75 Questions
What is the purpose of using the spoked design in large spur gears?
To save weight
Why is the illustration of the spoked gear in Figure 8-4(a) missing a keyway?
It is a stock item, and the user finishes the bore to match equipment
What is the purpose of the solid hub design in smaller spur gears?
Locking the key in place after assembly
What is the assembly called when spur gear teeth are machined into a straight, flat bar?
Rack
Why are gears with diameters between small solid form and larger spoked form often produced with a thinned web?
To save weight
What ability does a designer have when creating special gear designs?
Implementing them into mechanical devices or systems
What are the preferred units for pitch line speed according to the text?
m/s
How is pitch line speed calculated in the Metric Module System?
$Dn/60,000$
What is the purpose of developing unit-specific relationships for pitch line speed in the mentioned units?
To simplify calculations in those units
Why are certain units preferred for pitch line speed calculations in gear design?
For consistency in calculations throughout the book
What is the significance of exercising careful manipulation of units in gear design?
To ensure accurate calculations
What is the main function of the pitch circle in gears?
To ensure smooth engagement of gear teeth
Which symbol is commonly used to represent the number of teeth in gears?
N
What is the purpose of the pitch diameter D in gear calculations?
To provide a characteristic size for calculations
Which pitch system is commonly used in the United States?
Diametral pitch system
What is important about having identical pitches in mating gears?
It ensures smooth engagement of gear teeth
What is another term sometimes used for diametral pitch Pd?
DP
In which systems are standard pitches defined?
Three different systems
What is the primary function of the number of teeth in a gear?
To ensure an integer number of teeth in the gear
What is the relationship between pitch, gears, and their engagement?
Pitch ensures smooth tooth engagement
What is the significance of tolerances on critical dimensions in gears and gear trains?
They ensure precise functioning
What is the minimum number of teeth required for the pinion in the 141°, 2 full-depth, involute system to ensure no interference?
32 teeth
How many teeth are required to avoid interference in the 20°, full-depth, involute system?
18 teeth
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?
1309 teeth
What is the velocity ratio defined as?
Ratio of input speed to output speed
Which term refers to the product of the velocity ratios for each gear pair in a gear train?
Train Value (TV)
What happens to most gear drives in terms of speed?
They usually reduce speed
What is the action equivalent to when two gears are in mesh without slipping?
Rolling motion
In a gear train, what is considered the fundamental building block of the total speed change ratio?
Velocity Ratio (VR)
What is true about the linear velocity at the pitch point when two gears are in mesh?
It is equal for both gears
What is the main difference between a gear train and a gear system?
Speed Ratio between Input and Output Gears
What is the most widely used spur gear tooth form mentioned in the text?
Full-depth involute form
What geometric curves are gear teeth in mesh based on?
Conjugate curves
Why is maintaining a constant angular velocity ratio between two rotating gear teeth important?
To prevent speeding up and slowing down during engagement
Which illustration helps visualize an involute curve according to the text?
A cylinder with a string and pencil
What does the base circle represent in gear teeth geometry?
The circle used to draw the involute curve
What principle of kinematics ensures a constant angular velocity ratio between two rotating bodies?
Law of gearing
What AGMA standard is primarily referenced for analytical design methods related to spur and helical gears?
AGMA 2001-D04 Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth
'Diametral Pitch System' and 'Metric Module System' are associated with what aspect of gear design?
'Metric Module System' relates to gear sizing standards
'Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth' is a standard set by which organization?
American Gear Manufacturers Association (AGMA)
What is the equation to compute the equivalent diametral pitch, Pd, for given standard metric modules?
P = 25.4/m
What advantage do the final forms of the center distance Equations (8-7) and (8-8) provide according to the text?
All numbers on the right side are typically integers or exact fractional dimensions
What causes backlash in gear teeth transmission according to the text?
Adjusting center distance to a larger value than theoretical
What is an important design decision related to backlash in gear pairs?
Balancing cost of production with desired performance
Which association provides recommendations for backlash in gear standards?
AGMA: American Gear Manufacturers Association
What does the pressure angle determine in gear teeth design?
Size of base circle
In gear teeth transmission, what does the force transferred from the driver to the driven gear act along?
"Line of action"
What is backlash in gear pairs influenced by according to the text?
Desired precision and size of gears
What is used to feed the cutter generating the gear teeth more deeply into the gear blank than the theoretical value?
Center distance adjustment
What is an inaccurate calculation for center distance caused by according to the text?
Irrational values used in calculations
What is the relationship between pitch and tooth size?
Smaller pitches have larger teeth; larger pitches have smaller teeth.
What are coarse pitches defined as?
Pitches under 20
What does a metric module m of smaller value indicate?
Smaller teeth
What is the relation between diametral pitch (Pd) and metric module (m)?
$Pd = \frac{25.4}{m}$
Which symbol is sometimes used for module in references and vendors' tables?
$M$
What is the center distance defined as?
$D = \frac{N}{P}$
What is the face width of a gear?
Width parallel to the gear axis
"A module of $m = 1.25$ is closely similar in size to which diametral pitch value?"
$Pd = 20$
What is the basic definition of the train value in a gear train?
The number of teeth in the driven gear divided by the number of teeth in the driving gear
What is a common feature of an idler gear in a gear train?
Any pitch diameter size and any number of teeth can be used for an idler gear
How is an internal gear different from an external gear?
Internal gears are used when directional rotation needs to be different, while external gears enable same-direction rotation
What is the purpose of an internal gear in a gear train?
To maintain the same direction of rotation for input and output gears
How is the train value calculated for a double-reduction gear train?
Product of number of teeth in driven gears divided by product of number of teeth in driving gears
When using an idler gear in a gear train, what effect does it have on the output gear?
It causes a direction reversal
What determines whether a train value is considered positive or negative in a gear train?
The direction of rotation between input and output gears
What is an idler gear also known as in a gear train?
Driver-driven gear
What is a common application for using internal gears?
Reducing space taken up compared to external gears
In what scenario would it be essential to express velocity ratio in terms of the numbers of teeth in each gear?
In design to ensure integer values for velocity ratio
What is the formula to calculate the base circle diameter for a gear?
Db = D cos φ
Which tooth form is considered obsolete in gear design?
142°
What defines the term 'contact ratio' in gear operation?
The ratio of the length of the line-of-action to the base pitch for the gear
When does interference between gears occur?
When a small pinion drives a large gear
What is the minimum recommended contact ratio in typical spur gear combinations?
1.2
How can a designer ensure no interference between gears in a given application?
By increasing the number of teeth in the pinion
What is the full-depth, involute-tooth form for varying pressure angles?
142°
Test your knowledge on gear train velocity ratios and train value calculations. Learn about how to compute the train value in a gear train with different stages of reduction. Explore the various forms of velocity ratios for gear systems.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
