on the external side, helping reduce the entry of dust and other contaminants toward the primary sealing area.

Dimensions

The 55x72x12 mm dimensions are interpreted as:

d - Shaft Diameter: 55 mm
D - Housing Bore Diameter: 72 mm
B - Seal Width: 12 mm
Complete Size: 55x72x12 mm

All three dimensions must correspond to the sealing position. Dimensions alone, however, do not identify the complete seal specification, so the NBR material and AO/TC profile should also be considered when selecting a replacement.

AO/TC Double Lip Construction

The AO/TC profile is a double lip radial shaft seal design. It incorporates a primary dynamic sealing lip and an additional protective lip.

The main sealing lip is supported by a garter spring, which maintains radial contact between the elastomeric lip and the shaft sealing surface. The secondary lip faces the external side and acts as an additional barrier against contamination.

The two lips therefore perform different functions: the primary lip controls the sealed medium, while the additional lip protects the primary sealing zone.

NBR Material

The seal is manufactured from NBR - Nitrile Butadiene Rubber. NBR is widely used for radial shaft seals because of its compatibility with many mineral oils and greases.

Material compatibility should nevertheless be verified against the actual medium and operating conditions. The designation NBR alone does not establish compatibility with every fuel, synthetic lubricant or chemical.

Primary and Protective Lip Functions

In the GRN 55x72x12 NBR AO/TC, the spring-loaded primary lip forms the dynamic sealing interface with the rotating shaft.

The additional protective lip operates on the external side of the primary lip and helps restrict contamination from reaching the main sealing zone.

This construction differentiates the AO/TC version from a corresponding single lip seal and should be considered when replacing an existing seal.

Selection and Interchangeability

A replacement for GRN 55x72x12 NBR AO/TC should not be selected solely by matching the 55x72x12 mm dimensions.

The following characteristics should be verified:

Shaft Diameter: 55 mm
Housing Bore Diameter: 72 mm
Width: 12 mm
Material: NBR
Design: AO/TC double lip
Protective Lip: present
Primary Lip: spring-loaded

A 55x72x12 mm seal manufactured from FKM/FPM, ACM or another elastomer is not automatically equivalent. Similarly, a single lip seal with identical dimensions has a different sealing configuration.

Technical Specification

Brand: GRN
Product Type: Radial shaft seal / oil seal
Profile: AO/TC
Design: Double lip
Material: NBR - Nitrile Butadiene Rubber
Shaft Diameter d: 55 mm
Housing Bore Diameter D: 72 mm
Width B: 12 mm
Dimensions: 55x72x12 mm
Primary Lip: Dynamic sealing lip
Additional Lip: Protective lip
Spring: Garter spring supporting the primary sealing lip

FAQ

What are the dimensions of GRN 55x72x12 NBR AO/TC?

The seal measures 55x72x12 mm: shaft diameter d = 55 mm, housing bore diameter D = 72 mm and width B = 12 mm.

What does AO/TC mean?

AO/TC identifies a double lip radial shaft seal design with a primary sealing lip and an additional protective lip.

What is the purpose of the second lip?

The additional lip helps restrict dust and other external contaminants from reaching the primary dynamic sealing area.

What does NBR mean?

NBR stands for Nitrile Butadiene Rubber, an elastomer widely used in radial shaft seals operating with many mineral oils and greases.

Is GRN 55x72x12 NBR AO/TC a spring-loaded seal?

Yes. The primary dynamic sealing lip is supported by a garter spring that maintains contact with the shaft sealing surface.

Can a single lip 55x72x12 seal replace the AO/TC version?

Not automatically. The AO/TC configuration includes an additional protective lip, so the required seal design and operating environment should be checked before substitution.

Can any 55x72x12 oil seal be used as an equivalent?

No. Matching dimensions do not establish full interchangeability. Material, lip configuration, housing interface and operating conditions must also be compared.

AI Overview

GRN 55x72x12 NBR AO/TC is a double lip radial shaft seal for a 55 mm shaft and 72 mm housing bore, with a width of 12 mm. The NBR seal uses a spring-loaded primary sealing lip and an additional protective lip that helps restrict external contamination from reaching the main sealing zone.