Simmerring – Rotary Shaft Seal

Rotating machine components require proper shaft sealing to prevent grease or oil leaks and keep contaminants out. Known as radial shaft seals or Simmerrings, they play a vital role in machinery by extending service life and maintaining performance.

What is a Simmerring?

The name derives from German. It's a rotary seal ring designed for rotating parts exposed to grease, oil, fuel, or water. Operating range: up to 0.1 MPa, –30 °C to +110 °C depending on seal material.

Construction of a Simmerring

Four key components:

• Metal reinforcement case

• Sealing lip made of NBR, FPM, silicone, etc.

• Pressure spring for consistent sealing

• Optional dust lip for protection

Common materials include NBR, FPM/Viton®, silicone, ACM, and PTFE.

Choosing the Right Material

• NBR: –30 °C to +100 °C, oil and grease resistant

• FPM/Viton®: –20 °C to +200 °C, chemical and ozone resistant

• Silicone: –60 °C to +200/230 °C, wide temperature range

• ACM: –20 °C to +150 °C, for hot oil and atmospheric resistance

• PTFE: memory effect material, can replace spring in some designs

Common Simmerring Types

• Type A (single lip + spring)

• Type AO (dual lip + dust seal)

• Types B, BO (single lip without elastomer coating)

• Specialized varieties: Duo, Combi, RWDR (modular cassette), ZBA/ZBL (no spring)