1. Gears
Classification of gears – Gear tooth terminology - Fundamental Law of toothed gearing and involute gearing – Length of path of contact and contact ratio - Interference and undercutting - Gear trains – Simple, compound and Epicyclic gear trains - Differentials
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2. Spur Gears
Gears: Gears are machine elements that transmit motion by means of successively engaging teeth. The gear teeth act like small levers.
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3. Power transmission systems
Belt/Rope Drives Large center distance of the shafts
Chain Drives Medium center distance of the shafts
Gear Drives Small center distance of the shafts
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4. Friction Discs
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5. Spur Gears animation
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6. Bevel Gears animation
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7. Applications animation
Conveyor/Counting
Gear train
Watch gear wheels
Gear Pump
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8. Industrial Applications
Industrial Applications
Diesel engine builders
Printing machinery parts
Rotary die cutting machines
Hoists and Cranes
Blow molding machinery
Boat out drives
Agricultural equipment
Automotive prototype and reproduction
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9. Industrial Applications
Industrial Applications
Newspaper Industry Plastics machinery
Motorcycle Transmissions Polymer pumps
Automotive applications
Commercial and Military operations
Special gear box builders
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10. Industrial Applications
Industrial Applications
Heavy earth moving vehicles
Canning and bottling machinery builders
Special machine tool builders
Book binding machines Marine applications
Injection molding machinery
Military off-road vehicles Stamping presses
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11. 1. Gears for connecting parallel shafts
Classification
Gears may be classified according to the relative position of the axes of revolution. The axes may be parallel, intersecting and neither parallel nor intersecting.
1. Gears for connecting parallel shafts
Spur Gears: External contact Internal contact
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12. (Double Helical gears)
Parallel Helical gears Heringbone gears
(Double Helical gears)
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13. 2. Gears for connecting intersecting shafts – Bevel Gears
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14. Bevel gears Straight bevel gears Spiral bevel gears 4/17/2017
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15. 3. Gears for neither parallel nor intersecting shafts.
Crossed-helical gears
Worm & Worm Wheel
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16. Rack and Pinion
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17. Worm and Worm Wheel
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18. Hypoid Gear
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19. Hypoid Gear
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20. Gear Box
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21. Terminology Spur Gears
Vvvvv
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22. Terminology
                         
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23. Definitions
Addendum: The radial distance between the Pitch Circle and the top of the teeth.
Arc of Action: Is the arc of the Pitch Circle between the beginning and the end of the engagement of a given pair of teeth.
Arc of Approach: Is the arc of the Pitch Circle between the first point of contact of the gear teeth and the Pitch Point.
Arc of Recession: That arc of the Pitch Circle between the Pitch Point and the last point of contact of the gear teeth.
Backlash: Play between mating teeth.
                         
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24. Definitions
Base Circle: The circle from which is generated the involute curve upon which the tooth profile is based.
Center Distance: The distance between centers of two gears.
Chordal Addendum: The distance between a chord, passing through the points where the Pitch Circle crosses the tooth profile, and the tooth top.
Chordal Thickness: The thickness of the tooth measured along a chord passing through the points where the Pitch Circle crosses the tooth profile.
Circular Pitch: Millimeter of Pitch Circle circumference per tooth.
                         
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25. Definitions
Circular Thickness: The thickness of the tooth measured along an arc following the Pitch Circle
Clearance: The distance between the top of a tooth and the bottom of the space into which it fits on the meshing gear.
Contact Ratio: The ratio of the length of the Arc of Action to the Circular Pitch.
Dedendum: The radial distance between the bottom of the tooth to pitch circle.
Diametral Pitch: Teeth per mm of diameter.
                         
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26. Definitions
Face: The working surface of a gear tooth, located between the pitch diameter and the top of the tooth.
Face Width: The width of the tooth measured parallel to the gear axis.
Flank: The working surface of a gear tooth, located between the pitch diameter and the bottom of the teeth
Gear: The larger of two meshed gears. If both gears are the same size, they are both called "gears".
Land: The top surface of the tooth.
                         
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27. Definitions
Line of Action: That line along which the point of contact between gear teeth travels, between the first point of contact and the last.
Module: Millimeter of Pitch Diameter to Teeth.
Pinion: The smaller of two meshed gears.
Pitch Circle: The circle, the radius of which is equal to the distance from the center of the gear to the pitch point.
Diametral pitch: Teeth per millimeter of pitch diameter.
Pitch Point: The point of tangency of the pitch circles of two meshing gears, where the Line of Centers crosses the pitch circles.
                         
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28. Definitions
Pressure Angle: Angle between the Line of Action and a line perpendicular to the Line of Centers.
Profile Shift: An increase in the Outer Diameter and Root Diameter of a gear, introduced to lower the practical tooth number or acheive a non-standard Center Distance.
Ratio: Ratio of the numbers of teeth on mating gears.
Root Circle: The circle that passes through the bottom of the tooth spaces.
Root Diameter: The diameter of the Root Circle.
Working Depth: The depth to which a tooth extends into the space between teeth on the mating gear.
                         
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29. Formulae
                         
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30. Formulae
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31. Forumulae Specific to Gears with Standard Teeth
Addendum = 1 ÷ Diametral Pitch = × Circular Pitch
Dedendum = ÷ Diametral Pitch = × Circular Pitch
Working Depth = 2 ÷ Diametral Pitch = × Circular Pitch
Whole Depth = ÷ Diametral Pitch = × Circular Pitch
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32. Forumulae Specific to Gears with Standard Teeth
Clearance = ÷ Diametral Pitch = 0.05 × Circular Pitch
Outside Diameter = (Teeth + 2) ÷ Diametral Pitch = (Teeth + 2) × Circular Pitch ÷ π
Diametral Pitch = (Teeth + 2) ÷ Outside Diameter
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33. Law of Gearing
Tooth profile 1 drives tooth profile 2 by acting at the instantaneous contact point K.
N1 N2 is the common normal of the two profiles. 
N1 is the foot of the perpendicular from O1 to N1N2
N2 is the foot of the perpendicular from O2 to N1N2.
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34. Law of Gearing
Although the two profiles have different velocities V1 and V2 at point K, their velocities along N1N2 are equal in both magnitude and direction. Otherwise the two tooth profiles would separate from each other. Therefore, we have 
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35. Law of Gearing
We notice that the intersection of the tangency N1N2 and the line of center O1O2 is point P, and from the similar triangles 
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36. Law of Gearing Therefore, velocity ratio  4/17/2017
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37. Law of Gearing From the equations 4.2 and 4.4, we can write,
-ratio of the radii of the two base circles and also given by;
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38. Law of Gearing
-centre distance between the base circles 
 = pressure angle or the angle of obliquity. It is angle between the common normal to the base circles and the common tangent to the pitch circles.
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39. Constant Velocity Ratio
A common normal (the line of action) to the tooth profiles at their point of contact must, in all positions of the contacting teeth, pass through a fixed point on the line-of-centers called the pitch point
Any two curves or profiles engaging each other and satisfying the law of gearing are conjugate curves, and the relative rotation speed of the gears will be constant (constant velocity ratio). 
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40. Conjugate Profiles
To obtain the expected velocity ratio of two tooth profiles, the normal line of their profiles must pass through the corresponding pitch point, which is decided by the velocity ratio. The two profiles which satisfy this requirement are called conjugate profiles. 
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41. Conjugate action
It is essential for correctly meshing gears, the size of the teeth ( the module ) must be the same for both the gears.
Another requirement - the shape of teeth necessary for the speed ratio to remain constant during an increment of rotation; this behaviour of the contacting surfaces (ie. the teeth flanks) is known as conjugate action.
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43. THANK YOU BY SKA
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