6.9- Transmissions

Question 1

How is power transmission achieved from engine to flying controls?

Answer 1

Through the use of belts, cables, control chains, chain wheels, pulleys and levers.

Question 2

What other components may you find in transmissions?

Answer 2

Shafts, pull and push rods, cranks, eccentrics, threads, friction wheels, hydraulics and compressed air.

Question 3

What do chains provide?

Answer 3

Strong, flexible and positive connections.

Question 4

Where are chains generally used?

Answer 4

Where it becomes necessary to change the direction of controls runs in systems where considerable is exerted.

Question 5

What 3 systems might chains be used in?

Answer 5

Control columns
Aileron and elevator controls
Trim controls

Question 6

How are chains classed?

Answer 6

Pitch, roller diameter and width between plates.

Question 7

What are some benefits of roller chains?

Answer 7

Low frictional loss

low maintenance.

Question 8

What purpose does a chain cover serve?

Answer 8

Prevents jumping of the chain creating separation between chain and teeth.

Question 9

What type of couplings do you get?

Answer 9

Solid
moveable and disconnectable
safety

Question 10

What are the two best known solid couplings?

Answer 10

Sleeve couplings and disk couplings.

Question 11

Where is a moveable coupling used?

Answer 11

If the shafts are not in alignment or if the position changes during operation?

Question 12

What class of coupling is an elastic coupling?

Answer 12

Moveable.

Question 13

Cross links such as universal joints are used to transfer what and what’s their benefit?

Answer 13

Stronger forces

They require no maintenance.

Question 14

If a drive gear has 50 and the driven gear has 100 teeth what is the ratio, the mechanical advantage and what does that mean?

Answer 14

1:2
MA is 2
Which means the power required to drive the driven gar is halved.

Question 15

What does a toothed wheel gear provide?

Answer 15

Transfer rotational movement at low speed without slip.

Question 16

Where are external spur gears used?

Answer 16

When a change of speed is required and the shafts lie parallel to each other.

Question 17

What are helical gears used for?

Answer 17

Used to transmit drive between parallel shafts.

Question 18

What is an advantage of helical gears?

Answer 18

They have more teeth in mesh to provide a larger contact area.

Question 19

What is rack and pinion?

Answer 19

Linear actuator. The pinion is the circle and the rack the bar.

Question 20

What are bevel gears used for?

Answer 20

Used to transmit drive between shafts with intercepting axis.

Question 21

What’s the benefit of herringbone over helical gears?

Answer 21

The axial forces are eliminated, therefore they are used for large forces.

Question 22

What is a gear ratio?

Answer 22

Direct measure of the ratio of rotational speeds.

Question 23

If the driven gear is smaller than the drive gear will it turn faster or slower?

Answer 23

Faster.

Question 24

How do you work out gear ratio?

Answer 24

Driven gear teeth divided by drive gear teeth.

Question 25

If a gear ratio is 1.5, what does that represent?

Answer 25

That the driven gear must turn 1.5 times before the drive gear has done 1 turn.

Question 26

What is gear backlash?

Answer 26

The clearance between gear teeth at the mesh point. Excessive backlash would be indication of wear.

Question 27

What is an idler gear?

Answer 27

The gear interposed between the driven and drive gear.

Question 28

What is an intermediate gear?

Answer 28

Positioned between the drive and one or more driven gear in a train, it could transmit its own drive.

Question 29

What is the pinion?

Answer 29

The term used to describe the smaller of two mating gears.

Question 30

What is the lay shaft?

Answer 30

The shaft that supports an idler gear or intermediate gear.

Question 31

What is a gear train?

Answer 31

Two or more gear wheels, can be used to alter output directions.

Question 32

What is a compound gear?

Answer 32

A gear with more than one driving face.

Question 33

What is a reduction gear?

Answer 33

An arrangement where the output is slowed but the torque remains the same or higher.

Question 34

What does a planetary (epicyclic) reduction gear train consist of?

Answer 34

Sun (driving) gear driving three or more equi-spaced gears known as planet pinions, and the annulus gear.

Question 35

What is the principle of planetary (epicyclic) reduction gear train?

Answer 35

The input comes through the sun gear which in turn spins the planet pinions within the annulus. The result is the annulus ring spinning the same direction as the sun gear but much slower.

Question 36

What number of stages is rarely used on single pulley drives?

Answer 36

More than 5, because it would take up too much space.

Question 37

What happens if two three stage belts are arranged in series?

Answer 37

There will be 9 rotational speeds not 6.

Question 38

What are the two types of variable gear?

Answer 38

Caster swivel wheel gears and driven key type transmission.

Question 39

What can driven key type gears only be used for?

Answer 39

Transmit small forces at low rotational speeds.

Question 40

What’s the benefit of cable transmission?

Answer 40

They are versatile, offer movement free of play, and weight saving.