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Industrial Mechanic 2nd Block, Harmonized > Alb Mod Gearing Fundamentals > Flashcards

Alb Mod Gearing Fundamentals Flashcards

1
Q

Gears that are exposed to the outside environment are called:

A

Open gear drives

Note: used on light duty applications, or where sealing the gears is impractical or impossible

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2
Q

With an open gear drive system, gear wear is:

A

more excessive

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3
Q

Gear drives contained within a gearbox with a lubrication supply are:

A

Enclosed gear drives

Note: Have a long working life

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4
Q

____ are matched pairs of gears, manufactured together intended to mate with each other.

A

Gear sets

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5
Q

When two or more gears mesh or work together, they are called a:

A

Gear train

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6
Q

Between a pair of gears, the smaller gear with fewer teeth is referred to as:

A

pinion

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7
Q

With bevel and hypoid gear sets, the smaller gear is called the pinion and the larger gear is called the:

A

Crown or Ring gear

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8
Q

____ is when the input speed of the gearbox is the same as the output speed

A

direct drive

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9
Q

A gear train with a slower output speed than input speed is called a

A

Speed reducer

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10
Q

a gear train with a faster output speed than input speed is called a

A

Speed increaser

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11
Q

When a speed reduction occurs, it results in a mechanical advantage, which is an increase in

A

torque

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12
Q

A ____ has a bearing support on only one side

A

overhung gear or load

Note: Also known as cantalever

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13
Q

The general practice with overhung gears is to keep:

A

overhung gears very close to the bearing support

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14
Q

______ gears are mounted between two bearings

A

straddle mounted

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15
Q

____ gears have teeth on the inside diameter of the gear

A

Internal

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16
Q

____ gear trains have three or more shaft and four or more gears

A

Compound

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17
Q

The final ratio of a compound gear train is equal to all the ratios:

A

multiplied

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18
Q

___ is when the gear or shaft is allowed to move axially

A

end play

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19
Q

____ a bearing in a gearbox id done by giving a bearing less than zero axial clearance

A

Preloading

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20
Q

Gear wear can be caused by: (4)

A
  • Lack of lubrication
  • Abrasives
  • Incorrect tooth contact
  • Heavy loads
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21
Q

A ____ exists when one gear or shaft is allowed to move axially to its best position

A

floating gear or shaft

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22
Q

Gears that have a helix angle can be either:

A

Right or left handed

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23
Q

In worm and worm wheel gearboxes, the worm is:

A

smaller gear that looks like a screw thread

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24
Q

The ___ is the side in contact with the other gear teeth while torque is applied. The other side is called the coast side

A

drive side

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25
Q

The ____ is the radial distance from the pitch circle to the top land of the tooth

A

addendum

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26
Q

the ____ is the radial distance from the pitch circle to the bottom land of the tooth.

A

dedendum

addendum + clearance

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27
Q

The ___ is the total height of the whole tooth, addendum + dedendum

A

Whole depth

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28
Q

___ is the depth that the gear tooth extends toward the root of the mating tooth while in full mesh

A

Working depth

29
Q

___ is the space between the bottom land of one tooth and the top land of the meshing gear

A

Clearance

30
Q

The ____ is the maximum diameter at the top land of the gear teeth

A

Outside gear diameter

31
Q

____ is the distance from the center of one tooth to the center of the next tooth at the pitch circle

A

Circular pitch or gear pitch

32
Q

The pitch circle is located, approximately:

A

in the middle of the gear teeth

33
Q

The ____ of a tooth is the contact part of the tooth on the addendum

A

Face

34
Q

____ is the contact part of the tooth below the pitch circle including fillet

A

tooth flank

35
Q

____ is the distance from one side of the tooth to the opposite side

A

face width

36
Q

____ is the distance of the gear tooth at the pitch circle

A

chordal thickness

Indicates tooth strength

37
Q

Crowning a gear tooth is cutting a slight curve on the face of the tooth from side to side. The purpose is to:

A

Prevent highly concentrated loads on the ends or edges of the gear teeth that could cause the teeth to fracture

38
Q

The ____ is the angle between the line of action and a line tangent to the pitch circles

A

Pressure angle

39
Q

The angle of a tooth from the shaft axis is the:

A

helix angle

40
Q

Helix angles can be right or left handed. They lead to smoother tooth action, but have: (2)

A
  • More sliding friction

- Greater axial thrust

41
Q

A ___ is the term that describes the number of thread starts on a worm

A

start

42
Q

The more starts a worm has, the ____ the worm wheel advances per turn

A

Faster

43
Q

The face of the tooth on many gears has a radius across the flank and the face of the tooth. This is referred to as an:

A

Involute profile.

Note: Makes meshing of gears quieter and smoother

44
Q

___ is the clearance between gears at the pitch line. Half is cut into each gear.

A

Backlash

45
Q

____ is the ratio between the number of teeth on a gear and the pitch diameter. Indicates tooth size.

A

Diametral pitch

46
Q

When reading diametral pitch, the smaller the number, the ___ the tooth size

A

larger

47
Q

lack of blacklash, incorrect center distance, gear center out of tolerance, bent shafts and thermal expansion can all cause:

A

Binding

48
Q

The ____ is the angle of the gear tooth

A

pressure angle

49
Q

The two most common pressure angles are 14.5° and 20°. Which one is stronger?

A

20°. Tooth is wider at the base

50
Q

If a gear set has:

  • Same diametral pitch
  • same pressure angle
  • correct hand of gear
  • shafts in correct position
  • same helix angle

The gears will have proper:

A

Mesh

51
Q

Gear teeth can have one of two profiles:

A

Involute or straight

52
Q

An involute profile has a ____ on the face of the gear teeth

A

slight curve

53
Q

Straight cut teeth are:

A

Very noisy

Note: Also not suitable for high speed or high power applications

54
Q

When an even number of gears are in mesh, the last gear rotates ___ the drive gear

A

opposite

55
Q

An __________ has both gears moving in the same direction

A

Internal gear set

56
Q

____ gears are between the drive and driven gear. they have no effect on the gear ratio, but can change the rotation, and connect gears with a greater center to center distance.

A

Idler gears

57
Q

If a gearbox is a speed increaser, ratios are numberically:

A

Less than one.

0.50:1, often called overdrives

58
Q

When measuring the torque on a gear, the effective lever length is equal to the:

A

Radius of the gear

59
Q

What are the three basic positions used to properly mesh gears? (3)

A
  • Parallel
  • Intersecting
  • Crossing over at 90°
60
Q

These gears were one of the first developed. Teeth are cut parallel to the shaft axis. Only suitable for shafts that are parallel. No axial thrust, unless misaligned. Easy to manufacture. Sliding and rolling action, but the power transfer happens over a rolling action.

A

Spur gear,

Note: Can be used in 3 arrangements, internal, external and rack and pinion.

61
Q

These gears have their teeth cut at an angle to the shafts axis. They are stronger and have more teeth in contact than a spur gear. Can be used in a single or double setup, to help eliminate thrust loads. When used in parallel, opposite hand helix angles are used. When crossing over at 90, same hands are used.

A

Helical gears

Most common helix angles are 7 to 23°. Greater the angle, more teeth are in contact, more thrust

62
Q

These gears are similar to double cut helical gears, except the teeth form a point in the center of the gear. Cancels out thrust loads. High speed heavy load applications.

A

Herringbone gears

63
Q

These gears are used on shafts that have intersecting axis. Most commonly cut at a 90° angle, but can intersect at other angles. Develop both axial and radial loads. Can be straddle mounted or overhung. Teeth can be straight or curved.

A

Bevel gears.

64
Q

These are bevel gears, but have a 1:1 ratio.

A

Mitre gear

65
Q

This is the simplest bevel gear, teeth are straight but tapered to compensate for the smaller inside tooth diameter. Noisy and rough, do not have a high torque capacity

A

Straight bevel gears

66
Q

These bevel gears have curved teeth that are angular to the shaft axis. Stronger, have a smoother transfer of power, more teeth in contact. Manufactured in pairs. Gears must be in opposite hand. Generate a thrust load

A

Spiral bevel gears

67
Q

These bevel gears have teeth cut similar to straight bevel gears, but the teeth are curved. Teeth do not cut at an angle. Are smoother and quieter than straight cut. Does not generate a thrust load.

A

Zerol bevel gears

68
Q

When gears are too close together, clearance is insufficient, gears are noisy and will bind and wear. If there is excessive clearance:

A

Cannot transfer rated load, may be noisy

Industrial Mechanic 2nd Block, Harmonized (28 decks)

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