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