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  1. 1. MECHANISMS <br />MechanismsbyÁngeles Puebla<br />
  2. 2. Flat Pulleys and Flat Belt<br />PulleySystem<br />Thisbelt reduces slippage. Itisused in car engines. <br />Changingthedirection of motion<br />
  3. 3. ToothedPulleys and ToothedBelt<br />Toothedpulleysavoidslippage.<br />Toothedpulleys and toothedbelts are usedto drive thecamshaft in car engines.<br />Toothedpulleyssystem in therear of a motorcycle<br />
  4. 4. Axle and Shaft<br />
  5. 5. Sprockets and chain<br />Driver sprocket.<br />Pedal.<br />Drivensprocket. Wheel.<br />
  6. 6. Gears<br />Bothintermediategears are linkedtothesameshaft and rotate at thesamespeed.<br />Threegeartrain<br />
  7. 7. SpurGears<br />Spur gears mesh in the same plane. <br />Their teeth are parallel to the rotary shaft.<br />When two spur gears are meshed, they rotate in opposite directions.<br />
  8. 8. SpurGears in motion<br />Whentwospurgears are meshed, thegearsrotate in oppositedirections.<br />
  9. 9. HelicalGears<br />Single helicalgears<br />Helical gears are used for applications that require very quiet and smooth motion at high rotational velocities. <br />Double helical gears transmit torque and smooth motion at very high rotational velocities.<br />Doublehelicalgears<br />aka<br />Herringbonegears<br />
  10. 10. CrossedHelicalGears<br />Crossed Helical gears transmit torque and motion between right angle shafts. <br />Both shafts are situated in parallel planes. <br />These gears rotate smoother and at higher speed than spur gears.<br />
  11. 11. BevelGears<br />Bevel gears have teeth cut on a cone instead of a cylinder.<br />Bevel gears transmit torque and rotary motion between right angle shafts.<br />
  12. 12. Worm and Worm Wheel<br />A worm is a gear with one tooth. The tooth is in the form of a screw thread.<br />A worm wheel meshes with the worm. The worm wheel is a helical gear with teeth inclined so that they can mesh with the worm’s thread. <br />These gears transmit torque and rotary motion between right angle shafts situated in parallel planes (just like crossed helical gears).<br />The worm always drives the worm wheel and never the other way round.<br />The mechanism blocks if the worm wheel tries to drive the worm.<br />Worms are very quiet running.<br />Wormgears are used in guitar tuning machines.<br />
  13. 13. Rack and Pinion<br />►Rack and Pinion Gears transform rotary motion into linear and vice versa.<br />► The pinion is a spur gear with rotary motion.<br />► The rack is a straight bar with teeth straight. Its motion is linear.<br />► Rotating a pinion produces a linear motion of the rack. <br />► Alternately, moving the rack causes rotation in the pinion.<br />
  14. 14. Rack and Pinion<br />Rack and Pinionconvertrotarymotioninto linear motionwhenthe motor is in thepinion.<br />Rack and Pinionconvert linear motionintorotarymotionwhenthe motor is in the rack.<br />
  15. 15. WhoisWho?<br />Identify 4 types of gearswithinthispicture:<br /><ul><li>Spurgears.
  16. 16. Bevelgears.
  17. 17. Helicalgears.
  18. 18. Rack and Pinion.</li></li></ul><li>COMPOUNDGEAR TRAIN<br />Mechanism 1<br />Mechanism 2<br />Thiscompoundgeartrain has 4 gears.<br />B and C are linkedgears.<br />Thisis a SPEEDREDUCER. <br />Thiscompoundgeartrain has 4 gears.<br />B and C are linkedgears.<br />Thisis a SPEEDMULTIPLIER.<br />
  19. 19. Formulas<br />ForPulleys and Beltproblems:<br />nA·ΦA= nB·ΦB<br />nA: rotationalspeed of driver pulley A. Unit: rpm (revolutions per minute).<br />ΦA: diameter of driver pulley A. Unit: cm or mm.<br />nB : rotationalspeed of drivenpulley B. Unit: rpm (revolutions per minute).<br />ΦB : diameter of drivenpulley B. Unit: cm or mm.<br />ForSprockets and ChainProblems:<br />nA·zA= nB·zB<br />nA: rotationalspeed of driver sprocketA. Unit: rpm (revolutions per minute).<br />zA: number of teethof driver sprocketA. <br />nB : rotationalspeed of drivensprocketB. Unit: rpm (revolutions per minute).<br />zB: number of teethof drivensprocketB. <br />ForGearsProblems:<br />nA·zA= nB·zB<br />nA: rotationalspeed of driver gearA. Unit: rpm (revolutions per minute).<br />zA: number of teethof driver gearA. <br />nB : rotationalspeed of drivengearB. Unit: rpm (revolutions per minute).<br />zB: number of teethof drivengearB. <br />MechanismsbyÁngeles Puebla<br />