Bearings Flashcards
Plain bearing
Designed for light loads and continuous motion
Frequent maintenance
What do bearing do
Stop contamination
What are support journals of shelf and axis
Journal bearings
Roller bearings
Pivot journeys
Pivot bearing
Axial bearing
What are pivot journals
Accept force in a longitudinal direction
What are supporting journal
Accept forces at right angles to the drilling axis
Sliding bearing
operates in a bearing box, a bearing bushing
or directly in the bearing body.
Bearings for large journal diameters and bearings that cannot be pushed over the shafts during assembly (e.g. crankshafts) must be two-part bearings
What is bearing play
Dependent on the lube and demands of the bearing
What are slowing bearing resistant to
Push forces , operate with little force
What are disvantsge of sliding bearings
High starting resistance
Continues maintenance
What are sliding bearing suitable for
Fast and slow rotational speed
What are the bearing loads
Radial and thrust
What are the 5 types of anti friction bearings
- Tapered
- Needle
- Ball
- Spherical
- Cylindrical
What does an anti friction bearing consist of
the outer and inner raceway, the rolling element and usually a rolling element cage.
Ball bearings
Only take light radial loads Popular Fail under thrust load Very slow starting resistance due to all point contact Has a deep grove
Cylindrical roller bearing
Light Axiel or thrust More radials Thermal expansion Line contact Heavy cage with fewer rollers leads to lower load capacity
Nedle roller bearings
Long radial load
High radial load
Very light axial load
Spherical roller
Self aligning for minor angular displacement
Very height radial load capacity
Robust cage
Tapered roller bearings
Can take combined radial and thrust load Longer life reduced size Low friction coefficient High speeds Less sensitive to contamination
Materials of ball bearings
Copper tin alloys
Copper tin zinc casting alloys
Lead tin alloys
Cast iron
What is a dry powder material
Contain lubrications in pores which escapes when heated
Radial bearings
can accept forces that act radially to the shaft axis. Axial bearings or longitudinal bearings accept forces that act in the direction of the axis of the shaft.
Axial bearings
Accepts forces acting in the shaft direction
Air bearings
Thin film of pressurised air
Zero friction load bearing
Avoid traditional bearing problems
Air cycle machine
