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ECT 459. Lecture 6 Mechanical Mechanisms. Mechanism Overview. Actuator Motion Transmitters Change Speed Change Torque Categories Rotary-Rotary Rotary-Translational Cyclic Motion. Rotary-Rotary. Gears pitch # of teeth gear ratio bevel efficiency backlash stiffness
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ECT 459 Lecture 6 Mechanical Mechanisms
Mechanism Overview Actuator Motion Transmitters Change Speed Change Torque Categories Rotary-Rotary Rotary-Translational Cyclic Motion
Rotary-Rotary Gears pitch # of teeth gear ratio bevel efficiency backlash stiffness break-away friction back driveability direction
Rotary-Rotary Belts - Pulleys diameter ratios direction toothed pulley (timing belt)
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
Cyclic Motion Slider – Crank piston engine Four-Bar windshield wipers forklift Linkages
Cyclic Motion Cams input shaft cam follower eccentricity rise fall dwell pressure angle radius of curvature
Flexible Couplings Couplers torque stiffness axial alignment shaft diameters bellow helical spider
Actuator Sizing Maximum Torque Rated Torque Maximum Speed Resolution Horsepower Power Loss (friction)
Degrees of Freedom X Y Z A B C Roll pitch yaw Spherical coordinates