Bearing Seal, Shield, and Clearance Suffixes

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Bearing suffixes add critical detail to a base bearing designation. They commonly identify whether a bearing is open, fitted with rubber seals or metal shields, or supplied with a particular internal-clearance group.

For example, 6204-2RS-C3 combines a base designation with two rubber seals and greater-than-normal internal clearance. The suffixes help describe the bearing, but their exact construction and complete meaning must be checked against the relevant manufacturer catalog.

Bearing seal and shield suffixes

Seal and shield markings commonly describe closure arrangements at one or both sides of a bearing. A suffix can indicate rubber seals, metal shields, or a manufacturer’s wording for a non-contact rubber seal.

Suffix Common reading Limit
2RS, 2RS1, 2RSH Two rubber seals Seal lip and material details vary by manufacturer
RS, RS1, RSH One rubber seal The unsealed side and seal design require catalog context
ZZ or 2Z Two metal shields Manufacturers may use either spelling
Z One metal shield The other side may be open or described elsewhere
2RU or RU Non-contact rubber seal wording Confirm drag and construction in the exact catalog

ZZ and 2Z are commonly read as two metal shields, even though manufacturers may prefer one notation over the other. Similarly, 2RS, 2RS1, and 2RSH are commonly interpreted as bearings with two rubber seals, but the specific seal design is not established by the short suffix alone.

A one-side suffix such as Z, RS, RS1, or RSH requires extra care. It indicates one shield or seal under the common parser reading, while the configuration of the other side must be confirmed from the full designation and manufacturer documentation.

Bearing clearance suffixes

Clearance suffixes identify an internal-clearance group. Common groups recognized in bearing designations include:

Suffix Common interpretation
C1 Clearance group
C2 Clearance group
CN Normal clearance group
C3 Greater-than-normal internal clearance
C4 Internal-clearance group greater than C3
C5 Internal-clearance group greater than C4

C3 is commonly used to indicate greater-than-normal internal clearance. C4 and C5 indicate progressively larger clearance groups in common designation wording.

The suffix alone does not provide an actual clearance measurement. Actual values are governed by applicable standards and manufacturer data, including ISO rolling-bearing references such as ISO 5753-1 for radial internal clearance.

Reading suffixes with the base number

A suffix describes only part of a bearing designation. It must be read together with the base number rather than copied from one bearing number to another.

For example:

  • 6205-ZZ indicates a bearing with two metal shields under the common suffix reading.
  • 6203-2Z also indicates two metal shields, but it has a different base designation and bore.
  • 6204-2RS-C3 combines a base designation, two rubber seals, and greater-than-normal internal clearance.

Two bearings can therefore share a closure suffix while remaining different bearings. The base number and suffixes work together; the suffix does not establish outside diameter, width, cage material, lubrication, fit, load rating, or interchangeability.

Why some clearance-like suffixes are rejected

A marking such as 6204-C99 may resemble a clearance suffix because it begins with C. However, C99 is not one of the common clearance groups C1, C2, CN, C3, C4, or C5.

Treating unsupported C-prefixed markings as harmless unknown text can be misleading because the C prefix has a specific clearance meaning in many bearing catalogs. A decoder should reject an unsupported clearance-like suffix rather than assign it an unverified interpretation.

Using the Bearing Number Decoder

The Bearing Number Decoder parses common bearing suffixes and keeps unresolved suffixes visible rather than hiding them.

Use the decoded result as a structured first reading of the marking:

  1. Enter the complete bearing designation, including suffixes.
  2. Review the base designation separately from seal, shield, and clearance suffixes.
  3. Treat recognized suffixes as common parser readings.
  4. Check unresolved or rejected suffixes against the exact manufacturer catalog.
  5. Confirm the complete bearing designation before purchasing, comparing, or using it for maintenance work.

The decoder does not establish manufacturer-specific seal construction, exact clearance values, dimensions beyond supported bore-code parsing, lubrication, cage material, load rating, fit, or interchangeability.

Catalog checks and designation limits

Basic bearing designations can be standardized, while supplementary suffixes may be manufacturer-specific. NSK bearing designation guidance, JTEKT/Koyo bearing number tables, SKF designation guidance, ISO rolling-bearing references, and ANSI/ABMA tapered roller bearing references provide relevant context for interpreting designations.

Metric tapered roller bearings and inch-design tapered roller bearings use separate designation systems. Confirm the exact catalog entry before treating a suffix as equivalent across bearing types or manufacturers.

Bearing seal, shield, and clearance suffixes are most useful when read as part of the complete designation. Use 2RS, ZZ, 2Z, Z, C3, C4, and related markings to identify the common closure or clearance description, then verify manufacturer-specific details in the applicable catalog.

Related bearing guides

How to Read Bearing Numbers | 6205-ZZ vs 6203-2Z Bearing Number | Bearing Number Parser Limits