CHAPTER 20 GEARING AND CAMS

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CHAPTER 20GEARING AND CAMS

• INSTRUCTOR M.YAQUB

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20.1 Gears

• Gears are used to transmit power and rotating or
  reciprocating motion from one machine part to
  another.
• Few gears are given in the next slide.

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20.2 Spur Gear (For Parallel shaft)

• A friction wheel can be used to transmit power
  from one shaft to anther parallel shaft.
• It may have slip and a large pressure is required
  to avoid the slip.
• If teeth are provided on the surface, pressure
  can be reduces and no slip. It become a spur
  gear.

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• Linear velocity (pi) D n, it must be same for
  both gear to avoid relative motion.
• Hence

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SPUR GEAR
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20.4 The shape of the tooth

• For minimum noise and smooth operation, the
  curved surface of the tooth profile must be a
  definite geometric form, the most common is
  involute profile.
• Pressure angle is important usually two pressure
  angle, 14.5 and 20 degree.

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How to construct a base circle
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Worm Gear

• For non parallel and non intersecting shaft

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Bevel Gear (For intersecting shaft)
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