Radial shaft seals, also known as lip seals, are used to seal rotary elements, such as a shaft or rotating bore. Common examples include strut seals,

hydraulic pump Hydraulic pumps are used in hydraulic drive systems and can be hydrostatic or hydrodynamic. A hydraulic pump is a mechanical source of power that converts mechanical power into hydraulic energy ( hydrostatic energy i.e. flow, pressure). It generat ...

seals, axle seals,

power steering A power steering is a mechanical device equipped on a motor vehicle that helps drivers steer the vehicle by reducing steering effort needed to turn the steering wheel, making it easier for the vehicle to turn or maneuver at lower speeds. Hydraul ...

seals, and

valve stem A valve stem is a self-contained valve which opens to admit gas to a chamber (such as air to inflate a tire), and is then automatically closed and kept sealed by the pressure in the chamber, or a spring, or both, to prevent the gas from escaping ...

seals. Early radial shaft seals utilized rawhide as the sealing element, and many present-day

elastomer An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus and high failure strain compared with other materials. The term, a portmanteau of ''elastic p ...

ic seal companies were once

tanneries Tanning may refer to: *Tanning (leather), treating animal skins to produce leather *Sun tanning, using the sun to darken pale skin **Indoor tanning, the use of artificial light in place of the sun **Sunless tanning, application of a stain or dye t ...

. The advent of modern elastomers replaced rawhide, industry also added a

garter spring A garter spring is a coiled steel spring that is connected at each end to create a circular shape, and is used in oil seals, shaft seals, belt-driven motors, and electrical connectors. Compression garter springs exert outward radial forces, whi ...

, which helps the sealing lip compensate for lip wear and elastomer material changes. The seal construction consists of a sprung main sealing lip which has a line contact with the shaft. The line contact is formed by two angles, with the air side angle usually less than the oil side angle. Depending on the seal type these two angles are varied to create a

pressure distribution The pressure coefficient is a dimensionless number which describes the relative pressures throughout a flow field in fluid dynamics. The pressure coefficient is used in aerodynamics and hydrodynamics. Every point in a fluid flow field has its ...

at the seal contact line which has a steeper slope on the oil side of the seal. The shallower the slope on the oil side of the seal, the wetter the seal will run. The spring is positioned such that axially the centerline of the spring is biased to the air side of the lip contact line. These seals can be designed with a wide range of lip configurations to optimize lubrication retention and contaminant exclusion. In order to exclude contaminants numerous types of dust lips or exclusionary lips may be used. Common elastomers include

FKM FKM is a family of fluorocarbon-based fluoroelastomer materials defined by ASTM International standard D1418, and ISO 1629, ISO standard 1629. It is commonly called fluorine rubber or fluoro-rubber. FKM is an abreveation of Fluorine Kautschuk Mate ...

, ACM, NBR,

HNBR Nitrile rubber, also known as nitrile butadiene rubber, NBR, Buna-N, and acrylonitrile butadiene rubber, is a synthetic rubber derived from acrylonitrile (ACN) and butadiene. Trade names include Perbunan, Nipol, Krynac and Europrene. This rubber is ...

, and AEM. In order to resist wear, the compounds'

durometer The Shore durometer is a device for measuring the hardness of a material, typically of polymers. Higher numbers on the scale indicate a greater resistance to indentation and thus harder materials. Lower numbers indicate less resistance and soft ...

(hardness) is typically 70 to 85

Shore A The Shore durometer is a device for measuring the hardness of a material, typically of polymers. Higher numbers on the scale indicate a greater resistance to indentation and thus harder materials. Lower numbers indicate less resistance and soft ...

(between that of an automobile tire and a soft inline-skate wheel). A different seal design for similar applications is a rotating face seal.

Simmerring

A commonly used expression is "Simmerring". This product name and ''Simmer-Ring'' are trademarks of Freudenberg Sealing Technologies. ''Simmerring'' is derived from the name of the developer, the Austrian engineer

Walther Simmer Walther is a masculine given name and a surname. It is a German form of Walter, which is derived from the Old High German ''Walthari'', containing the elements ''wald'' -"power", "brightness" or "forest" and ''hari'' -"warrior". The name was firs ...

, who worked for Freudenberg . The first development 1929 in

Kufstein Kufstein (; Central Bavarian: ''Kufstoa'') is a town in the Austrian state of Tyrol, the administrative seat of Kufstein District. With a population of about 19,600 it is the second largest Tyrolean town after the state capital Innsbruck. The great ...

Tirol Austria, consisted of leather and metal.

Standards

Standards and other documents relating to radial shaft seals *ISO 6194-1:1982 Rotary shaft lip type seals – Nominal dimensions and tolerances *ISO 6194-2:1991 Rotary shaft lip type seals – Vocabulary *ISO 6194-3:1988 Rotary shaft lip type seals – Storage, handling and installation *ISO 6194-4:1988 Rotary shaft lip type seals – Performance test procedures *ISO 6194-5:1990 Rotary shaft lip type seals – Identification of visual imperfections *SAE J946-1989 Application Guide to Radial Lip Seals *RMA OS-4, 1984 Application Guide for Radial Lip Type Shaft Seals *RMA OS-7, 1982 Storage and Handling Guide for Radial Lip Type Shaft Seals *RMA OS-8, 1977 Visual Variations Guide for Rotating Shaft Seals *DIN 3760 Radial-Wellendichtringe (Radial shaft seals) *DIN 3761 Radial-Wellendichtringe für Kraftfahrzeuge (Motor Vehicles Radial shaft seals), Parts 1-15. This standard covers all aspects including vocabulary, material requirements and test methods. *GOST 8752-79. CIS standard for rotary shaft seals.

References

External links

Description & schematic of a shaft seal
{{Authority control Seal rings

Simmerring

Standards

See also

References

External links