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Millwright2 > Gears, > Flashcards

Gears, Flashcards

1
Q

What are the 4 types of Fixed speed gear box drives

A

Parallel drives
Angle drives
Compound drives
Planetary gear systems

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2
Q

What is Dedendum

A

The part of the tooth that lies between pitch Circle and the route diameter of the gear

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3
Q

What is Backlash

A

The amount to play between meeting teeth it is the difference between tooth space and tooth with measured and thousands of an inch

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4
Q

Some shaft mounted reducers use a device to absorb torsion load shock, what is this device called?

A

Spring type torque arm

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5
Q

What’s a indication of gear wear?

A

Backlash, uneven wear

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6
Q

What is a Internal spur gear

A

Teeth mesh inside larger gear. Rotate same direction quieter than external due to more teeth engaged

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7
Q

Gear materials

A

Ferrous metals,
Non ferrous metals,
Non metallic materials

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8
Q

What are the Two profiles of teeth?

A

Involute or straight

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9
Q

Types of Ferrous metals gears

A

Steel gears- when heated, greatest loads and torque
Cast iron- easy to machine , cheap, good wear resistance and runs quieter but more brittle
Stainless steel- corrosive resistance

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10
Q

What is the Spiral mitre shaft arraignment

A

Intersecting

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11
Q

The Drive gear does what

A

Power in. Is the input gear, caused mating gear to turn

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12
Q

Double helical gears

A

Opposite hand - same shaft. Thrust generated is counteracted by thirst set up

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13
Q

What is a Speed reducer

A

Slower output speed than input . Occurred when small gear drives larger gear. More torque less speed

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14
Q

What is the Hypoid shaft arrangement

A

Crossing

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15
Q

What is Straight bevel , shaft arrangement

A

Intersecting

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16
Q

What is the Herringbone shaft arraignment

A

Parallel

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17
Q

Types of gears?

A 
External/internal spur gears, 
Rack and pinion spur gears,
Helical gears,(single and double)
Herringbone gears,
Straight bevel
Spiral bevel, 
Hypoid, 
Spiral mitre, 
Worm and worm gears
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18
Q

Involute tooth profile have what

A

Slight curve on face of gear teeth.

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19
Q

What do worm gears and worm wheel

A

Connect shafts that cross. Helical teeth around worm called thread. May bore more than one start.

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20
Q

What is worm and wheel shaft arraignment

A

Crossing

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21
Q

Spiral bevel gears have what arraignment

A

Intersecting

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22
Q

What are Bevel gears?

A

Used to connect shafts that intersect usually at right angles.

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23
Q

What are External spur gears?

A

Teeth on the outside of both pinion and gear, connected shafts roster in opposite directions unless a idler is used

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24
Q

What is a Non throated worm gear

A

Teeth have same depth, meshing is only one or two points on teeth

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25
Q

When spur gears are mounted in a gear box, the correct c-c distance is

A

Half the sum of the pitch diameters . Insured proper meshing

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26
Q

What are Hypoid gears

A

Used for transmitting lower between shafts that cross but don’t intersect. Usually a 90° angle.

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27
Q

Planetary gears can be either

A

Spur or helical deign

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28
Q

What is Straight tooth profile gears

A

Have straight faces and flanks. Very noisy. Not suitable for high speed or high power applications unless speeds are low.

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29
Q

Non ferrous metals

A

Bronze- tough and wear resistance, easy to cast and machine

Aluminum- lightweight

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30
Q

Internal gear sets have gears moving how?

A

Both in same direction

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31
Q

What are Straddle mounted gears

A

Mounted between 2 bearings. Stronger and has less deflection under life than overhung

32
Q

What is a Mesh pattern

A

A mesh pattern describes the area of contact between two meeting teeth

33
Q

What are Helical gears

A

Similar to spur gears except gear teeth are at an angle to the bore of the gear. Two or more teeth mesh at same time , smooth and quiet

34
Q

The distance that one thread advances during one revolution is called?

A

Lead

35
Q

What is End play

A

When the gear or shaft is allowed to move axially, for some arrangement end play is required. For others is damages gear train

36
Q

What are the Conditions for gear meshing

A

Diameter pitch
Pressure angle
Tooth profile

37
Q

What does a idler gear do

A

Between drive and driven gear, connect two gears with a center to center distance thaf is greater than the diameter of the gears

38
Q

What is a Mounting distance?

A

Distance from the back of the gear hub to the apex

39
Q

What is the Double helical shaft arrangement

A

Parralel

40
Q

A major hidden danger with high ratio planetary drives is what?

A

Reverse torque lock up.

41
Q

What is a Speed increaser

A

Faster output speed, larger gear drives a smaller gear. Less torque more speed

42
Q

What is Preloading a bearing

A

Giving bearing less than 0 axial clearance

43
Q

What is the Driven gear

A

Power out. Output gear forces to turn

44
Q

What is the External and internal spur shaft arrangement

A

Parralel

45
Q

Do Gears have slippage?

A

False

46
Q

What are Mitre gears

A

1:1 ratio - cone angle of 45°

Change shaft direction without altering drive ratio

47
Q

What are 3types of Shaft arraignment

A

Parallel
Centrelines intersecting at 90°
Centrelines crossing at 90°

48
Q

A Pressure angle has what?

A

14.5% or 20%

Gears with angle of 20% have more stregth and wear resistance because they have fewer teeth on pinions

49
Q

Bevel gears that have there teeth cut Parralel to the axis of their bore called

A

Straight bevel gears

50
Q

Purpose of backlash

A

Allow for tooth expansion(heat)

Allow lube to escape,prevent interference with incoming and outgoing teeth

51
Q

A Throated worm has what

A

Better contact between worm and wheel, single throated outline of worm gear teeth curved match shape of worm

52
Q

Diffence between spur and helical gears?

A

Spur do not have axial thrust but are weaker and nosier at high speeds.
Helical gears are stronger and quieter but have some axial thrust

53
Q

Characteristics of a spur gear

A

Teeth cut parallel to bore, smaller gear is called pinion, do not generate axial thrust p

54
Q

On a gear box the lubricant should be changed when

A

Every 20,000 service hours or after 4gears. In case of extreme conditions a earlier change can be recommended

55
Q

The point in which the cones pivot is called(bevel gears)

A

Apex

56
Q

Straight mitre shaft arraignment

A

Intersecting

57
Q

What is a Direct drive

A

Input and output speed are same speed 1:1

58
Q

What is a Gear train?

A

When two or more gears mesh or work together as a unit

59
Q

What is Rack and pinion shaft arrangement

A

One shaft only

60
Q

What is Addendum

A

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

61
Q

When a odd number of gears mesh?

A

Rotation in same direction

62
Q

What are Herringbone gears

A

Two helical gears abbutted - often used on slow turning heavy loads

63
Q

What is a Over hung gear

A

Has a bearing supper on only one side. Keep close to bearing for more support

64
Q

What are Non metallic gears

A

Quiet at high speeds, natural or synthetic

Plastic, laminated phenolic, carbon fibre.

65
Q

What are examples of light application open gear drives

A

Small conveyers,textile machinery, small er engine lathes

66
Q

3 parts of a planetary gear system

A

1sun gear

  1. Carrier with planted gears mounted to it
  2. Ring gear
67
Q

When a even number of gears mesh the last rotates in?

A

Opposite direction

68
Q

Compound gear train must have

A

Three or more shafts and four or more gears. Good where higher reduction or speed is important

69
Q

When a Parralel shaft is connected by single set of helical gears the shaft develops axial thrust. The direction depends on

A

Whether shaft is a drive or driven, direction of rotation, the hand and gear on the drive shaft.

70
Q

Single helical shaft arrangement

A

Parallel or crossing

71
Q

If two members of plantetary gears are locked up

A

Produces direct drive

72
Q

What are Single helical gears

A

Same helix angle, diamtrel pitch, pressure angle, correct center distance

73
Q

Causes of gear wear?

A

Lack of lube,
Abrasives in gear train,
Incorrect tooth contact
Extended heavy loads

74
Q

What is a Rack and pinion

A

Used to convert rotary motion to a liberal motion and vice versa. Used to open and close chute doors, large air valves etc

75
Q

Can you use layout out blue for checking gear mesh?

A

No

Millwright2 (3 decks)

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