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 (D)</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 (C)</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 (B)</p> Signup and view all the answers

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

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

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

<p>$Dn/60,000$ (C)</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 (C)</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 (D)</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 (B)</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 (A)</p> Signup and view all the answers

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

<p>N (D)</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 (A)</p> Signup and view all the answers

Which pitch system is commonly used in the United States?

<p>Diametral pitch system (D)</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 (C)</p> Signup and view all the answers

What is another term sometimes used for diametral pitch Pd?

<p>DP (A)</p> Signup and view all the answers

In which systems are standard pitches defined?

<p>Three different systems (D)</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 (A)</p> Signup and view all the answers

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

<p>Pitch ensures smooth tooth engagement (B)</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 (C)</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 (A)</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 (C)</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 (C)</p> Signup and view all the answers

What is the velocity ratio defined as?

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

What happens to most gear drives in terms of speed?

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

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

<p>Rolling motion (C)</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) (C)</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 (B)</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 (C)</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 (A)</p> Signup and view all the answers

What geometric curves are gear teeth in mesh based on?

<p>Conjugate curves (B)</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 (C)</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 (A)</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 (B)</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 (B)</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 (A)</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 (A)</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) (A)</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 (D)</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 (B)</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 (D)</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 (D)</p> Signup and view all the answers

Which association provides recommendations for backlash in gear standards?

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

What does the pressure angle determine in gear teeth design?

<p>Size of base circle (A)</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; (A)</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 (A)</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 (D)</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 (B)</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. (B)</p> Signup and view all the answers

What are coarse pitches defined as?

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

What does a metric module m of smaller value indicate?

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

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

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

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

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

What is the center distance defined as?

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

What is the face width of a gear?

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

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

<p>$Pd = 20$ (D)</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 (C)</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 (B)</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 (C)</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 (B)</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 (A)</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 (C)</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 (A)</p> Signup and view all the answers

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

<p>Driver-driven gear (C)</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 (D)</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 (C)</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 (D)</p> Signup and view all the answers

Which tooth form is considered obsolete in gear design?

<p>142° (B)</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 (C)</p> Signup and view all the answers

When does interference between gears occur?

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

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

<p>1.2 (D)</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 (D)</p> Signup and view all the answers

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

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

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