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ECT 459 PowerPoint Presentation

ECT 459

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ECT 459

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Presentation Transcript

  1. ECT 459 Lecture 6 Mechanical Mechanisms

  2. Mechanism Overview Actuator Motion Transmitters Change Speed Change Torque Categories Rotary-Rotary Rotary-Translational Cyclic Motion

  3. Rotary-Rotary Gears pitch # of teeth gear ratio bevel efficiency backlash stiffness break-away friction back driveability direction

  4. Rotary-Rotary Belts - Pulleys diameter ratios direction toothed pulley (timing belt)

  5. Rotary-Translational Lead Screw or Ball Screw backlash pitch vs lead rev/in vs in/rev Worm Gear back drivability Rack – Pinion pitch Belt – Pulley

  6. Cyclic Motion Slider – Crank piston engine Four-Bar windshield wipers forklift Linkages

  7. Cyclic Motion Cams input shaft cam follower eccentricity rise fall dwell pressure angle radius of curvature

  8. Flexible Couplings Couplers torque stiffness axial alignment shaft diameters bellow helical spider

  9. Actuator Sizing Maximum Torque Rated Torque Maximum Speed Resolution Horsepower Power Loss (friction)

  10. Degrees of Freedom X Y Z A B C Roll pitch yaw Spherical coordinates