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Questions and Answers
What property of bearing material allows it to accommodate repeated loads without developing surface fatigue cracks?
What property of bearing material allows it to accommodate repeated loads without developing surface fatigue cracks?
Which type of clutch connects shafts and enables speed synchronization between driven and driving bodies?
Which type of clutch connects shafts and enables speed synchronization between driven and driving bodies?
What characteristic of a bearing material is important for ensuring it does not corrode when in contact with lubricating oil?
What characteristic of a bearing material is important for ensuring it does not corrode when in contact with lubricating oil?
What is the term used to describe the ability of bearing material to embed small particles without causing damage?
What is the term used to describe the ability of bearing material to embed small particles without causing damage?
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Which type of brake includes examples such as pumps and fluid agitators?
Which type of brake includes examples such as pumps and fluid agitators?
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What does high thermal conductivity in bearing material enable?
What does high thermal conductivity in bearing material enable?
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What is the primary function of a brake as a friction device?
What is the primary function of a brake as a friction device?
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Which type of brakes would include mechanisms such as eddy current brakes?
Which type of brakes would include mechanisms such as eddy current brakes?
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What does the term backlash refer to in gear systems?
What does the term backlash refer to in gear systems?
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What is the pitch circle in gear mechanics?
What is the pitch circle in gear mechanics?
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How is the pressure angle characterized in gear design?
How is the pressure angle characterized in gear design?
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What does the term 'addendum' in gear terminology refer to?
What does the term 'addendum' in gear terminology refer to?
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What is the definition of circular pitch in the context of gears?
What is the definition of circular pitch in the context of gears?
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Which of the following describes the dedendum circle?
Which of the following describes the dedendum circle?
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What aspect does face width in gear design refer to?
What aspect does face width in gear design refer to?
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What does the term 'fillet radius' refer to in gear mechanics?
What does the term 'fillet radius' refer to in gear mechanics?
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What does the term 'clearance' refer to in gear terminology?
What does the term 'clearance' refer to in gear terminology?
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Which statement correctly describes the total depth of a gear?
Which statement correctly describes the total depth of a gear?
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What are the main types of ropes used for transmitting power in rope drives?
What are the main types of ropes used for transmitting power in rope drives?
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What is a key limitation of flat belts in power transmission?
What is a key limitation of flat belts in power transmission?
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What occurs during belt slip?
What occurs during belt slip?
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Which property is crucial for the bearing materials used in contact bearings?
Which property is crucial for the bearing materials used in contact bearings?
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What is normal circular pitch in gears?
What is normal circular pitch in gears?
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What distinguishes rolling contact bearings from sliding contact bearings?
What distinguishes rolling contact bearings from sliding contact bearings?
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Which material is most commonly recommended for medium service for wire rope sheaves?
Which material is most commonly recommended for medium service for wire rope sheaves?
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What is the primary characteristic of bearing materials required for operating over a wide range of temperatures?
What is the primary characteristic of bearing materials required for operating over a wide range of temperatures?
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In the context of viscosity, what does the term 'viscosity index' refer to?
In the context of viscosity, what does the term 'viscosity index' refer to?
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What term describes the lowest temperature at which oil can sustain a flash when ignited?
What term describes the lowest temperature at which oil can sustain a flash when ignited?
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What is kinking in relation to ropes and chains?
What is kinking in relation to ropes and chains?
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Which of the following materials is NOT commonly used for sliding contact bearings?
Which of the following materials is NOT commonly used for sliding contact bearings?
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In a chain drive system, how does the speed of the driven shaft change as the load increases?
In a chain drive system, how does the speed of the driven shaft change as the load increases?
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Which of the following is a property associated with the 'oiliness' of a lubricant?
Which of the following is a property associated with the 'oiliness' of a lubricant?
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Study Notes
Gear Terminology
- Pitch circle: An imaginary circle used to define the rolling action of gears.
- Tooth thickness: The width of a gear tooth measured along the pitch circle.
- Tooth space: The width of the space between two adjacent teeth measured along the pitch circle.
- Pitch circle diameter (PCD): The diameter of the pitch circle. It is often used to specify the size of a gear.
- Pitch point: The point of contact between two pitch circles.
- Pressure angle (ϕ): The angle between the common normal to two gear teeth at the point of contact and the common tangent at the pitch point.
- Addendum: The radial distance from the pitch circle to the top of a tooth.
- Dedendum: The radial distance from the pitch circle to the bottom of a tooth.
- Addendum circle: A circle drawn through the top of the teeth and concentric with the pitch circle.
- Dedendum circle (Root circle): A circle drawn through the bottom of the teeth.
- Circular pitch: The distance measured on the circumference of the pitch circle from a point on one tooth to the corresponding point on the next tooth.
- Diametral pitch: The ratio of the number of teeth to the pitch circle diameter.
- Module: The ratio of the pitch circle diameter to the number of teeth.
- Clearance: The radial distance between the dedendum and addendum.
- Whole depth/Total depth: The radial distance between the addendum and dedendum circles of a gear.
- Working depth: The radial distance from the addendum circle to the clearance circle.
- Backlash: The difference between the tooth space and tooth thickness measured on the pitch circle.
- Face of the tooth: The surface of the tooth above the pitch surface.
- Top land: The surface of the top of the tooth.
- Flank of the tooth: The surface of the tooth below the pitch surface.
- Face width: The width of the gear tooth measured parallel to its axis.
- Profile: The curve formed by the face and flank of the tooth.
- Filet radius: The radius that connects the root circle to the profile of the tooth.
- Path of contact: The path traced by the point of contact of two teeth from the beginning to the end of engagement.
- Helix angle (α): The angle made by the helices with the axis of rotation.
- Transverse circular pitch (Pc): The circular pitch in the plane of rotation or the diametral plane.
- Normal circular pitch: The distance between similar faces of adjacent teeth along a helix on the pitch cylinder normal to the teeth.
Belt Drives
- Belts are used to transmit power between shafts using pulleys.
- They can maintain the same or different speeds.
- Belt slip: When frictional grip between belts and pulleys becomes insufficient, resulting in the driver moving without carrying the belt.
- Flat belts: Used for moderate power transmission between pulleys up to 8 meters apart.
- Rope drives: Effective for large power transmission over distances, using fiber or wire ropes.
Bearings
- Sliding contact bearings (Plain bearings): Motion occurs along the surfaces of contact between the moving and fixed elements.
- Rolling contact bearings: Steel balls or rollers are interposed between the moving and fixed elements.
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Bearing material properties:
- Compressive strength: To withstand maximum pressure and prevent deformation.
- Fatigue strength: To resist repeated loads without developing surface fatigue cracks.
- Comformability: To accommodate shaft deflections and inaccuracies through plastic deformation.
- Embeddability: To accommodate small particles without scoring the material.
- Bondability: Many high-capacity bearings are built by bonding layers of material to a steel shell.
- Corrosion resistance: To prevent corrosion due to lubricating oil.
- Thermal conductivity: For rapid heat removal from friction.
- Thermal expansion: Low coefficient for minimal clearance change.
- Oiliness: Measured by the lubricating qualities under boundary conditions.
- Viscosity index: Indicates the variation of viscosity based on temperature.
- Flash point: The temperature at which an oil produces enough vapor to flash momentarily.
- Fire point: The temperature at which an oil produces enough vapor to burn continuously.
Common Bearing Materials for Sliding Contact
- Babbit metal (Tin-based and Lead-based)
- Bronze
- Brass
- Cast iron
- Silver
- Non-metallic bearings (plastics and rubber)
Rope and Chain
- Kinking: Twisting or curling in ropes and chains due to doubling or bending.
- Conveyor chains: Used for elevating and conveying materials continuously at speeds up to 2 m/s.
- The speed of the driven shaft in a chain drive system decreases as the pitch of the chain increases.
Braking and Clutch Systems
- A brake is a friction device used to regulate the motion of bodies.
- Clutch is a friction device used to connect shafts.
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Types of brakes:
- Hydraulic brakes: Use pumps or hydrodynamic brakes and fluid agitators.
- Electric brakes: Generators and eddy current brakes.
- Mechanical brakes: Radial and axial brakes.
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Types of clutches:
- Positive clutches
- Friction clutches
- Band brake: A braking system where a band wraps partly around the brake drum and tightens for braking action.
- Cast iron is the most commonly recommended material for wire rope sheaves in medium service.
- Annealing: A process that involves heating and slow cooling a metal to alter physical and mechanical properties, producing a specific microstructure, removing internal stresses, and removing gases.
Kinematic Chains
- Link: A rigid member or body in a kinematic chain that joins with other links.
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Description
Test your knowledge on essential gear terminology. This quiz covers critical concepts such as pitch circles, tooth thickness, and pressure angles. Perfect for engineering students and gear enthusiasts looking to enhance their understanding of gear mechanics.
