Ch9 Gears

Epicyclic or Planetary Gears
- annulus: outer ring gear which meshes with the planet gears
- carrier: movable arm
- 2 DOF
- system requires control of 2 inputs to produce 1 output
- high torque output
- load shared equally across planet gears means longer life for each
- total motion of any gear is sum of motion of arm and motion of gear with respect to arm
- if arm were stationary would get a simple gear train
- => all motion relative to arm is analyzed as simple gear train
Differential Mechanism
- receives 1 input and produces 2 outputs
- designed to drive a pair of wheels with equal torque while allowing them to rotate at different speeds
- a vehicles wheels rotate at different speeds especially when turning corners
- when turning outside wheel rotates faster and inside wheel rotates slower
Fundamental Law of Gearing
- The angular velocity ratio m_v is constant at all positions
- The torque ratio m_T is constant at all positions
- Gear tooth contours on mating teeth must be conjugates (involute curve)
Involute Curve

size of teeth must be the same for gears to mesh

Author

sep293

84959

Card Set

Ch9 Gears

Description

Mechanisms Final

Updated

5/10/2011, 6:04:45 AM

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