HET 4 Gearing Principles

Question 1

3 types of gears

Answer 1

Straight cut (spur gear) (Radial)

Helical cut

Double helical (Herringbone)

Question 2

True or false:
Gear teeth may be parallel or tapered with one large end and one small end

Answer 2

True

Question 3

Name 4 distinctive quadrants of a gear tooth

Answer 3

Face
Flank
Heal
Toe

Question 4

The gear pitch line divides what gear tooth areas

Answer 4

Face and Flank

Question 5

Gap between tip of one gear tooth and root of opposite gear

Answer 5

Clearance

Question 6

Why do some angle drive gear sets need to be timed

Answer 6

For consistent Wear Pattern

Longevity

Noise

Question 7

3 types of gear configurations

Answer 7

Reduction

Overdrive

Direct drive

Question 8

If a gear set has a 4:1 ratio, which member is turning at 4 revolutions

Answer 8

Drive (Input) member

Question 9

What would a reduction ratio look like

a) 0.10:1
b) 1.00:1
c) 10.00:1
d) 1.00:2

Answer 9

c) 10.00:1

Question 10

What does an idler gear do

Answer 10

Change direction of driven gear

Allows reverse to be possible

Does not effect speed or torque

Question 11

3 types of tooth designs

Answer 11

Straight cut (Spur) (Radial)

Helical cut

Double helical (Herringbone)

Question 12

Common gear set where internal gears are used

Answer 12

Planetary gear sets

Question 13

Another name for double helical gears

Answer 13

Herringbone gear

Question 14

What type of thrust do straight and helical gears create

Answer 14

Straight: Radial thrust

Helical: Radial and Axial thrust

Double helical cancel axial thrust

Question 15

3 main components of planetary gear sets

Answer 15

Internal gear (Ring gear)

Planet carrier / planet pinion

Sun gear

Question 16

Another word for gear Face and gear Flank

Answer 16

Face: Top land

Flank: Bottom land

Question 17

Name of Top and Bottom of gear tooth

Answer 17

Top: Tip

Bottom: Root Fillet

Question 18

Which side of a bevel gear is the drive and coast side

Answer 18

Drive: Convex

Driven: Concave

Question 19

What is happening if you can’t get your PTO backlash set correctly

Answer 19

It’s the wrong PTO, Gear tooth pitch is different

Question 20

Gear tooth Clearance purpose

Answer 20

Maintains Lubrication

Question 21

What is Backlash

Answer 21

Ensures there is enough room for gear tooth Expansion and lubrication

Question 22

Non-Hunting gears

Answer 22

Must be timed

Has a specific tooth contact each revolution

Question 23

Partial Non-hunting gears

Answer 23

Every 2 or 3 revolutions before returning to original starting mesh

Question 24

Hunting gears

Answer 24

Each and every tooth will come into contact at some point in operation

Question 25

Explain a Reduction

Answer 25

Small gear Drives a big gear Increased torque, decreased speed E.g: 6:1

Question 26

Calculation for gear teeth ratios

Answer 26

Driven over drive

Question 27

Explain Overdrive gear sets

Answer 27

Big driving a small Increased Speed, decreased Torque E.g: 0.7:1

Question 28

Straight cut gears are also called

Answer 28

Spur gears

Question 29

If a gear tooth has one larger and smaller end, what are they called

Answer 29

Larger: Heel Smaller: Toe

Question 30

Benefits/ disadvantages of a Straight cut gear (Spur Gear)

Answer 30

Inexpensive Thrust bearings not required Can be noisy Often used to drive power takeoffs (PTOs)

Question 31

Where are Internal gears often used

Answer 31

Planetary gear sets

Question 32

3 Members of a planetary gear set

Answer 32

Held gear Drive gear Driven gear

Question 33

Double helical gear Adv/Disadv

Answer 33

Axial thrust loads are offset by one another Very strong Expensive

Question 34

Main purpose of rack and pinion gears

Answer 34

Change Rotary motion to liner

Question 35

Angle drive gears do what

Answer 35

Change the direction of path of power

Question 36

Hypoid Gears are

Answer 36

Common in trucks Below bevel gear centre Strong, more tooth surface in contact Need proper Oil because of heavy loads

Question 37

Amboid Gears are

Answer 37

Above bevel gear centre line Not as common Used in off-road for ground clearance

Question 38

What is a Over hung Pinion shaft

Answer 38

Overhung: 2 bearings

Question 39

What is a Strattle mount pinion shaft

Answer 39

Strattle mount: 3 bearings, stonger

Question 40

What is a worm gear set

Answer 40

Very strong Expensive High torque (winches)

Question 41

In a planetary, what is the held member also referred as

Answer 41

Reactionary member

Question 42

When any 2 members are held in a planetary what is the outcome

Answer 42

Direct drive

Question 43

What is the planetary shaft called that goes into the diff

Answer 43

Quill Shaft