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What is the primary purpose of disassembling a component in bearing maintenance?
Which of the following is NOT a visual indication of a bearing problem?
What is the primary reason for rejecting split-shell plain bearings automatically?
Which of the following bearing defects is characterized by a scratch or mark on the raceway?
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What is the relationship between inspection and testing in bearing maintenance?
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What is the purpose of cleaning a bearing before inspection?
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What happens to the balls or rollers in a bearing when it operates with proper lubrication and at the right speed?
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What is the result of the combination of metal-to-metal contact and vibration in a bearing?
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What is the primary cause of spalling in a bearing?
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What is the appearance of spalling in a bearing?
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What is the term 'brinelling' reminiscent of?
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What happens to the metal of the bearing ringway under cyclic loading?
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What is the result of the flaking of small metal particles from the bearing ringway?
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What is the primary difference between true and false brinelling?
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Which type of brinelling is caused by excessive shock loadings applied to the bearing while it is stationary?
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What is the common factor between mounting brinelling and radial brinelling?
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What is the primary cause of false brinelling?
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What is the appearance of radial brinelling in the races?
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What is the primary cause of galling in bearings?
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What is the result of metal-to-metal contact in galling?
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What is the effect of fine dust particles in bearings?
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What is the outcome of flaking in bearings?
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What is the primary cause of bearing wear?
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What is the result of skidding in galling?
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What is the recommended speed for passing the bearing through the coil of a demagnetiser?
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Why is the bearing rotated by 90° as it passes through the demagnetiser coil?
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What is the acceptable level of residual magnetism for large bearings?
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What is the unit of measurement used by a gaussmeter?
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What happens to the voltage at each edge of the semiconductor slab when a magnetic field is applied?
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What is the name of the device that measures the strength and direction of magnetic fields?
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Study Notes
Brinelling
- Brinelling involves indentations in bearing raceways at intervals, resembling marks from a Brinell hardness test.
- Distinguished into two types: true brinelling and false brinelling.
- True brinelling results from excessive load surpassing the elastic limit of the bearing material.
- False brinelling occurs due to vibration, not necessarily from high load.
- Common causes include:
- Incorrect fitting (mounting brinelling)
- Stationary loading (radial brinelling)
- Vibration during transportation (shipping brinelling)
Bearing Defects – Brinelling Examples
- Mounting Brinelling: Indentations occur from improper fitting or removal, often pushing rolling elements into the raceway shoulder.
- Radial Brinelling: Features elliptical impressions caused by shock loads when the bearing is stationary, centered in raceways.
Spalling
- Spalling is the breakdown of surfaces from cyclic loading, leading to localized metal fatigue.
- Appears as irregular pitting with cracked edges and can result in large metal area losses from balls or raceways.
- Continuous flexing under high pressure from rolling elements contributes to spalling.
De-magnetising Procedure
- Involves passing a bearing through a demagnetiser's coil, rotating it by 90° during the process.
- Should not exceed 12 ft per second speed during demagnetising.
- A gaussmeter tests residual magnetism post-process, with acceptable levels being 5 Gs for large bearings and 2 Gs for smaller ones.
Gaussmeter
- Measures the effectiveness of de-magnetising, calibrated in gauss (Gs).
- Functions as a magnetometer to evaluate magnetic field strength and direction.
- Utilizes a Hall element to detect voltage changes, proportional to magnetic flux density.
Bearing Maintenance
- Maintenance includes disassembling, inspecting, cleaning, testing, and lubricating bearings.
- Inspections must align with maintenance manuals, detecting surface flaws, overheating, and lubricant issues.
- Visual examinations identify faults like:
- Broken or cracked races
- Dented seals
- Cracked separators
- Damaged balls or rollers
- Overheating discoloration
- Less visible defects include brinelling, burnishing, galling, and spalling.
Galling
- Occurs from skidding of rolling elements leading to metal transfer due to welding/tearing at contact points.
- Causes include over-speeding, overloading, poor lubrication, and insufficient clearance.
Flaking
- Results from small pieces of bearing material separating from smooth surfaces due to rolling fatigue.
- Creates coarse texture regions that can lead to failure.
Wear
- Contamination from dirt and hard particles can cause roughness in the bearing ringway and balls.
- Fine dust acts like a lapping compound, accelerating wear and potential failure.
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Description
This quiz covers the essential practices and procedures for maintaining and inspecting aircraft bearings, including disassembly, cleaning, testing, and lubrication. It also highlights the importance of visual examinations in detecting common problems with bearings. Test your knowledge of aircraft bearing maintenance and inspection!
