Gears Study Guide
In spur gear terminology the play between mating teeth is called: a. Backlash b. Clearance c. Tooth relief d. Working space
A. Backlash
In worm gearing, _______ withstands high sliding velocity in contact with a steel worm better than other materials. a. Copper b. Aluminum c. Titanium d. Lead
A. Copper
_______ gear speed reducers are used to obtain speed reduction up to 100:1 with only one set of gears. a. Worm b. Hypoid c. Helical d. Bevel
A. Worm
List all organizations that establish standards for both gears and enclosed drives.
ANSI, AGMA, ISO, and DIN
Which one of the following is an organization that establishes standards for both gears and enclosed drives? a. TSI b. ANSI c. DTN d. ANSH
B. ANSI
Most enclosed drives are used to: a. Increase speed and output torque. b. Increase speed and reduce output torque. c. Reduce speed and output torque. d. Reduce speed and increase output torque.
B. Increase speed and reduce output torque
Worm-gear drives are referred to as: a. Speed drives b. Right-angle drives c. Left-angle drives d. Combination drives
B. Right-angle drives
The efficiency of these gears tends to be lower than other gear types: a. Helical b. Worm c. Hypoid d. Bevel
B. Worm
Speed Reducers can be: a. Base-mounted b. Shaft-mounted c. A and b above d. None of the above
C. A and B above
Nonferrous gear materials include: a. Ductile iron b. Sintered powder metal c. Bronze (copper alloy) d. Carbon steel
C. Bronze (copper alloy)
Ferrous gear materials include: a. Copper b. Aluminum c. Cast iron d. Zinc
C. Cast iron
In spur gear terminology the height of a tooth above a pitch circle is called: a. Dedendum b. Addendum c. Diametral pitch d. Circular pitch
C. Diametral Pitch
In a Q8 A-HA-14 gear, the HA is the: a. Quality number b. Tooth thickness tolerance code c. Material designation d. Hardness designation
C. Material Designation
Which of the following gear design categories does not belong in the list? a. Spur b. Helical c. Worm d. Ground
D. Ground
_______ gears are like spiral gears except the teeth are not curved. a. Cycloidal tooth b. Internal tooth c. Hypoid tooth d. Skew tooth
D. Skew tooth
List five categories of gear tooth failure.
Wear, surface fatigue, plastic flow, breakage, and process-related failures
What are eight major factors to consider when selecting gears?
diametral pitch, tooth size, pitch diameter, gear size, pressure angle, tooth shape, and shaft size
Bronzes account for most ferrous gears. a. True b. False
false
Double helical gear sets use two pair of opposed gear teeth to eliminate thrust load. a. True b. False
false
Enclosed gear speeds are generally limited to 1,200 rpm. a. True b. False
false
Face gears are used mostly to transmit motion and heavy loads. a. True b. False
false
Gears are still quite useful even after 1 or 2 teeth have broken. a. True b. False
false
Gears can only be lubricated using oil. a. True b. False
false
Helical gears tend to have low efficiencies into the 60 percent to 70 percent range. a. True b. False
false
Hypoid gears are stronger than spiral gears but are much noisier due to their high contact ratio. a. True b. False
false
The most commonly used gear plastics are polypropylene, polyamid, and phenolic. a. True b. False
false
The shape of spur gear teeth is based on an involute form which produces a sliding contact rather than a rolling contact between mating teeth. a. True b. False
false
The side of a spur gear tooth is called a tooth surface. a. True b. False
false
The simplest and most common bevel gear is the spiral. a. True b. False
false. Straight bevel
Gears supplied as assembled are referred to as open gearing. a. True b. False
false. Unassembled
Describe where internal gears are typically used.
planetary gear systems
A breather is a plug with a hole that permits air flow inside a gearbox. a. True b. False
true
Cycloidal gearing is unique in that all torque transmitting parts roll rather than grind. a. True b. False
true
Gears used to transmit power through right angles on nonintersecting shafts are called worm gears. a. True b. False
true
Hypoid gear shaft axes do not intersect. a. True b. False
true
Inadequate lubrication of gears will cause undo wear. a. True b. False
true
Plastic gears work well in corrosive environments. a. True b. False
true
Skew tooth gears are like spiral gears except the teeth are not curved. a. True b. False
true
The efficiency of worm gears tends to be lower than other gear types. a. True b. False
true
The teeth of herringbone gears join in the middle. a. True b. False
true
When ordering gears, diametral pitch, tooth size, pitch diameter, gear size, pressure angle, tooth shape, and shaft size should be specified. a. True b. False
true
Worm-gear speed reducers are used to obtain speed reduction up to 100:1 with only one set of gears. a. True b. False
true
List two types of lubrication.
Oil and Grease
What are four advantages of traction drives?
Rely on friction to convey torque from the input to the output include flat disk type and ball and cone.
List seven different types of gearing (speed reduction).
Spur, helical or double helical, straight bevel, spiral bevel, cylindrical worm, double-enveloping worm, and hypoid