A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts.
Rotary bearings hold rotating components such as shafts or axles within mechanical systems, and transfer axial and radial loads from the source of the load to the structure supporting it. The simplest form of bearing, the plain bearing, consists of a shaft rotating in a hole. Lubrication is used to reduce friction. In the ball bearing and roller bearing, to reduce sliding friction, rolling elements such as rollers or balls with a circular cross-section are located between the races or journals of the bearing assembly. A wide variety of bearing designs exists to allow the demands of the application to be correctly met for maximum efficiency, reliability, durability and performance.
Keywords
hole
type
axles
axial
parts
balls
races
shafts
source
vectors
example
rollers
motions
demands
journals
structure
operation
fixed axis
durability
directions
Lubrication
application
moving part
reliability
performance
radial loads
ball bearing
wide variety
plain bearing
Most bearings
simplest form
free rotation
normal forces
desired motion
roller bearing
relative motion
bearing designs
Rotary bearings
machine element
bearing assembly
rolling elements
sliding friction
maximum efficiency
mechanical systems
rotating components
free linear movement
circular cross-section
