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Building Mechanisms

Gateway To Technology. Building Mechanisms. Multi-angle photos to help you build. Definitions…. Mechanisms – a change in force or torque. A force is a push or pull in a straight line. Torque is a push or pull in a circular direction. Gear – A rotating machine part with teeth.

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Building Mechanisms

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  1. Gateway To Technology Building Mechanisms Multi-angle photos to help you build

  2. Definitions… Mechanisms – a change in force or torque

  3. A force is a push or pull in a straight line. Torque is a push or pull in a circular direction.

  4. Gear – A rotating machine part with teeth

  5. Gear Train – 2 or more gears connected together to do work.

  6. Torque – Force applied to turn an object

  7. Gear Base Parts needed

  8. Simple Gear Train Driven Drive 1. Input and Output Shafts are parallel or perpendicular 2. A- Speed is decreased, constant, or increased? 3. B – Speed is decreased, constant, or increased? 4. A - Torque is constant or increased? 5. B – Torque is decreased or increased? 6. A – Gear Ratio is __ : __ 7. B – Gear Ratio is __ teeth:__ teeth or 3:5 9. Flow of Power is ____________. 10. Is gear direction reversible? A. Driven Drive B.

  9. Simple Gear Train with Idler Drive Idler Driven

  10. Bevel Gear • Can be found in: • Hand drill • Car differential • Shaft-driven bicycle

  11. Chain Drive 2. Angle is parallel 3. Speed is increased or decreased? 4. Torque is increased or decreased? 5. Ratio 18:30 or __ : __ 6. Smaller drive gear – Speed – decreased Torque - increased 7. Shaft direction same Drive Driven

  12. Where Do You Find a Chain and Sprocket? 9. Advantage of Chain and Sprocket over spur gears: Transfer torque and speed over long distances • 8. Found in: • _______ • _______

  13. Rack and Pinion Pinion Rack

  14. Where Do You Find a Rack and Pinion? • Used to convert between rotary and linear motion. • Provides gear reduction to make it easier to turn the wheels. • 7. Used in steering systems of cars to convert rotary motion of steering wheel to the side to side motion in the wheels. • Rack and pinion steering Pinion Rack

  15. Universal Joint • Angular Range > 90˚ and < 270˚ 2. Speed and Torque constant 3. Ratio 1:1 4. Flow of Power reversible 5. Input & Output Shafts same direction

  16. Where Can You Find a Universal Joint? • Drive shaft of vehicles • Power take-off Universal joints are used to transmit rotary movement at an angle that is not 90°. www.rqriley.com/imagespln/pattersn_ujoint.jpg

  17. Worm and Wheel 1. 90˚ Angle 2. Speed is ________ 3. Torque is increased 5. Gear Ratio ___:___ 6. Flow of Power is NOT reversible 7. Direction of Travel reversible Wheel Worm

  18. Where Do You Find a Worm and Wheel? • A worm is used to reduce speed and increase torque. • The motion is not reversible; a gear cannot drive a worm. • 8. Found in: • Tuning mechanism on string instruments • Electric motors • Winch

  19. Crank and Slider 1. Input Movement- rotary 2. Output Movement reciprocating 3. Slider Moves 2 in. (or diameter of crank) 4. Increased Crank increased distance slider moves 5. Flow of Power is not reversible Crank Slider

  20. Where Do You Find a Crank and Slider? 7. Found in: • Steam train • Internal combustion engine

  21. Cam and Follower 2. Input Movement rotary 3. Output Movement reciprocating 4. Follower moves up and down 1 time for every revolution of the crank 5. Flow of Power not reversible 6. Direction of Travel not reversible FOLLOWER CAM

  22. Where Do You Find a Cam and Follower? • 7. Found in: • Cam shaft • As a cam rotates, the flat follower is raised and lowered, converting rotary motion to reciprocating (back and forth) motion. • The cam pictured here would be reversible, as it is symmetrical.

  23. Leadscrew 1. Input Movement rotary or linear 2. Output Movement rotary or linear 3. Revolutions 4.75 4. Flow of Power Not reversible 5. Force is increased 6. Direction of Travel reversible?

  24. Where Do You Find a Lead Screw? • Changes rotary movement into linear movement • Significantly increases force • A person can put a little force into turning the handle to move a heavy car. • Jack • Vice

  25. Belt Drive 2. Shafts parallel 3. Speed constant 4. Torque constant 5. Ratio 1:1 6. Larger drive pulley Speed – increased Torque - decreased 7. Open belt – same direction 8. Crossed belt - opposite Drive Driven

  26. Where Do You Find a Pulley and Belt? • 9. Found in: • Lawn mower • Car engine BELTS • 10. Belts instead of chains: • Quieter • Less expensive

  27. Differential Gear • Gears used – Bevel • Axles turn – Same direction • Used in – Vehicles • Purpose – Wheels spin at different speeds when turning Howstuffworks.com/differential

  28. Simple Gear Train Bevel Gear Found in: • Watch • Sewing Machine • Motor • Found in: • Tuning mechanism • on string instruments • Electric motors • Winch Gear with Idler Worm and Wheel Found in: - Paper Transport Rollers • Found in: • Jack • Vice Bevel Gear Belt & Pulley Found in: • Hand drill • Car differential • Shaft-driven bicycle • Found in: • Lawn mower • Car engine

  29. Resources Microsoft, Inc. (2008). Clip Art. Retrieved from http://office.microsoft.com/en-us/clipart/default.aspx Mr. Jopp. (2015). http://www.mrjopp.com/

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