3 gear drives

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3 gear drives

  1. 1. GEARS AND GEAR DRIVES • IT IS A TOOTHED WHEEL WITH TEETH CUT ON ITS PHERIPHERY. •POWER OR MOTION IS TRANSMITTED FROM ONE SHAFT TO ANOTHER WITH GEAR DRIVE. SLIDE 1
  2. 2. WHEN GEAR DRIVES ARE USED? 1. CENTER DISTANCE ARE RELATIVELY SHORT 2. SPEED OF THE SHAFT IS LOW 3. POSITIVE DRIVE IS NECESSARY I.e VELOCITY RATIO IS FIXED AND KNOWN WITH CERTAINTY 4. NEED TO STEP UP OR STEP DOWN THE SPEED 5. HIGH TORQUE IS TRANSMITTED 6. PRECISE TIMING IS REQUIRED SLIDE 2
  3. 3. DISADVANTAGES OF GEAR DRIVES 1. WHOLE SET IS EFFECTED IF ONE TOOTH GETS DAMAGED 2. MANUFACTURING OF GEARS REQUIRES SPECIAL TOOLS AND EQUIPMENT. SLIDE 3
  4. 4. TYPES OF GEARS 1. 2. 3. 4. 5. 6. 7. SPUR GEAR HELICAL GEAR BEVEL GEAR SPIRAL GEAR WORM GEAR RACK AND PINION INTERNAL AND EXTERNAL GEARING SLIDE 4
  5. 5. SPUR GEAR 1. IT IS A CYLINDRICAL GEAR 2. TOOTH TRACES ARE STRAIGHT LINES AND PARALLEL TO THE GEAR AXIS 3. USED FOR TRANSMITTING OF MOTION BETWEEN TWO SHAFTS WHOSE AXIS ARE PARALLEL AND COPLANAR 4. THESE GEARS HAVE HIGH (96-98%) EFFICIENCY 5. FREE FROM AXIAL THRUST DURING TOOTH ENGAGEMENT. SLIDE 5
  6. 6. APPLICATIONS OF SPUR GEAR • USED AS A SLIDING GEARS FOR SPEED CHANGING MECHANISM IN GEAR BOXES OF LATHE. SLIDE 6
  7. 7. DIS ADVANTAGE OF SPUR GEAR 1. MORE NOISY 2. WEAR OUT READILY 3. DEVELOP BACKLASH SLIDE 7
  8. 8. HELICAL GEAR 1. CYLINDRICAL GEAR TOOTH 2. TOOTH TRACES ARE STRAIGHT HELICES AND INCLINED AT ANGLE TO THE GEAR AXIS. SLIDE 8
  9. 9. APPLICATIONS OF HELICAL GEAR 1. AUTOMOBILE GEAR BOXES 2. STEAM AND GAS TURBINE FOR SPEED REDUCTION. SLIDE 9
  10. 10. 1. BEVEL GEAR BEVEL GEAR WHEELS CONFORM TO THE FRUSTA OF CONES HAVING A COMMON VERTEX. 2.TOOTH TRACES ARE STRAIGHT LINE GENARATORS OF THE CONE. 3.USED CONNECT TWO SHAFTS WHOSE AXIS ARE CO – PLANAR BUT INTERSECTING. 4. WHEN THE SHAFTS ARE AT RIGHT ANGLES AND THE WHEELS ARE EQUAL IN SIZE THESE ARE CALLED AS “MITRE GEARS”. 5. IF TEETH INCLINED TO THE FACE OF THE BEVEL THESE ARE CALLED AS “HELICAL BEVEL GEARS”. SLIDE 10
  11. 11. APPLICATION OF THE BEVEL GEAR SLIDE 11
  12. 12. SPIRAL GEAR •THESE ARE IDENTICAL TO HELICAL GEARS WITH POINT CONTACT RATHER THAN LINE CONTACT. •GEARS USED WHEN CONNECTION IS TO BE MADE BETWEEN INTERSECTING AND CO-PLANAR SHAFTS. SLIDE 12
  13. 13. WORM GEAR •CONSISTS OF A WORM WHICH IS BASICALLY PART OF SCREW. •USED TO CONNECTING TWO NON-PARALLEL,NON INTERSECTING SHAFTS USUALLY AT RIGHT ANGLES. •GEAR SYSTEM IS SMOOTH AND QUIET IN OPERATION AND PROVIDES HIGH GEAR RATIO. SLIDE 13
  14. 14. APPLICATION OF WORM GEAR •ROTATING SPEED OF THE WORM IS QUIET HIGH COMPARED TO THAT OF WHEEL •RECOMMENDE WHEN HIGH SPEED REDUCTION IS REQUIRED(10:1) SLIDE 14
  15. 15. RACK AND PINION RACK IS A STRAIGHT LINE SPUR GEAR OF INFINITE DIAMETER IT MESHES BOTH INTERNALLY AND EXTERNALLY WITH A CIRCULAR WHEEL CALLED PINION SLIDE 15
  16. 16. APPLICATION OF RACK AND PINION RACK IS A STRAIGHT LINE SPUR GEAR OF INFINITE DIAMETER. •IT MESHES BOTH INTERNALLY AND EXTERNALLY WITH A CIRCULAR WHEEL CALLED PINION. •ARRANGEMENT FINDS APPLICATION WHERE LINEAR MOTION IS TO BE CONVERTED IN TO ROTARY MOTION. SLIDE 16
  17. 17. INTERNAL AND EXTERNAL GEARING •TWO TOOTHED WHEELS ON PARALLEL SHAFTS MAY GEAR EITHER EXTERNALLY OR INTERNALLY. •IN EXTERNAL GEARING ,THE MOTION OF THE TWO WHEELS IS UNLIKE I.e OPPOSITE DIRECTION. •THE LARGER WHEEL OF THE GEAR SYSTEM IS KNOWN AS SPUR AND THE SMALLER WHEEL AS PINION. SLIDE 17
  18. 18. INTERNAL GEARING •THE MOTION OF THE TWO WHEELS IS ALIKE . BOTH ROTATE IN THE SAME DIRECTION. •THE EXTERNAL LARGE WHEEL IS CALLED ANNULAR WHEEL AND THE SMALL INTERNAL WHEEL AS PINION. SLIDE 18
  19. 19. GEAR TERMINOLOGY 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. ADDENDUM: DEDENDUM: FACE WIDTH: TOOTH FACE: TOOTH SPACE: FACE: ADDENDUM CIRCLE: FLANK: FACE: PITCH SURFACE ELEMENT: TOP LAND: ROOT OR DEDENDUM CIRCLE: CLEARANCE: CIEARANCE OR WORKING DEPTH CIRCLE: TOOL THICKNESS: TOTAL WIDTH: CIRCULAR PITCH: SLIDE 19

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