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Millwrong > Belts > Flashcards

Belts Flashcards

1
Q

____________ have a wedge shaped cross section.

A

V-belts

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2
Q

How do V-belts transmit power?

A

by gripping the sides of a groove in a pulley

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3
Q

What is the most cost effective means of power transmission:

A) V-belts
B) Gears
C) Chains

A

A) V-belts

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4
Q

True or false:

While V-belts are considered the most cost effective means of power transmission, they are also considered to be unreliable.

A

false;

they are considered highly reliable

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5
Q

True or false:

V-belts are able to absorb shock.

A

true

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6
Q

True or false:

The construction of V-belts allows for the belt to slip on overload.

A

true

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7
Q

Do V-belts require lubrication?

A

no;

  • lubrication actually degrades the V-belts gripping ability
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8
Q

V-belts have a minimum of ______º arc of contact.

A

120º

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9
Q

Are V-belts suitable for positive drive engagements?

A

no;

they slip on overload, so they’re not good for positive drive applications

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10
Q

Can V-belts be used in areas of high ambient temperature?

A

no;

they degrade when exposed to high temperatures

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11
Q

True or false:

V-belts are not practical for high surface speeds because of problems with dynamic balancing.

A

true

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12
Q

What part of a V-belt construction consists of cords that carry the load?

A

the tensile members

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13
Q

What is the pitch line of a V-belt?

A

the pitch line is where the tensile members of the belt are located

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14
Q

With a V-belt, the _______________ material transmits the power between the sheave and the tensile member and supports the cords.

A

compression

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15
Q

True or false:

The compression material of a V-belt is often fibre-filled to provide transverse rigidity.

A

true

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16
Q

On a V-belt construction, what purpose does the cover serve?

A

it protects the internal parts from wear and the environment

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17
Q

How does a V-belt transmit power?

A

through friction between the sides of the belt and the sleeve transmitted to the tensile members of the V-belt

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18
Q

The amount of power a V-belt can transmit depends on what 2 things?

A
  1. strength of the tensile members
  2. grip of the belt on the pulley
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19
Q

What 3 things effect the grip of a V-belt on a pulley?

A
  1. arc of contact
  2. tension applied to the belt
  3. coefficient of friction between the belt and pulley
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20
Q

As it concerns belts, what is creep?

A

a change in belt speed from the tight side to the slack side

  • the loss of driving speed due to the lengthening and shortening of the belt as it cycles from the tight side to the slack side
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21
Q

What effect does an increase in load have on creep?

A

the arc around the pulley through which creep occurs increases with load

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22
Q

What is the result of creep (not excessive)?

A

a slight belt flap on the return side

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23
Q

True or false:

The flutter or flapping of a belt is normal.

A

true

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24
Q

What happens when the load and tension on a V-belt are increased to the point where the arc of creep extends all the way round the pulley?

A

the belt will slip

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25
Q

What 4 negative effects does creep have on a V-belt arrangement?

A
  1. loss of power between driver and driven pulleys
  2. increased wear on belt and sheaves
  3. additional heat (belt degradation)
  4. excessive vibration
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26
Q

True or false:

The gripping action of a V-belt is entirely on the sides of the belt and the sides of the sheave groove in which it is wedged.

A

true

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27
Q

True or false:

A V-belt can touch the bottom of the sheave groove.

A

false;

  • if the V-belt touches the bottom of the sheave the sheave is excessively worn
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28
Q

What is the most widely used series of V-belt?

A

the classical or standard series

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29
Q

What are the designations of classical or standard V-belts?

A

A, B, C, D, and E

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30
Q

What is another name for multiple series V-belts?

A

classical or standard series

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31
Q

What type of V-belt has the highest tolerance for poor operating conditions?

A

classical or standard series

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32
Q

What type of V-belt would be selected for an application where maintenance is infrequent?

A

classical or standard series

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33
Q

True or false:

The classical series V-belt has the most reliability for unusual drives (reverse bend, clutching, and quarter turn).

A

true

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34
Q

True or false:

An advantage of a classical series V-belt is that the cover wraps completely around the belt to provide protection on all sides of the belt.

A

true

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35
Q

What 4 types of V-belt were developed from the classical series V-belt?

A
  1. cogged raw edge
  2. banded (joined classical belts)
  3. double V
  4. fractional HP
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36
Q

What belt code designation identifies a cogged raw edge V-belt?

A

X = cogged raw edge

  • AX, BX, CX, etc.
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37
Q

True or false:

The cogs on cogged raw edged belts allow for greater flexibility and enhanced airflow, resulting in a cooler operation when compared to a standard series V-belt.

A

true

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38
Q

What effect do the cogs on cogged raw edged belts have on the belt bend radius?

A

the cogs allow the belt to make tighter bends

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39
Q

Which V-belt would have a smaller bend radius: a cogged raw edged belt or a classical series?

A

cogged raw edge;

  • the cogs allow for a tighter bend radius
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40
Q

Which V-belt fits the sheaves more accurately: a cogged raw edged belt or a classical series?

A

cogged raw edge

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41
Q
  1. Which V-belt is more efficient in terms of power transmission, weight, and space: a cogged raw edged belt or a standard belt?
  2. Why is this?
A
  1. cogged raw edge
  2. the higher coefficient of friction results in a smaller belt vs. a standard series
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42
Q

Can a cogged raw edged V-belt be used on clutching drives, drives that are subject to shock loads or drive with changing centre distances?

A

no

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43
Q

True or false:

A cogged raw edged V-belt cannot be subjected to reverse bending.

A

true

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44
Q

True or false:

A cogged raw edged V-belt can be used in applications where some slip is required.

A

false;

they cannot be subject to slip

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45
Q

What is the cause of the limitations of cogged raw edged V-belts?

A

the aggressive mature of the grip of the belt

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46
Q

What are banded V-belts?

A

belts constructed by jointed two or more standard belts with a common backing

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47
Q

What other names are banded belts known under?

A

Power-band and joined classical belts

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48
Q

What 3 problems were joined classical belts developed to solve?

A
  1. belt vibration
  2. belt whip
  3. belt turnover
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49
Q

Why is sheave alignment critical with banded belts?

A

banded belts have less ability to flex sideways than individual belts

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50
Q

True or false:

Banded belts have more power transmission ability when compared to the same number of individual belts.

A

false;

they have the same power transmission as the same number of individual belts

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51
Q

True or false:

Banded belts require more maintenance than individual V-belts.

A

true

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52
Q

What are the designations of banded belts?

A

B, C, D

  • same as the classical seres belts
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53
Q

What types of belts would be designated AA, BB, and CC?

A

double V-belt

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54
Q

What is a hexagonal belt?

A

a double V-belt

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55
Q

This type of belt is a double-sided standard series V-belt.

A

a double V-belt

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56
Q

True or false:

Double V-belts are capable of transmitting power on both sides in serpentine drives

A

true

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57
Q

What type of V-belt is designated 2L, 3L, 4L, or 5L?

A

fractional HP V-belts

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58
Q

True or false:

Fractional HP V-belts are generally used for drives of less than 1 HP, but some OEM’s offer them up to 17 HP.

A

true

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59
Q

True or false:

Fractional HP belts can go very fast.

A

true

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60
Q

When a new standard series V-belt is installed on a sheave, how far down in the sheave groove should the top of the belt sit?

A

The top of the belt should be proud to the top of the sheave

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61
Q

What types of V-belts are designated 3V, 5V, and 8V?

A

high capacity V-belts

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62
Q

What are narrow V-belts?

A

the same as high capacity V-belts

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63
Q

What designations are used for high capacity V-belts?

A

3V, 5V, and 8V

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64
Q

What designations would be used with hexagonal belts?

A

AA, BB, and CC

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65
Q

What designations would be used for a fractional HP V-belt?

A

2L, 3L, 4L, and 5L

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66
Q

What design characteristic of a narrow V-belt increases its capacity?

A

the narrow wedge design provides more support for the tensile members

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67
Q

What are the 2 main advantages of high capacity V-belts when compared to classical series belts?

A
  1. compact
  2. higher power capacity
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68
Q

True or false:

High capacity V-belts are under tensioned if they are tensioned according to the same feel as classical V-belts.

A

true

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69
Q

What are the 2 main limitations of narrow V-belts?

A
  1. require higher tension = higher loading on bearings
  2. increased sheave wear in dusty and abrasive environments (due to higher side wall loading)
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70
Q

True or false:

Alignment and cleanliness are not important for high capacity belt drives.

A

false;

they are important

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71
Q

What is the top width of a 3V high capacity belt?

A

3V = 3/8”

  • 1/8” x 3
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72
Q

What is the top width of a 5V high capacity belt?

A

5V = 5/8”

  • 1/8” x 5
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73
Q

What is the top width of a 8V high capacity belt?

A

8V = 1”

  • 1/8” x 8
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74
Q

True or false:

Worn sheaves affect the performance of joined high capacity belts more than classical banded belts.

A

true

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75
Q

What are the designations of poly V-belts?

A

J, K, L, and M

  • also H for small sheaves and miniature drives
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76
Q

What are V-ribbed belts?

A

the same as poly V-belts

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77
Q

This type of flat belts are thin and have a ribbed driving face that runs in a grooved pulley with a well supported tensile member.

A

Poly V-belt

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78
Q

With a poly V-belt, are the tensile members outside the pulley grooves, or inside of them?

A

outside

  • the tensile members are on top of the pulley vs narrow V-belt which would be in the pulley groove
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79
Q

True or false:

Poly V-belts do not perform well on small diameter pulleys.

A

false;

they perform well on small diameter pulleys

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80
Q

True or false:

V-ribbed belts are ideal for high speed ratios where there is a large difference between the driver and driven pulley diameters.

A

true

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81
Q

True or false:

Poly V-belts can be used with reverse bends or serpentine drives.

A

true

  • found most often on automobiles as the timing belt
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82
Q

Why are poly V-belts ideal for high speed applications?

A

because their light weight and thin cross section

  • heavier = more mass moving around = slower speeds
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83
Q

True or false:

Poly V-belts have a longer belt and sheave life due to equalized loading.

A

true

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84
Q

What are the 2 main limitations of poly V-belts?

A
  1. require special sheaves and high tension
  2. alignment is more critical
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85
Q

What 3 pieces of information do Poly V-belt codes contain?

A
  1. length
  2. section
  3. number of ribs

180J6 = 180” x J size x 6 ribs

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86
Q

What types of belts are used where speed changes are needed?

A

variable speed belts

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87
Q

This types of belt runs in sheaves with specially designed sides.

A

variable speed belt

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88
Q

What are the sides of variable speed sheaves called?

A

flanges

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89
Q

The sheaves used on variable speed drives move axially, so when the axial space is at its smallest, the driven pulley turns the ____________ (quickest/slowest).

A

slowest

  • this is the smallest space between the flanges, not the smallest diameter
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90
Q

When the flanges of a variable speed belt sheave move apart, the belt moves down to a smaller diameter towards the centre. What effect would this have on speed?

A

sheave ∅ ↓ = speed ↑

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91
Q

When the flanges of a variable speed belt sheave move together, the belt moves outward to a larger diameter. What effect would this have on speed?

A

sheave ∅ ↑ = speed ↓

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92
Q

What do the first 2 digits of a variable speed belt designation represent?

A

the top width, in 1/16”

12 = 12 x 1/16” = 12/16” = 3/4”

12 would be a 3/4” wide belt

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93
Q

What do the 3rd and 4th digits of a variable speed belt designation represent?

A

the groove angle

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94
Q

What do the last 3 digits of variable speed belt designation represent?

A

the pitch length of the belt

255 = 25.5”

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95
Q

What is the main advantage of a variable speed belt drive systems?

A

economical way of providing infinitely variable speed

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96
Q

What are the 2 main limitations of variable speed belt drive systems?

A
  1. require special sheaves
  2. not practical for very large HP
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97
Q
  1. What precaution must be taken when adjusting the speed of a variable speed belt drive system?
  2. What can happen if this precaution is not observed?
A
  1. the belts must be turning before adjusting the speed
  2. the adjustment mechanism could be broken
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98
Q

What are two types of belts that can be cut to any length and fastened together?

A
  1. open ended belts
  2. link belts
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99
Q

What designations are used for open ended belts?

A

same cross section letter as standard belts (A, B, C, D, or E), but with VO after the letter.

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100
Q

What designation indicates an open ended belt?

A

VO

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101
Q

What is the main limitation of an open ended belt?

A

it can only carry 1/3 of the load that a corresponding endless belt could carry

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102
Q

What are the 2 main advantages of a link belt?

A
  1. can be used as an emergency replacement for endless belts
  2. available with the same power rating as classical V-belts of the same cross section
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103
Q

What are the 3 main limitations of link belts?

A
  1. more vibration
  2. cannot be used with back idlers
  3. cannot be used with endless belts
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104
Q

What do the two numbers in a round belt designation indicate?

A

1st # = diameter, in 1/16” of an inch
2nd # = length

  • 5 x 33 ⟶ 5 x 1/16” = 5/16” ∅ x 33” length
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105
Q

Identify the length and diameter of a round belt labelled 4 x 365.

A

4 ⟶ belt ∅ ⟶ 4 x 1/16” = 4/16” = 1/4” ∅
365 ⟶ length ⟶ 36.5”

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106
Q

True or false:

Round belts are suitable for quarter turn drives.

A

true

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107
Q

True or false:

Round belts are not suitable for serpentine drives.

A

false

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108
Q

True or false:

Round belts can be supplied as open-ended to allow for custom lengths to be cut and spliced.

A

true

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109
Q

What is the main limitation of a round belt?

A

light duty, fractional HP only

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110
Q

True or false:

The codes on most belts in North America are standardized by the Rubber Manufacturers Association (RMA).

A

true

111
Q

What does the letter designate on an RMA belt designation code?

A

the shape and size of the cross section

112
Q

What do the numbers that follow the letter designation on an RMA belt designation code stand for?

A

the length of the belt in inches

  • the last digit of the length number is a decimal of an inch (255 = 25.5”)
113
Q

What 2 issues do dirt and deposits cause on belts and sheaves?

A
  1. Wear - degradation through abrasion and corrosion
  2. Vibration - imbalance which causes vibration
114
Q

What are the two main reasons to inspect sheaves during cleanup?

A
  1. to check for possible cracks, especially around the hub
  2. check for dynamic balance
115
Q

True or false:

X on belts indicates a cogged raw edge on both imperial and metric belts.

A

true

116
Q

Where is belt length measured?

A

at the pitch line

117
Q

What are the 2 ways to perform a wear check on belts and sheaves?

A
  1. sheave groove gauge
  2. check wear with a new belt
118
Q

What causes a belt to swell?

A

excessive exposure to oil or grease

119
Q

What effect does belt swell have on a belt?

A

the belt becomes soft, and the bottom envelope seam will “open up”

120
Q

What do cut bottom and sidewalls indicate on a V-belt?

A

that the belt was pried overs the sheave during installation

121
Q

What 2 things does fitting a belt involve?

A
  1. aligning the sheaves
  2. tensioning the belts
122
Q

True or false:

Aligning the sheaves reduces vibration and extends belt life.

A

true

123
Q

What is the maximum allowable misalignment of a V-belt?

A

1/16” offset per foot

124
Q

With a belt and sheave arrangement, any runout that exceeds ________” should be corrected.

A

0.005”

  • very difficult to achieve
125
Q

What can happen when using tapered adapter bushings to mount sheaves and the bolts are not evenly tightened?

A

excessive runout

126
Q

True or false:

Belts must be tight enough not to slip under normal operating conditions, but they must not be so tight as to create unnecessary load on the bearings during normal operation.

A

true

127
Q

What causes evenly spaced deep bottom cracks on a belt?

A

a substandard backside idler

128
Q

How is deflection for belt tensioning checked on banded belts?

A

with a special deflection gauge that contacts the entire width of the belt

129
Q

Why is the elongation method usually used to check the tension of banded belts?

A

the high forces required to check with the specialized deflection gauge

130
Q

What is the elongation method for checking belt tension with banded belts?

A

uses an elongation table with a number (length multiplier) that indicates how long the belt should be under proper tension

131
Q

Where can idler pulleys be located on belts?

A

either inside or outside the belt strands

132
Q

Idlers are often added to belt systems for what 3 reasons?

A
  1. increase belt tension
  2. increase arc of contact
  3. prevent belt whip
133
Q

Should idlers be used on reversing drives?

A

no

134
Q

When an outside idler is used to tension a belt, what type of pulley should be used for the idler?

A

a flat pulley at least 1.5 times the ∅ of the smaller pulley

135
Q

When using an outside pulley to increase the arc of contact on a belt system, how should it be positioned?

A

as close as possible to the smaller sheave

136
Q

After increasing the arc of contact, what is another reason to located an idler pulley as close as possible to the smaller sheave of a belt system?

A

to aid with tracking of the belt

  • smaller ∅ = drive sheave, and the belt will wander on the flat side of the idler pulley; having it far away from the large one reduces the angle of misalignment
137
Q
  1. On which span should idler pulleys be located?
  2. Why is this?
A
  1. the slack span
  2. it takes much less force to tension the slack span than drive span
138
Q

Because an outside idler puts a backward bend on the belt, it leads to premature ____________ of the belt.

A

cracking

139
Q

What effect does an inside idler have on the arc of contact of a belt?

A

it reduces it

140
Q

True or false:

Even though an inside idler reduces the arc of contact of belts, if an adequate arc of contact is maintained, an inside idler is more reliable than an outside idler.

A

true

  • no premature cracking due to bending the belt backwards
141
Q

Why is a grooved pulley used on inside idlers?

A

better tracking

142
Q

Where should an inside grooved idler be located?

A

on the slack side, at a point in the span that produces equal arcs of contact on the sheaves

143
Q

Where should an inside flat idler be located?

A

away from the sheave the belt it is travelling towards to prevent unequal arcs of contact

144
Q

What are contact idlers used for?

A

to counteract belt whip produced by long spans or shock loads

145
Q

What is belt whip?

A

belt vibration in the vertical span

  • this is where the belt is vibrating up and down
146
Q

What are contact idlers also known as?

A

kiss idlers

147
Q

How should outside kiss idlers be mounted in a pulley system?

A

located 1/3 of the span distance from the large pulley on the slack span

148
Q

Should a kiss idler be set so that it creates a back bend in the belt?

A

no;

it should just “kiss” the top of the belt

149
Q

What does an automatic take-up on a belt system consist of?

A

a spring on a movable mount or on an idler

150
Q

What function does an automatic take-up perform in a belt system?

A

it maintains belt tension

151
Q
  1. What effect does an automatic take-up have on a belt?
  2. How is the above achieved?
A
  1. it increases the life of the belt
  2. by providing uniform tension throughout the life of the belt (compensates for stretch)
152
Q

True or false:

When tensioning belts, you have achieved the approximate tension when the belt springs back after being bump at mid-span.

A

true

153
Q

If when bumped at mid-span and the belt does not spring back, its tension is too ___________ (tight/loose).

A

loose

154
Q

If when bumped at mid-span and the belt feels like a solid board, it is too ____________ (tight/loose).

A

tight

155
Q

Why is it a good idea to rotate the sheaves of a belts before checking the tension of said belt?

A

to ensure that belt is properly seating the sheave grooves

156
Q

When installing belts, can new belts and old belts be used together on the same sheaves?

A

no

157
Q

How long after initial installation should belt tension be rechecked?

A

during the first 24 to 48 hours

158
Q

With belts, what is a quarter turn drive?

A

when power is transmitted from a horizontal shaft to a vertical shaft

159
Q

What is the maximum speed ratio of a quarter turn belt drive?

A

2.5:1

160
Q
  1. When using a quarter turn drive belt arrangement, the centre distance must be at least:
  2. Why is this distance required?
A
  1. 5.5 times the sum of the large sheave ∅ plus its face width (thickness)
  2. to ensure that the angle at which the belt enters the sheave is not too great
161
Q

When using a quarter turn belt drive, where must the centreline of the horizontal shaft be located in relation to the vertical sheave?

A

it must be above the centreline of the vertical sheave

162
Q

When using a quarter turn belt arrangement, the HP rating of the belt should be derated to ______%.

A

90%

163
Q

What is the greatest concern when running a quarter turn belt drive arrangement?

A

ensure the angle at which the belt enters the sheave groove on the tight side is kept to a minimum

  • this prevents the belts from flipping over the edges of the sheaves
164
Q

With a belt system, start up checks should be repeated after how long after the initial start up?

A

24 to 48 hours

165
Q

With a belt system, squealing sounds or the smell of burning rubber indicate:

A

a loose belt

166
Q

With a belt system, flapping belts on the tight strand indicate:

A

misalignment

167
Q

With a belt system, bearings running hotter than they did before the belt change indicate:

A

too much tension on the belts

168
Q

With a belt system, increased amperage draw on an electric drive after the belt change indicates:

A

too much tension on the belts

169
Q

With a belt system, excessive vibration can be caused by:

A

misalignment or runout

170
Q

What should be used to clean a running belt?

A

brushes

  • avoid entanglement
171
Q

When tensioning a belt to compensate for stretch, how much tension should be added to the belt?

A

just enough to stop the slip

172
Q

What could be the cause of slip if tensioning the belts do not eliminate it?

A

the belts and/or the sheaves grooves are worn

173
Q

True or false:

Belt dressing should be used only as a last resort to avoid a machine outage at a critical time.

A

true

174
Q

With a belt system, what is the cause of chirps?

A

dirt or dust in the sheave grooves or on the side of the belts

175
Q

With V-belts, what is ride-out?

A

how high up on the sheave the belt rides

  • as the sheave wears, the ride-out will decrease
176
Q

What does squealing in a belt at start up or near maximum load indicate?

A

insufficient tension

177
Q

If properly tensioned, what can a squealing belt indicate?

A

overload

178
Q

What does belt whip on the tight span indicate on a belt drive system?

A

insufficient tension

179
Q

What can be a cause of belts snaking?

A

runout or wobble on the sheaves

180
Q

What is the maximum ambient temperature that normal belts should operate at?

A

60℃

181
Q

If stored according to RMA recommendations, how long should belts last on the shelf?

A

8 years

182
Q

What 4 things must be observed when storing belts according to RMA’s recommendations?

A
  1. protect from moisture and high temps
  2. store in original packaging and out of direct sunlight
  3. do not bend or hang on a diameter less than the smallest recommend pulley
  4. relax the tension on belts left on equipment that is to be idle for long periods of time
183
Q

What type of belt would be used where there can be no slip?

A

synchronous belts

184
Q

Positive drive belts and timing belts are names for:

A

synchronous belts

185
Q

This type of belt must be run in special pulleys called sprockets.

A

synchronous belts

186
Q

This type of belt is a flat belt with moulded teeth that engage with a special pulley called a sprocket.

A

a synchronous belt

187
Q

Synchronous belts last about _____ times longer than chain drives.

A

3 times

  • minimum, may last longer
188
Q
  1. Which type of belt requires more tension: a classical V-belt or a synchronous drive?
  2. Why is this?
A
  1. synchronous drive
  2. rely on mechanical engagement vs. coefficient of friction
189
Q

Do synchronous belts require re-tensioning after start up?

A

no;

  • they need never be re-tensioned
190
Q

Do synchronous belts require lubrication?

A

no

191
Q

Synchronous belts are ______% efficient.

A

98%

192
Q

True or false:

Synchronous belts are compact, have a wide speed range (up to 30,000 RPM), have wide power ratings (up to 1200 HP), and run quietly.

A

true

193
Q

True or false:

Synchronous belts are virtually maintenance free

A

true

194
Q

What are 2 disadvantages of synchronous belts?

A
  1. not great for high shock loads
  2. do not provide overload protection (no slip
195
Q

On which type of belt is alignment more critical: V-belts or synchronous belts?

A

synchronous belts

196
Q

Which type of belt is more sensitive to dirt: V-belts or synchronous belts?

A

synchronous belts

197
Q

Do synchronous belts track or train well?

A

no

198
Q

What happens to synchronous belts when things go wrong?

A

they break

199
Q

What are the tensile members of synchronous belts usually made from?

A

twisted fibreglass cords

200
Q

What are the 2 main advantages of using twisted fibreglass cords in synchronous belts?

A
  1. minimal stretch
  2. holds its tension because the fibres do not stretch
201
Q

True or false:

Unlike gear teeth, the sprocket teeth of synchronous belts engage to the full depth of the grooves between the belt teeth with no root clearance

A

true

202
Q

How do synchronous belts transmit power?

A

the positive engagement between the teeth on the belt and the teeth on the sprocket

203
Q

True or false:

Synchronous belts will wander, even with accurately aligned sprockets.

A

true

204
Q

What needs to be included on the sprockets of synchronous belts to combat wander?

A

flanges

205
Q

What is the minimum number of flanges that needs to be included on sprockets on synchronous belts?

A

2 flanges

  • they can be on the same sprocket, or on opposite sides of two sprockets
206
Q

On other than vertical drives, why must there only be 2 flanges on sprockets that drive synchronous belts?

A

if more then 2 are used, the belt will climb up one flange and cut itself up

207
Q

What is the minimum arc of contact of a synchronous belt?

A

at least 60º and a minimum of 6 teeth

208
Q

What is ratcheting when it comes to synchronous belts?

A

teeth climbing out of engagement due to insufficient arc of contact/number of teeth engaged

209
Q

This type of synchronous belt design has teeth with flat sides.

A

trapezoidal teeth

210
Q

What are the 2 types of rounded tooth design found on synchronous belts?

A
  1. Rounded
  2. Parabolic (involute)
211
Q

When it comes to synchronous belts, which design has the stronger tooth form: trapezoidal or rounded?

A

rounded

212
Q

When it comes to synchronous belts, which design has the more energy efficient tooth design: trapezoidal or rounded?

A

rounded

213
Q

What is the pitch of a timing belt?

A

the distance from one tooth to the correspond point on the next tooth

214
Q

What is the tooth pitch distance of an L tooth pitch on a timing belt?

A

3/8”

215
Q

What do the first 3 numbers on a synchronous belt code represent?

A

pitch length, in inches

225 = 22.5”

216
Q

What does the letter after the pitch length number represent on a synchronous belt code?

A

the tooth pitch

L = 3/8”

217
Q

What do the 3 numbers after the tooth pitch letter represent on a synchronous belt code?

A

the width, in inches

075 = 0.75” or 3/4”

218
Q

What type of belts do normal synchronous belt codes not apply to?

A

Eagle belts, also known as helical offset tooth design belts

219
Q

True or false:

Tension timing belts enough to remove any slack from the unloaded span to ensure the teeth do not ratchet at startup

A

true

220
Q

True or false:

Tension synchronous belts until they are just snug enough to remove any clearance between the outside diameter of the sprocket teeth and the grooves between the belt teeth.

A

true

221
Q

What effect does the herringbone tooth pater on Eagle synchronous belts have on dirt?

A

its throws the dirt away from the mesh point of the belt, making it better at handling dirt

222
Q

What are the 3 parts of a pulley used in industrial machinery?

A
  1. rim
  2. web
  3. hub
223
Q

What are the 3 different design for the material that supports the rim on the hub of a pulley?

A
  1. web
  2. block
  3. arm
224
Q

What are 3 things that happen when a sub-minimum diameter sheave is selected to run with a belt?

A
  1. excessive bending stress in the under cord
  2. higher belt tensions
  3. run with higher temperatures
225
Q

What do the first 2 numbers on a synchronous belt sprocket code designate?

A

the number of grooves on the sprocket

  • treat these like teeth on a gear for ratio calculations
226
Q

What does the letter that comes after the first two digits on a synchronous belt sprocket code designate?

A

the tooth pitch

227
Q

What do the 3 numbers that come after the letter designation indicate on a synchronous belt sprocket code?

A

the width in inches

075 = 0.75” or 3/4”

228
Q

True or false:

Poly V-belt pulleys are similar to flat belt pulleys, except that there is no crown on the driving surface.

A

true

229
Q

What does the first number of a poly V-belt pulley code indicate?

A

the number of grooves

230
Q

What does the letter that comes after the first number in a poly V-belt code indicate?

A

the cross section

231
Q

What do the last two digits of a poly V-belt pulley code indicate?

A

the diameter of the pulley in inches

48 = 4.8”

232
Q

True or false:

With V-belt drive sheaves, the three groove angles (34º, 36º, and 38º) depend on the radius of the sheave.

A

true

233
Q

What are the 3 V-belt sheave groove angles?

A

34º, 36º, and 38º

234
Q

With a V-belt sheave, the groove width is specified by the width:

A

at the outside diameter of the pulley

  • the very top of the pulley
235
Q

True or false:

The groove width at the outside diameter of a V-belt sheave is used to determine the belt width.

A

true

236
Q

True or false:

The outside diameter of a V-belt sheave is used when determine the belt length.

A

true

237
Q

Can you interchange bushing on V-belt sheaves?

A

no

238
Q

This type of sheave bushing is slit through the barrel and flange and has no key in the OD of the barrel.

A

QD bushing

239
Q

Which type of synchronous belt is used in serpentine arrangements?

A

twin toothed belts

240
Q

Identify the following type of belt:

A

Standard wrapped V-belt

241
Q

Identify the following type of belt:

A

Cogged raw edged V-belt

242
Q

Identify the following type of belt:

A

Banded belts

243
Q

Identify the following type of belt:

A

Double V-belt

244
Q

Identify the following type of V-belt:

A

Fractional HP V-belt

245
Q

Identify the the following V-belt code:

3V355

A

3 ⟶ top width ⟶ 1/8” x 3 = 3/8”
V ⟶ high capacity belt
355 ⟶ length = 35.5”

246
Q

Identify the following type of belt:

A

Variable speed belt

247
Q

Identify the following belt code:

1228V255

A

Variable speed belt

248
Q

Identify the following type of belt:

A

Open ended belt

249
Q

Identify the following type of belt:

A

Link belts

250
Q

Identify the following type of belt:

A

Round belt

251
Q

Identify the cause of this damage on a V-belt:

A

Swell;

The belt has been exposed to excessive oil or grease resulting in the belt swelling, and the bottom envelope seam opening up.

252
Q

Identify the cause of the damage on this V-belt:

A

Caused by the belt being rolled onto the sheave

253
Q

Identify the cause of the damage on this V-belt:

A

Back tension

254
Q

Identify the following type of synchronous belt:

A

Twin toothed belt

255
Q

Identify the following parts of this synchronous belt code:

225L075

A

225 = pitch length 22.5”
L = tooth pitch L
075 = width 0.75” or 3/4”

256
Q

Identify the following information on a synchronous belt sprocket:

16L075

A

16 = number of grooves on the sprocket
L = tooth pitch L
075 = width 0.75” or 3/4”

257
Q

Identify the following information on a poly V-belt pulley code:

6L48

A
258
Q

Identify the following information from a V-belt sheave code:

QD4/3V6.00

A
259
Q

Belt _____________ is the loss of driving speed due to the lengthening and shortening of the belt as it cycles from the tight side to the slack side.

A

Creep

260
Q

Identify the following information of a poly V-belt:

180J6

A

180 = length in inches = 180”
J = section size = J
6 = number of ribs = 6

261
Q

Wide V-belt drives are energized to perform best at:

A

1:1 ratios

262
Q

Which type of V-belt gives the best crosswise rigidity?

A

wide belt series

263
Q

Why do V-belt drives have notches moulded into them on the narrow side?

A

to reduce the radius that they can wrap around

264
Q

How do manufacturers of variable speed V-belt drives prevent fretting corrosion?

A

with special coatings on the pulleys

265
Q

Mounting belt drives on a solid flat metal surface is important. Why?

A

the drives can become distorted if mounted on uneven surfaces

266
Q

True or false:

The convex sides of PIV pulleys are machined to have male and female tooth profiles.

A

true

267
Q

Hydraulic variable speed drives are _____________ (hydrodynamic/hydrostatic) in design.

A

hydrostatic

268
Q

True or false:

In a closed loop, variable speed hydraulic drive, the motor return oil goes directly to the reservoir.

A

false;

  • in a closed loop, the return directly feeds the motor
269
Q

Leakage oil in a closed loop, variable speed hydraulic drive is replaced by what device?

A

a charge pump

270
Q

Variable fill hydraulic drives use what device to remove oil from the unit while it is running?

A

a scoop tube

271
Q

How is pressure applied to the discs within a wet disc drive?

A

with a hydraulic piston

272
Q

What can happen during the overhaul of a wet disc hydraulic system if the discs are not matched marked and positioned properly during reassembly?

A

it can create a condition of dynamic unbalance

273
Q

What damage can be caused to a V-belt by using a sheave with variable diameter selections?

A

Ply separation caused by substandard sheave diameter

  • if the sheave is too small, the belt radius will be too tight, resulting in ply separation
274
Q

True or false:

The effective sheave diameter in a variable speed arrangement dictates the speed of the drive

A

True

Millwrong (27 decks)

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