Gear Train Velocity Ratios Quiz
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Questions and Answers

What is the purpose of using the spoked design in large spur gears?

  • To save weight (correct)
  • To reduce speed
  • To increase torque
  • To improve gear meshing

    • Why is the illustration of the spoked gear in Figure 8-4(a) missing a keyway?

  • To increase torque transmission
  • To simplify assembly
  • It is a stock item, and the user finishes the bore to match equipment (correct)
  • To lower the production cost

    • What is the purpose of the solid hub design in smaller spur gears?

  • Locking the key in place after assembly (correct)
  • Allowing for gear customization
  • Saving weight
  • Increasing the gear diameter

    • What is the assembly called when spur gear teeth are machined into a straight, flat bar?

    <p>Rack</p> Signup and view all the answers

    Why are gears with diameters between small solid form and larger spoked form often produced with a thinned web?

    <p>To save weight</p> Signup and view all the answers

    What ability does a designer have when creating special gear designs?

    <p>Implementing them into mechanical devices or systems</p> Signup and view all the answers

    What are the preferred units for pitch line speed according to the text?

    <p>m/s</p> Signup and view all the answers

    How is pitch line speed calculated in the Metric Module System?

    <p>$Dn/60,000$</p> Signup and view all the answers

    What is the purpose of developing unit-specific relationships for pitch line speed in the mentioned units?

    <p>To simplify calculations in those units</p> Signup and view all the answers

    Why are certain units preferred for pitch line speed calculations in gear design?

    <p>For consistency in calculations throughout the book</p> Signup and view all the answers

    What is the significance of exercising careful manipulation of units in gear design?

    <p>To ensure accurate calculations</p> Signup and view all the answers

    What is the main function of the pitch circle in gears?

    <p>To ensure smooth engagement of gear teeth</p> Signup and view all the answers

    Which symbol is commonly used to represent the number of teeth in gears?

    <p>N</p> Signup and view all the answers

    What is the purpose of the pitch diameter D in gear calculations?

    <p>To provide a characteristic size for calculations</p> Signup and view all the answers

    Which pitch system is commonly used in the United States?

    <p>Diametral pitch system</p> Signup and view all the answers

    What is important about having identical pitches in mating gears?

    <p>It ensures smooth engagement of gear teeth</p> Signup and view all the answers

    What is another term sometimes used for diametral pitch Pd?

    <p>DP</p> Signup and view all the answers

    In which systems are standard pitches defined?

    <p>Three different systems</p> Signup and view all the answers

    What is the primary function of the number of teeth in a gear?

    <p>To ensure an integer number of teeth in the gear</p> Signup and view all the answers

    What is the relationship between pitch, gears, and their engagement?

    <p>Pitch ensures smooth tooth engagement</p> Signup and view all the answers

    What is the significance of tolerances on critical dimensions in gears and gear trains?

    <p>They ensure precise functioning</p> Signup and view all the answers

    What is the minimum number of teeth required for the pinion in the 141°, 2 full-depth, involute system to ensure no interference?

    <p>32 teeth</p> Signup and view all the answers

    How many teeth are required to avoid interference in the 20°, full-depth, involute system?

    <p>18 teeth</p> Signup and view all the answers

    What is the maximum number of teeth that can be used on the mating gear for a 20°, full-depth system when the pinion has only 17 teeth?

    <p>1309 teeth</p> Signup and view all the answers

    What is the velocity ratio defined as?

    <p>Ratio of input speed to output speed</p> Signup and view all the answers

    Which term refers to the product of the velocity ratios for each gear pair in a gear train?

    <p>Train Value (TV)</p> Signup and view all the answers

    What happens to most gear drives in terms of speed?

    <p>They usually reduce speed</p> Signup and view all the answers

    What is the action equivalent to when two gears are in mesh without slipping?

    <p>Rolling motion</p> Signup and view all the answers

    In a gear train, what is considered the fundamental building block of the total speed change ratio?

    <p>Velocity Ratio (VR)</p> Signup and view all the answers

    What is true about the linear velocity at the pitch point when two gears are in mesh?

    <p>It is equal for both gears</p> Signup and view all the answers

    What is the main difference between a gear train and a gear system?

    <p>Speed Ratio between Input and Output Gears</p> Signup and view all the answers

    What is the most widely used spur gear tooth form mentioned in the text?

    <p>Full-depth involute form</p> Signup and view all the answers

    What geometric curves are gear teeth in mesh based on?

    <p>Conjugate curves</p> Signup and view all the answers

    Why is maintaining a constant angular velocity ratio between two rotating gear teeth important?

    <p>To prevent speeding up and slowing down during engagement</p> Signup and view all the answers

    Which illustration helps visualize an involute curve according to the text?

    <p>A cylinder with a string and pencil</p> Signup and view all the answers

    What does the base circle represent in gear teeth geometry?

    <p>The circle used to draw the involute curve</p> Signup and view all the answers

    What principle of kinematics ensures a constant angular velocity ratio between two rotating bodies?

    <p>Law of gearing</p> Signup and view all the answers

    What AGMA standard is primarily referenced for analytical design methods related to spur and helical gears?

    <p>AGMA 2001-D04 Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth</p> Signup and view all the answers

    'Diametral Pitch System' and 'Metric Module System' are associated with what aspect of gear design?

    <p>'Metric Module System' relates to gear sizing standards</p> Signup and view all the answers

    'Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth' is a standard set by which organization?

    <p>American Gear Manufacturers Association (AGMA)</p> Signup and view all the answers

    What is the equation to compute the equivalent diametral pitch, Pd, for given standard metric modules?

    <p>P = 25.4/m</p> Signup and view all the answers

    What advantage do the final forms of the center distance Equations (8-7) and (8-8) provide according to the text?

    <p>All numbers on the right side are typically integers or exact fractional dimensions</p> Signup and view all the answers

    What causes backlash in gear teeth transmission according to the text?

    <p>Adjusting center distance to a larger value than theoretical</p> Signup and view all the answers

    What is an important design decision related to backlash in gear pairs?

    <p>Balancing cost of production with desired performance</p> Signup and view all the answers

    Which association provides recommendations for backlash in gear standards?

    <p>AGMA: American Gear Manufacturers Association</p> Signup and view all the answers

    What does the pressure angle determine in gear teeth design?

    <p>Size of base circle</p> Signup and view all the answers

    In gear teeth transmission, what does the force transferred from the driver to the driven gear act along?

    <p>&quot;Line of action&quot;</p> Signup and view all the answers

    What is backlash in gear pairs influenced by according to the text?

    <p>Desired precision and size of gears</p> Signup and view all the answers

    What is used to feed the cutter generating the gear teeth more deeply into the gear blank than the theoretical value?

    <p>Center distance adjustment</p> Signup and view all the answers

    What is an inaccurate calculation for center distance caused by according to the text?

    <p>Irrational values used in calculations</p> Signup and view all the answers

    What is the relationship between pitch and tooth size?

    <p>Smaller pitches have larger teeth; larger pitches have smaller teeth.</p> Signup and view all the answers

    What are coarse pitches defined as?

    <p>Pitches under 20</p> Signup and view all the answers

    What does a metric module m of smaller value indicate?

    <p>Smaller teeth</p> Signup and view all the answers

    What is the relation between diametral pitch (Pd) and metric module (m)?

    <p>$Pd = \frac{25.4}{m}$</p> Signup and view all the answers

    Which symbol is sometimes used for module in references and vendors' tables?

    <p>$M$</p> Signup and view all the answers

    What is the center distance defined as?

    <p>$D = \frac{N}{P}$</p> Signup and view all the answers

    What is the face width of a gear?

    <p>Width parallel to the gear axis</p> Signup and view all the answers

    "A module of $m = 1.25$ is closely similar in size to which diametral pitch value?"

    <p>$Pd = 20$</p> Signup and view all the answers

    What is the basic definition of the train value in a gear train?

    <p>The number of teeth in the driven gear divided by the number of teeth in the driving gear</p> Signup and view all the answers

    What is a common feature of an idler gear in a gear train?

    <p>Any pitch diameter size and any number of teeth can be used for an idler gear</p> Signup and view all the answers

    How is an internal gear different from an external gear?

    <p>Internal gears are used when directional rotation needs to be different, while external gears enable same-direction rotation</p> Signup and view all the answers

    What is the purpose of an internal gear in a gear train?

    <p>To maintain the same direction of rotation for input and output gears</p> Signup and view all the answers

    How is the train value calculated for a double-reduction gear train?

    <p>Product of number of teeth in driven gears divided by product of number of teeth in driving gears</p> Signup and view all the answers

    When using an idler gear in a gear train, what effect does it have on the output gear?

    <p>It causes a direction reversal</p> Signup and view all the answers

    What determines whether a train value is considered positive or negative in a gear train?

    <p>The direction of rotation between input and output gears</p> Signup and view all the answers

    What is an idler gear also known as in a gear train?

    <p>Driver-driven gear</p> Signup and view all the answers

    What is a common application for using internal gears?

    <p>Reducing space taken up compared to external gears</p> Signup and view all the answers

    In what scenario would it be essential to express velocity ratio in terms of the numbers of teeth in each gear?

    <p>In design to ensure integer values for velocity ratio</p> Signup and view all the answers

    What is the formula to calculate the base circle diameter for a gear?

    <p>Db = D cos φ</p> Signup and view all the answers

    Which tooth form is considered obsolete in gear design?

    <p>142°</p> Signup and view all the answers

    What defines the term 'contact ratio' in gear operation?

    <p>The ratio of the length of the line-of-action to the base pitch for the gear</p> Signup and view all the answers

    When does interference between gears occur?

    <p>When a small pinion drives a large gear</p> Signup and view all the answers

    What is the minimum recommended contact ratio in typical spur gear combinations?

    <p>1.2</p> Signup and view all the answers

    How can a designer ensure no interference between gears in a given application?

    <p>By increasing the number of teeth in the pinion</p> Signup and view all the answers

    What is the full-depth, involute-tooth form for varying pressure angles?

    <p>142°</p> Signup and view all the answers

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