6.9 Transmissions✅(2)

Question 1

What are the benefits of gears used in conjunction with bearings and shafts

Answer 1

• transmit power and increase or decrease rotational speed

Question 2

Which gear is the most popular type for precision cylindrical gears

Answer 2

Spur gears

Question 3

What is the advantage of a spur gear

Answer 3

• easy to manufacture

Question 4

What is the disadvantage of a spur gear

Answer 4

• noisy in operation

Question 5

When 2 spur gears of different sizes mesh together, what is the larger gear called

Answer 5

• wheel (spur)

Question 6

When 2 spur gears of different sizes mesh together, what is the smaller gear called

Answer 6

• Pinion

Question 7

What is a spur gear

Answer 7

• straight teeth parallel to the shaft’s axis and connect parallel shafts only

Question 8

In a spur gear, what is the external teeth used for

Answer 8

• change of speed is required, and the shafts are parallel to each other

Question 9

In a spur gear, what is the internal teeth used for

Answer 9

• when a change of speed is required whilst maintaining a overall minimum diameter

Question 10

Advantage of helical cut (spur gear)

Answer 10

• carry heavier loads at higher speeds
• run more smoothly and quietly

Question 11

Where are bevel gears used between

Answer 11

• intersecting shafts and can be designed for any angle of intersection

Question 12

example of a bevel gear

Answer 12

main drive shaft of an aircraft engine to drive the accessory gearbox

Question 13

Advantages of bevel gears

Answer 13

• quieter and smoother in operation
• carry greater loads

Question 14

Is hypoid gears or spiral bevel gears more quieter and smoother in operation

Answer 14

• hypoid gears

Question 15

• Which gear suffer from heavy sliding contact and require extreme pressure lubricant

Answer 15

hypoid gears

Question 16

Advantages of worm gears

Answer 16

• quiet
• carry heavy loads

Question 17

worm gears are inefficient compared to other gears due to the large sliding movement of their teeth (T or F)

Answer 17

• T

Question 18

What does a worm wheel offer in a worm gear

Answer 18

• offer high reductions in single steps

Question 19

Where would a worm gear be used

Answer 19

• aircraft flap control systems

Question 20

What is a rack and pinion system used to transmit

Answer 20

motion between a rotating spur gear and linear toothed rack

Question 21

What does rack and pinion system convert

Answer 21

rotational motion into linear motion

Question 22

Where would a rack and pinion be often used on

Answer 22

• leading edge flaps for extension and retraction

Question 23

A gear is a toothed wheel that, when operated, transmits motion from one shaft to another (T or F)

Answer 23

T

Question 24

Which gear is the small gear in a mechanical advantage system

Answer 24

drive gear

Question 25

Which gear is the large gear in a mechanical advantage system

Answer 25

driven gear

Question 26

What is the gear ratio formula

Answer 26

number of teeth on driven gear/number of teeth on drive gear

Question 27

How do you calculate speed ratio

Answer 27

input speed/speed ratio

Question 28

What are Idler gears also named as

Answer 28

- Intermediate gears

Question 29

Where would you use a idler gear

Answer 29

- Used between 2 gears

Question 30

Does the presence of an idler gear make a difference to the ratio of speed between input and output

Answer 30

no

Question 31

A reduction gear is an arrangement by which an input speed can be lowered to obtain a slower output speed with the same or equivalent output torque (T or F)

Answer 31

T

Question 32

What is primarily used to reduce gearing in aircraft engines

Answer 32

Epicyclic, or planetary gears

Question 33

What is backlash

Answer 33

clearance between gear teeth at the meshing point

Question 34

What does excessive backlash indicate

Answer 34

worn gearing

Question 35

What is a belt drive used for

Answer 35

- change the speed of rotation

Question 36

What is a belt

Answer 36

- loop of flexible material used to mechanically link or drive 2 or more rotating shafts

Question 37

What is a friction drive belt

Answer 37

- relies on friction between belt and pulley to transmit power - requires correct tension

Question 38

What is a positive drive (synchronous) belts

Answer 38

- relies on teeth engagement on belt with grooves on pulley

Question 39

What are modern day belts made out of

Answer 39

- nylon - aluminium with reinforced, rubberised fabric

Question 40

Flat belts are not advisable for high outputs at high speeds (T or F)

Answer 40

T

Question 41

Advantages of V-belts

Answer 41

- low cost - easy installation - wide range of sizes

Question 42

What is the operational advantage of a V-belt

Answer 42

- wedging action into the pulley groove

Question 43

When were synchronous belts first introduced

Answer 43

1940

Question 44

What are synchronous belts also known as

Answer 44

timing belt

Question 45

What are V belt pulleys solely used for

Answer 45

- transmitting power between 2 parallel axis

Question 46

What are leaf chains

Answer 46

- simple form of steel chains, consisting of link plates and pins - very strong

Question 47

Advantage of chain drives

Answer 47

chain cannot slip on the sprocket because of the teeth

Question 48

Disadvantage of chain drive

Answer 48

- heavy, noisy, more expensive than belt pulley system drive system - Used where slipping must not occur

Question 49

How is a sprocket locked to the shaft

Answer 49

- by the use of a keyway or grub screw

Question 50

Chains are only used where slipping must not occur (T or F)

Answer 50

T

Question 51

What is a sprocket

Answer 51

Toothed wheel that fits onto a shaft

Question 52

Leaf chains must be used for low or high speed applications?

Answer 52

Low speed

Question 53

Leaf chains or chain drive cannot slip?

Answer 53

Chain drive as they have teeth

Question 54

Flat belts are not advisable for high outputs at high speeds (T or F)

Answer 54

T