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Pichet Pinit

MTE 427 MACHINE DESIGN. Pichet Pinit. Fundamentals of Gears. 7 Sep, 2008. Template provided by. Gear. Gears are toothed cylindrical wheels used for transmitting mechanical power from one rotating shaft to another. Several types of gears are in common use. Four principal types of gears are:

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Pichet Pinit

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  1. MTE 427 MACHINE DESIGN Pichet Pinit Fundamentals of Gears 7 Sep, 2008 Template provided by

  2. Gear Gears are toothed cylindrical wheels used for transmitting mechanical power from one rotating shaft to another. • Several types of gears are in common use. Four principal types of gears are: • Spur gears • Helical gears • Bevel gears • Worm gears.

  3. Type of Gear Gears are toothed cylindrical wheels used for transmitting mechanical power from one rotating shaft to another. • Several types of gears are in common use. Four principal types of gears are: • Spur gears • Helical gears • Bevel gears • Worm gears.

  4. Type of Gear Gears are toothed cylindrical wheels used for transmitting mechanical power from one rotating shaft to another. • Several types of gears are in common use. Four principal types of gears are: • Spur gears • Helical gears • Bevel gears • Worm gears.

  5. Type of Gear Gears are toothed cylindrical wheels used for transmitting mechanical power from one rotating shaft to another. • Several types of gears are in common use. Four principal types of gears are: • Spur gears • Helical gears • Bevel gears • Worm gears.

  6. Type of Gear Gears are toothed cylindrical wheels used for transmitting mechanical power from one rotating shaft to another. • Several types of gears are in common use. Four principal types of gears are: • Spur gears • Helical gears • Bevel gears • Worm gears.

  7. Gear Materials and Useful Ratios

  8. Common Gear Types and Pinion Shafts

  9. Load Distribution on Gear Faces

  10. Nomenclature of Spur Gear

  11. Nomenclature of Spur Gear Pitch circle. This is a theoretical circle on which calculations are based. Its diameter is called the pitch diameter.

  12. Nomenclature of Spur Gear Circular pitch. This is the distance from a point on one tooth to the corresponding point on the adjacent tooth measured along the pitch circle.

  13. Nomenclature of Spur Gear Tooth thickness. This is the distance from a point on one face of tooth to the corresponding point on the adjacent face of the same tooth measured along the pitch circle.

  14. Nomenclature of Spur Gear Module. This is the ratio of the pitch diameter to the number of teeth. The unit of the module should be millimeters (mm). The module is defined by the ratio of pitch diameter and number of teeth.

  15. Nomenclature of Spur Gear Diametral pitch. This is the ratio of the number of teeth to the pitch diameter. Thus, it is the reciprocal of the module. Since diametral pitch is used only with U.S. units, it is expressed as teeth per inch.

  16. Nomenclature of Spur Gear Addendum, a. This is the radial distance from the pitch circle to the outside of the tooth. Dedendum, b. This is the radial distance from the pitch circle to the bottom land.

  17. Nomenclature of Spur Gear Clearance circle. Thisis a circle that is tangent to the addendum circle of the mating gear. Clearance, c. This is the is the amount by which the dedendum in a given gear exceeds the addendum of its mating gear.

  18. Conjugate Action Mating gear teeth acting against each other to produce rotary motion are similar to cams. When the tooth profiles, or cams, are designed so as to produce a constant angular velocity ratio during meshing, these are said to have conjugate action.

  19. Involute Profile Mating gear teeth acting against each other to produce rotary motion are similar to cams. When the tooth profiles, or cams, are designed so as to produce a constant angular velocity ratio during meshing, these are said to have conjugate action. One of these solutions is the involute profile, which, with few exceptions, is in universal use for gear teeth.

  20. Fuandamentals of Gear Design: gear ratio When two gears are in mesh, their pitch circles roll on one another without slipping. Then the pitch-line velocity must be constant. Designate the pitch radii as and and the angular velocities as and , respectively. Gear ratio

  21. Fuandamentals of Gear Design: gear drawing gear layout pressure angle The angle is called the pressure angle, and it usually has values of 20 or 25 degree, with the 20 degree form most widely available.

  22. Fuandamentals of Gear Design: gear drawing

  23. Fuandamentals of Gear Design: gear drawing

  24. Fuandamentals of Gear Design: important parameter

  25. Fuandamentals of Gear Design: important parameter

  26. Fuandamentals of Gear Design: interference (Length of contact) Length of contact Non-standard gear: Standard gear:

  27. Fuandamentals of Gear Design: interference (Length of contact) Interference will occur when or or

  28. Fuandamentals of Gear Design: contact ratio Gears should not generally be designed having contact ratios less than about 1.40, because inaccuracies in mounting might reduce the contact ratio even more, increasing the possibility of impact between the teeth as well as an increase in the noise level. Contact ratio. It is a number that indicates the average number of pairs of teeth in contact. Note that this ratio is also equal to the length of the path of contact divided by the base pitch.

  29. Fuandamentals of Gear Design: interference (Smallest Teeth Number) Interference will occur when the points of tangency of the pressure line with the base circles C and D are located inside of points A and B. The smallest number of teeth on a spur pinion and gear, one-to-one gear ratio, which can exist without interference is where k = 1 for full-depth teeth, 0.8 for stub teeth and = pressure angle.

  30. Fuandamentals of Gear Design: interference (Smallest Teeth Number) Interference will occur when the points of tangency of the pressure line with the base circles C and D are located inside of points A and B. If the mating gear has more teeth than the pinion, that is, is more than one, then the smallest number of teeth on the pinion without interference is given by

  31. Fuandamentals of Gear Design: interference (Smallest Teeth Number) Interference will occur when the points of tangency of the pressure line with the base circles C and D are located inside of points A and B. The largest gear with a specified pinion that is interference-free is

  32. Fuandamentals of Gear Design: interference (Smallest Teeth Number) Interference will occur when the points of tangency of the pressure line with the base circles C and D are located inside of points A and B. The smallest spur pinion that will operate with a rack without interference is

  33. Fuandamentals of Gear Design: Tooth System The smallest spur pinion that will operate with a rack without interference is

  34. Fuandamentals of Gear Design: Tooth System

  35. Fuandamentals of Gear Design: Gear Force Analysis

  36. Fuandamentals of Gear Design: Gear Force Analysis

  37. Fuandamentals of Gear Design: Gear Force Analysis

  38. Fuandamentals of Gear Design: Gear Force Analysis Ex. Ex.

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