Podcast
Questions and Answers
Which of the following is the MOST likely cause of a belt exhibiting cracks on its bottom surface?
Which of the following is the MOST likely cause of a belt exhibiting cracks on its bottom surface?
- Foreign material accumulation between the belts of the tie band.
- Obstruction on the sheave interfering with normal belt operation.
- Belt slippage causing heat build-up and hardening of reinforcing fibers. (correct)
- Excessive belt tension leading to fiber fatigue.
A maintenance engineer observes that the top tie band of a belt drive system is consistently fraying. What is the MOST probable cause?
A maintenance engineer observes that the top tie band of a belt drive system is consistently fraying. What is the MOST probable cause?
- The system lacks sufficient lubrication, causing friction.
- The belt is operating under excessively high tension.
- The belt material is inherently defective.
- There is an obstruction on the sheave interfering with the belt's normal path. (correct)
What is the MOST direct consequence of operating a belt drive system with a belt consistently riding outside the sheave groove?
What is the MOST direct consequence of operating a belt drive system with a belt consistently riding outside the sheave groove?
- Immediate catastrophic failure of the belt.
- Increased energy efficiency due to reduced friction.
- Progressive failure of the belt, potentially leading to separation. (correct)
- Improved grip between the belt and sheave, extending belt life.
Which combination of factors is MOST likely to cause separation in a belt drive system?
Which combination of factors is MOST likely to cause separation in a belt drive system?
In gear systems, what is the underlying mechanism that leads to overload wear, resulting in micro-welds and particle detachment?
In gear systems, what is the underlying mechanism that leads to overload wear, resulting in micro-welds and particle detachment?
What is the fundamental difference between pitting and spalling in gear teeth, and what primary condition is associated with both?
What is the fundamental difference between pitting and spalling in gear teeth, and what primary condition is associated with both?
Distinguish between the causes of gear cracking and breakage, and how to differentiate between impact overloading and fatigue failure in broken gears.
Distinguish between the causes of gear cracking and breakage, and how to differentiate between impact overloading and fatigue failure in broken gears.
How does misalignment contribute to interference wear in gear systems, and where is this type of wear MOST likely to manifest?
How does misalignment contribute to interference wear in gear systems, and where is this type of wear MOST likely to manifest?
What conditions exacerbate abrasive wear in gears, and what potential secondary damage can result from this type of wear?
What conditions exacerbate abrasive wear in gears, and what potential secondary damage can result from this type of wear?
What are the FIRST signs of gear corrosion in a lubricated system, and what underlying conditions typically contribute to it?
What are the FIRST signs of gear corrosion in a lubricated system, and what underlying conditions typically contribute to it?
How does a complete breakdown of lubrication lead to gear burning, and what mechanical property of the gear material is MOST affected?
How does a complete breakdown of lubrication lead to gear burning, and what mechanical property of the gear material is MOST affected?
What are the primary purposes of backlash in gear systems, and how does excessive backlash typically manifest?
What are the primary purposes of backlash in gear systems, and how does excessive backlash typically manifest?
Describe a scenario where despite proper initial gear manufacturing and alignment, a gear system begins to exhibit signs of overload wear. What proactive measures could be implemented to mitigate this issue?
Describe a scenario where despite proper initial gear manufacturing and alignment, a gear system begins to exhibit signs of overload wear. What proactive measures could be implemented to mitigate this issue?
In a gear system operating in a humid environment, what specific steps should be taken during maintenance to prevent corrosion, and why are these steps crucial?
In a gear system operating in a humid environment, what specific steps should be taken during maintenance to prevent corrosion, and why are these steps crucial?
If a gear system is experiencing frequent lubrication breakdowns leading to burning, what measures should be taken to prevent recurrence, focusing on both lubricant selection and system design?
If a gear system is experiencing frequent lubrication breakdowns leading to burning, what measures should be taken to prevent recurrence, focusing on both lubricant selection and system design?
Flashcards
Bottom of Belts Cracking
Bottom of Belts Cracking
Cracks on the bottom of a belt, caused by belt slipping leading to heat build-up and hardening of reinforcing fibres.
Top of Tie Band Frayed/Damaged
Top of Tie Band Frayed/Damaged
Fraying or damage on the top of tie band, caused by obstruction on the sheave interfering with normal belt operation.
Top of Tie Band Blistered/Perforated
Top of Tie Band Blistered/Perforated
Blisters or perforations on the top of the tie band, caused by foreign material accumulating between the belts of tie band.
Overload Wear
Overload Wear
Overload wear occurs when metal has been removed from the tooth surface by the sliding action of a gear’s teeth. The heavy contact tends to squeeze out the lubricant, the metal forms micro-welds and tiny particles can be torn free.
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Pitting and Spalling
Pitting and Spalling
Pitting is small surface cavities. Spalling is when pieces flake off altogether. Caused by thin oil and high temps, may indicate faulty hardening.
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Cracking and Breakage
Cracking and Breakage
Cracking is usually caused by faulty heat treatment or improper machining during manufacture. Breakage can be caused by one of many faults, from impact loading to manufacturing faults.
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Interference Wear
Interference Wear
Heavy contact is caused in small areas, often at teeth tips and roots.
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Abrasive Wear
Abrasive Wear
Scratching and scoring from abrasive particles in the lubricant. Scoring is heavy gouging as lubricant thins.
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Gear Corrosion
Gear Corrosion
Often moisture is present in the lubricant along with contaminants, which react to become acidic and corrosive.
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Gear Burn
Gear Burn
Friction causes rapid heating past the temperature limits of the metal, resulting in brittle teeth which are easily broken.
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Normal Wear
Normal Wear
A polished appearance over the entire surface of the tooth.
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Backlash
Backlash
The clearance or play between two gears in mesh.
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Excessive Backlash Causes
Excessive Backlash Causes
Worn gear teeth or improper meshing of teeth or bearings.
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- Belt drives can be single or multiple belt and pulley systems.
Belt Defects
- Bottom cracking is caused by slipping, leading to heat build-up, friction, and hardening of under-cord reinforcing fibres.
- A frayed or damaged top tie band comes from obstruction on the sheave interfering with belt operation.
- A blistered or perforated top tie band results from foreign material accumulating between tie band belts.
- Cuts on the bottom are caused by belts running over sheaves, coming off, or being forced over sheave flanges during installation without proper slack.
- Belts riding outside sheave grooves lead to progressive failure like separation if allowed to continue.
- Separation is caused by improper belt tension, sheave misalignment, or foreign objects striking the belt.
Gear Wear Types
- Overload wear occurs when metal is removed from the tooth surface by the sliding action of gear teeth, leading to micro-welds and particle loss.
- Overload wear can leave depressions, burrs on the tooth edge, or plastic deformations.
- Pitting and spalling are linked to thin oil films and high temperatures, resulting in pitting on teeth or fine cracking.
- Spalling is due to faulty hardening, which means metal flakes away and chips damage other teeth.
- Cracking results from faulty heat treatment or improper machining during gear manufacture.
- Breakage is caused by impact loading or manufacturing faults, fresh metal indicates impact overloading, while darker edges point to fatigue from a surface crack.
- Interference wear is caused by misalignment of gears or improper meshing of teeth, leading to heavy contact in small areas, often at teeth tips and roots.
- Abrasive wear includes scratching and scoring, depending on the size of particles in the lubricant which abrade the tooth surface.
- Scoring involves heavy gouging of metal from the tooth surface as temperature rises and lubricant thins, with metal pieces potentially damaging other teeth.
- Excessive backlash and poor lubrication are the main causes of gear failure or premature wear.
- Proper alignment and fit are important for each tooth to absorb its share of the load.
- Gears corrode when exposed to corrosive environments, often caused by moisture and contaminants in the lubricant turning acidic.
- A complete breakdown or lack of lubrication causes the gear to burn, and friction leads to rapid heating beyond temperature limits, making teeth brittle.
- Normal wear shows as a polished appearance over the entire tooth surface.
- Backlash is the clearance between two gears in mesh, needed for lubricant penetration and thermal expansion.
- Excessive backlash results from worn gear teeth or improper meshing due to inadequate bearing support.
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