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Millwright 2nd Year > Gears > Flashcards

Flashcards in Gears Deck (54):
0

Open gear drives are exposed to what and are suitable for what kind of application

Outside environment and are suitable for light duty applications

1

Enclosed your drives are contained how

Contained in a gearbox with lubrication supply

2

What are gear sets used for

To be meshed together in pairs and intended to mate

3

What is gear train

Two or more gears that mesh or mate together

4

What is a pinion

Two gears with different number of teeth
gear with fewer amount of teeth is the pinion

5

If the smaller gear is the pinion what is the larger gear in a bevel and hypoid mating gear

Crown gear

6

What is the drive gear

The gear the drives the output gear

7

What is the driven gear

Gear that is driven by the drive gear

8

What Kinda drive has the same speed as the input and output

Direct drive

9

What does a speed reducer do

If you have a fast input speed the output speed will be reduced
Ex
Input will have a small gear going into a big gear on the output

10

Speed increaser
Is the drive gear smaller or bigger

Bigger

11

What is an overhung gear

Bearing support only on one side of the gear

12

What is a straddle mounted gear

A bearing on both sides of the gear

13

Internal gears have teeth on the inside or outside of the gear plank and are they smoother or not as smooth

Inside
Smoother

14

Compound gear train has how many shafts and how many gears

Three or more shafts and four or more gears

15

Define end play

The gear or shaft can move axially

16

Pre-loads have how much axial clearance for proper gear mesh

Zero

17

What is the axis of rotation

Centerline around which gear or parts revolve

18

What causes gear wear

Lack of lubrication, abrasives and bad tooth contact

19

What is a floating gear or shaft

Where one gear or shaft is allowed to move axially to its best position kind of like bearing

20

Right and left-hand gears are called what kind of angle

Helix angle

21

How can you tell if you have a left or right hand gear

Which ever way the gear points away from centerline of the shaft

22

Describe a worm and worm wheel gear set

The worm is the smaller gear and looks like a screw the worm wheel is a larger circular gear

23

The clearance between gear teeth and the pitch line is called what

Back lash

24

Top half of the gear tooth is called what

Addendum

25

Bottom half of the gear tooth including the clearance is called what

Dedendum

26

Total depth of the tooth top to bottom including the clearance is called what

Whole Depth

27

Working depth includes what minus the clearance

Addendum + Dedendum

28

What are the two best pressure angles in degrees

20° and 14°

29

If you have a steep and smooth helix angle is this better or worse

Better

30

If you have more starts then less starts on a worm gear box will the worm wheel move faster or slower each revolution

Faster
example 3 starts equals three pitches each revolution

31

What is the formula to get diametral pitch

Number of teeth on your gear divided by pitch diameter

32

List three ways to have proper gear mesh

Have the same diametral pitch
same pressure angle
and correct your hand left or right
Same helix angle

33

Can idlers change the speed of the input and output gear

No because idlers only change the direction or keep it the same

34

What Kind of gears are suitable for shafts parallel to each other with no axial thrust unless misaligned (cowboy)

Spur gears

35

Where will external spur teeth be on a gear plank

On the outside

36

Where will the internal spur teeth be on a gear plank

On the inside

37

What kind of gear system is on a arbor press

Rack and pinion

38

How are single helical gears cut

They have the teeth cut at an angle to the shaft of the axis

39

Are helical gears stronger or not stronger then spur gears

Stronger because they have more teeth in contact at one time

40

Can helical gears be used on shafts that cross over 90° or other angles

Yes but the gears have to be left-hand and right-hand in order to mesh proper

41

What are the most common angles for helical gears

7° to 23°
most industrial gears have a 20° pressure angle

42

What kind of loads and speed applications are herringbone gears used for

High speeds and heavy loads

43

What kind of gear is similar to a doublecut helical gear

The herringbone gears

44

For bevel gears what is the most common intersection angle

90°
but some intersect at other angles

45

Give four types of bevel gears

Miter
straight
spiral
and zerol

46

On gears where the shafts must intersect at 90° are called what kind of bevel gear

Mitre gear

47

Worm bleed refers to the distance by which what

One tooth on the worm advances in one turn this is determined by the number of starts on the worm

48

Parallel
angle
compound
and planetary gear systems are all what kind of drives

Fixed speed gearbox drives

49

What kind of specific combination of gears can produce several speed and torque combinations from one set of gears in a small space
Ex: Sun gear, carrier with planet gears mounted to it and a ring gear

Planetary gear systems

50

What kind of methods do you use to check for acceptable mesh patterns while being reassembled

Prussian blue
Venetian red
Black light
pencil lead

51

What is a good practice before using Prussian blue on your gear teeth to measure mesh patterns

Clean both gears very thoroughly

52

What is the best tool to use to measure backlash

Dial indicator

53

Tie rod torque arms should be mounted in a position that forms what kind of angle

A 90° angle