Bearing isolators – Renault Engineers
Bearing isolators are dynamic seals designed to protect bearings from outside contaminants. They are comprised of a rotor (rotating) and stator (stationary) member.
Some bearing isolators are of labyrinth construction while others use O-rings or other positive seals.
Specifications
The most important specifications to consider when searching for bearing isolators are the dimensions. These include:
- shaft outer diameter or seal inner diameter
- housing bore diameter or seal outer diameter
- axial cross section or thickness
The shaft outer diameter or seal inner diameter refers to the size of the seal inside diameter or the shaft or piston outside diameter. The housing bore diameter or seal out diameter refers to the size of the housing bore diameter or the seal outside diameter. The axial cross section or thickness refers to the axial cross section, or thickness, of the seal.
Features
When considering bearing isolators, important service limit parameters include maximum operating speed, pressure, temperature, and vacuum rating. Maximum operating speed is measured in ft/min or m/sec.
The seal’s maximum pressure indicates its failure threshold. Operating temperature refers to the ambient temperature range.
Some seals operate in a vacuum. Common features of bearing isolators are spring loaded, integral wiper or scraper, and split seals. Spring loaded seals, also known as spring-energized, maintain contact with the shaft. Wiper or scraper elements prevent contamination.
Elastomeric seals have a split for easier assembly, while rigid seals resemble piston rings in functionality.
Bearing isolators – Renault Engineers
Materials
Common materials of construction for the sealing element or lip material include:
- clearance or labyrinth construction
- ethylene acrylic
- fluoroelastomer
- fluorosilicone
- nitrile
- highly saturated nitrile
- nylon or polyamide
- polyacrylate
- polychloroprene
- polyetheretherkeytone
- polyoxymethylene
- polyurethane or urethane
- natural rubber
- sintered bronze
- cast iron
- stainless steel
- felt
- leather
A polymer is a solid, nonmetallic compound of high molecular weight and with a structure composed of small repeat units (mers). Plastics and elastomers are polymers. Many seal manufacturers use their own proprietary material. Where possible, these materials have been categorized into the generic equivalent of material family. Consult with the manufacturer for proprietary material specifications
Bearing isolators – Renault Engineer
