Gears

Question 1

What are gears used for?

Answer 1

To transmit force and motion (rotary or linear)

Question 2

What do gears do?

Answer 2

Connect shafts by using a gear train, reduce speed and increase torque by using a reduction unit, increase speed by using an overdrive unit

Question 3

Where is the pitch line in a gear?

Answer 3

The pitch line is the line of contact between the two cylinders

Question 4

What does addendum (add) stand for?

Answer 4

The part of a tooth that lies between the pitch circle and the outside diameter of a gear

Question 5

Define Dedendum( ded)

Answer 5

The part of the tooth that lies between the pitch circle and the root diameter of a gear

Question 6

Define Clearance (cl)

Answer 6

The gap between the working depth and the whole depth

Question 7

Define circular pitch

Answer 7

The distance between two corresponding points on adjacent teeth, measured on the pitch circle

Question 8

Define outside diameter (Od)

Answer 8

The total number of teeth on the gear divided by the pitch diameter in inches

Question 9

Pitch diameter (Pd)

Answer 9

The diameter of the pitch circle

Question 10

Working depth (wkd)

Answer 10

The depth of a tooth engagement of two meshing gear teeth

Question 11

Whole depth (whd)

Answer 11

The total height of a tooth or the total depth of a tooth space

Question 12

Chordal thickness (tooth tickness)

Answer 12

The thickness of the tooth (at the pitch circle) on the face of the gear

Question 13

What are the two most common pressure angles?

Answer 13

14.5° and 20°

Question 14

What is pressure angle?

Answer 14

In the angle of gear tooth

Question 15

What gear is this?

Answer 15

Spur gear

Question 16

Answer 16

External Spur gear

Question 17

Answer 17

Internal Spur gear

Question 18

Answer 18

Rack and pinion

Question 19

Answer 19

Single helical gear

Question 20

Answer 20

Double helical gears

Question 21

Answer 21

Herring bore gear

Question 22

Answer 22

Bevel gear

Question 23

Answer 23

Hyped gear

Question 24

Answer 24

Worm gear

Question 25

What is direct drive?

Answer 25

When input speed of the gearbox is same as output speed

Question 26

Drive gear is

Answer 26

The input gear of the gear train that turns the mating gear

Question 27

Driver gear is

Answer 27

Output gear in the gear train that the drive gear forces to turn

Question 28

Speed reducer is-

Answer 28

A gear train with a slower output speed than input

Question 29

What are examples of gear wear?

Answer 29

Lack of lubrication
Abrasives in the gear train
Incorrect tooth contact
Extended heavy loads

Question 30

What is backlash

Answer 30

The clearance between the gear teeth at the pitch line approximately halfway up the tooth face

Question 31

What does backlash do?

Answer 31

Keeps teeth from binding and allows room for thermal expansion and for a lubricating film

Question 32

What do gears need to mesh correctly?

Answer 32

Same diametral pitch
Same pressure angle of gear teeth
Correct hand of gear (unless they are straight teeth)
Shafts in correct position
Same helix angle

Question 33

What is an idler gear?

Answer 33

Change the direction of rotation or keep it the same (doesn’t effect gear ratio)

Question 34

Three parts of a sun gear

Answer 34

Ring gear, Sun gear, carrier with mounted planet gears

Question 35

Methods of checking gear meshing?

Answer 35

Prussian blue
Venétain red (orange paste)
Black light
Pencil lead

Question 36

How to check backlash?

Answer 36

Dial indicator
Lead wire (deformed between teeth)
Using feeler gages manually fitted between mating gears)

Question 37

When checking blashlash what must you ensure?

Answer 37

Components parts are clean