7.11 Flashcards
What are the bearings for supporting journals, destined to accept force at right angle to drilling axis?
Journal or Roller bearings.
What bearings are designed to accept forces in a longitudinal direction?
Pivot and Axial bearings.
What loads do sliding bearings resist?
Radial loads.
What are advantages of sliding bearings?
Operate with little noise and suitable for both slow and fast rotational journal speeds.
What are disadvantages of sliding bearings?
The have a high starting resistance and require continuous maintenance.
What are the 5 basic types of anti-friction bearings?
Tapered Roller Needle Spherical Roller Cylindrical Roller Ball
What is one of the most popular lubricants?
Grease.
Why is it bad to over grease bearings?
Can cause excess churning and generate extremely high temperatures.
What is grease applied with?
A grease packer.
What are symptoms of overheating in bearings?
Discolouration of the rings, balls and cages from gold to blue.
What temperatures can anneal the ring and ball materials in bearings?
400 Fahrenheit.
What is false brinelling?
Wear in a bearing from excessive vibration.
How does true brinelling occur?
When loads exceed elastic limit.
How do you know if true brinelling is present?
Indentations in the raceways which increase bearing noise and vibration.
How is false brinelling evident?
Elliptical wear marks in an axial direction, and a ring of brown debris.
What is fatigue failure on bearings also known as?
Spalling.
Fracture and removal of particles of material
What load are angular contact bearings designed to accept?
Axial load in one direction.
What is one of the leading causes of bearing failure?
Contamination.
What symptoms are contamination of bearings?
Denting of the raceways and balls.
What are symptoms of lubricant failure in bearings?
Discoloured (blue/brown) balls and tracks.
What are signs of corrosion on bearings?
Red/brown areas on balls, cages and bands of ball bearings.
How is misalignment on a bearing detected?
A ball wear path that is not parallel to raceways edges.
What is fretting on a bearing?
Generation of fine metal particles which oxidise and leave a brown colour.
How does fretting on bearings occur?
If the relative motion between mating parts is slight but continuous.
What constant temperature do bearings have to be repaired at?
20 Celsius
When do bearings have to be greased after final rinse?
Within 2 hours.
What must humidity be less than for storage of bearings?
75%
What is VCI for bearings?
Vapour Corrosion Inhibitor.
