Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Second Year Millwright > Belts And Chains > Flashcards

Belts And Chains Flashcards

0
Q

What are the limitations of v belts

A

Most designs operate with fixed center distance only, they have a minimum 120. ° arc of contact, they are unsuitable for positive drive requirements such as timing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What are the advantages of v belts?

A

They are cost-effective, there are highly reliable, no lubrication is required, they absorbs shock, they are quiet, and they can slip on overload to protect other components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the name of the part of the V-belt that carries the load?

A

The tensile members

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does the V-belt transmit power?

A

Friction between the sides of the belt and the sides of the sheave groove, the tensile members from the driver to the driven pulley

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What things determine the amount of power that A belt can transmit?

A

The strength of the tensile members, the grip of the belt on the pulley

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the minimum area of contact for a v belt?

A

120°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the pitch line?

A

The pitch line runs through the load carrying zone of the belt with the tensile members are located

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is belt creep?

A

Creep means the loss of driving speed due to the lengthening and shortening of the belt as it cycles from the slack side to the tight side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is belt slip?

A

When you have increased the load sufficiently the arc of creep extends all the way around the pulley and slip occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What problems does slip produce?

A

Power loss between the driver and driven pulleys, increase in belt and sheave groove wear, extra heat which degrades the belt material, the vibration transmitted to the bearings and seals results in a short life for the belts components.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What three things affect the grip between the belt in the pulley?

A

The coefficient of friction and, the arc of contact, the tension of the belt.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where must a vbelt never touch?

A

The v belt should never touch the bottom of the groove in the shiv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the designation for a classical series of vbelts?

A

A,B,C,D, or E

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the features of a classical series of v belt?

A

They have the highest tolerance for poor operating conditions, the most reliability where maintenance is infrequent, the most reliability for unusual drives such as Reverse bend, clutching, and quarter turn, and the whitest choice of belt and sheave sizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the designation for a cog raw edge belt?

A

AX, BX, CX

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the designation for a fractional horsepower belt?

A

2L,3L, 4L, 5L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the advantages of a called raw edge belt

A

They have greater flexibility and enhanced airflow which results in cooler operation. The cogs allow the belt to bend around sheaves with the smaller radius. The raw edges have no covers on the sides and bottom. Raw edge belts fit the sheaves more accurately than wrapped belts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are some limitations of cogged raw edge belts

A

They cannot be subjected to reverse bending, and they cannot be used on clutching drives, shock loads, or drives with changing center distances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is another name for a banded belt?

A

Joined classical belts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How are banded belts constructed?

A

They are constructed by joining two or more standard belts with a common backing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What issues are solved by using a banded belt?

A

Belt vibration, whip, and turnover

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How is alignment affected when using a banded belt?

A

Alignment is critical because these belts have less ability to flex sideways than individual belts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is another name for a double v belt?

A

Hexagonal belts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the designation for double v belt?

A

AA, BB, CC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
What type of drive our fractional horsepower belts used for?
Generally used for drives of less than 1 HP
25
What are fractional horsepower belts good for?
They are good for high speed
26
What is another name for a high capacity belt?
Narrow vbelts
27
Describe a high capacity vbelt
They are narrower and therefore have a larger area of contact on the sheave. They provide more support for the tensile members than classical v belts
28
What are the advantages of a high capacity v belt?
They are compact, which allows for use of a smaller diameter sheave, they have a higher power capacity than classical belts
29
What are some disadvantages of high capacity vbelts?
They require higher tension, therefore higher bearing loads, the higher side wall loading accelerates sheave wear in dirty or abrasive environments
30
What is the widths in a 3V, 5V. And 8V high capacity belt?
3/8", 5/8", and 1"
31
What is another name for a poly v belt?
Micro b
32
What is the designation for poly v belts?
J, K, L, M. H is also available for small sheaves and micro drives
33
What are some advantages of poly v belts?
They perform well on small diameter sheaves, ideal for high speed ratios, they can be used for reverse bends on serpentine belts, compact
34
What are the disadvantages of poly v belts?
They require special sheaves, high tension, and the alignment is more critical than for poly v belts
35
What are variable speed belts?
They run in sheaves with specially designed sides called flanges
36
Which variable speed setup has a changing center distance?
The single variable sheave. One flange is mechanically moved apart to permanently change the speed
37
Describe this code for a variable speed belt. | 12 28 V 255
Top width is 12/16(3/4), 28 is the groove angle, cross section is a v shape, and the pitch length is 25.5"
38
When can you adjust a variable speed drive?
You can only adjust the speed while the drive is running never when it is not turning
39
What is the use of open ended belting?
It is used as emergency replacements on the exact length of endless belt is not available.
40
What is the load capacity of a open ended belt?
They can only carry about one third of the loan of the corresponding endless belt.
41
What is a link belt, and what is it good for?
It can be used in situations where it is difficult or impossible to install an endless belt. It can also be used as an emergency replacement for an endless belt. It has the same power rating as a classic v belt from the same cross-section
42
What are some limitations of link belts?
They generate more vibration and endless belts, they cannot be used with back idlers, and they cannot be used with endless belts
43
Describe round belts
They have a round cross section, and multiple layers of tensile members through the center.
44
What are round belts generally used for?
They're suitable for quarter turn drives, serpentine drives, and are used for light duty fractional horsepower applications
45
What are the two ways to tell if a sheave is worn?
Use a sheave groove guard, or try a new belt in the sheave groove
46
What should you always do before installing a new belt?
Always back off the tension before you install it. Do not force any belt on to a sheave or pulley with a prybar or screwdriver
47
Why should you not use an impact wrench for tightening bolts?
She runs much straighter if the hub bolts are tight and evenly and alternately by hand
48
What is the purpose of idler pulley's?
The main reason is to increase the arc of contact. Increasing belt tension and preventing belt whip are two other reasons
49
Where can you not use idlers?
On reversing drives
50
What size and what location should be idler pulley be used
It should be at least 1.5 times the diameter of the smaller pulley and positioned as close as possible to the smaller sheave
51
What is another name for a contact idler
Kiss idler
52
When should you recheck tension of a belt after installation?
After 24 to 48 hours of operation
53
What is the maximum speed of a quarter turn drive?
2.5:1
54
How much is the horsepower rating De-rated in the quarter turn drive
It is De-rated by 90% of the normal rating
55
What does belt dressing do to a belt?
It degrades a belt material and shortens the belt life however it can be used in an emergency situation to avoid a machine outage at a critical time
56
What does belt whip mean?
It usually means that you should try increasing the tension of the belt. It can also mean that a belt is overloaded
57
At what temperature should you consider a belt that is heat treated?
Belts that reveal a temperature over 60°C
58
How should belts be stored?
They should be protected from moisture and temperature extremes, stored in their original package and out of direct sunlight, do not bend the belt or hang it on anything with the diameter of less than the smallest recommended pulley
59
What is a synchronous belt also called?
Timing belt, or positive drive belt
60
What are advantages of a synchronous belt drive?
- they last 3X as long as chain drive - less tension than classic belt - require no retensioning - no lubrication - wide speed range - virtually maintenance free
61
What are the disadvantages of a synchronous belt drive
They are more expensive than classic v belts, they do not provide overload protection by slipping, they require more accurate alignment then b belts
62
What are the tensile members made from in the synchronous belt?
They are twisted from fiberglass cords and sometimes aramid fiber is used
63
What is the arc of contact for a synchronous belt?
It must be a minimum angle of 60° or a minimum of six teeth engaged
64
Name some types of synchronous belts
Trapezoidal teeth, rounded tooth profile, twin tooth belt, helical offset tooth
65
What is another name for a twin toothed belt
A serpentine belt
66
Which belt is the highest power rating and the lowest noise rating in their belt line?
The helical offset to the design. It is also known as the Goodyear Eagle belt
67
225 L 075 belt. What does it indicate?
Pitch length 22.5" Tooth pitch L Width 0.75" or 3/4"
68
How much tension needs to be applied to a synchronous belt?
It requires just enough tension to remove any slack from the unloaded span
69
When do synchronous belts need to be retensioned?
Because the fiberglass 10 sound members do not stretch you never need to re-tension it
70
What must at least one sprocket have on it in a synchronous drive?
Flanges to guide the belt
71
What are the three types of hubs?
QD hub, taper bushing hub, taper lock hub
72
When you mount the hub with a keyless taper, how much contact area do you need between the tapered surfaces?
At least 85%
73
What kind of drive is a chain considered?
Positive drive
74
How efficient are chains?
98% or better
75
What are the three types of chains?
Roller chain silent chain and leaf chain
76
What are the two types of fits on master links?
Slip fit or pressfit. Slip fit reduces strength by 30%
77
What is different about heavy duty chain?
It has thicker sidebars to increase its resistance to fatigue, but does not have a higher load capacity
78
What are the two types of pre-lubricated chains
Sintered bushing, and O-ring chain
79
How are roller list chains designated?
There is a number five on the right-hand part of the chain number
80
What is another name for silent chain
Timing chain
81
What is another name for a serpentine drive chain?
Duplex
82
What must the straight edge touch when aligning sprockets?
Must touch at all four points of contact
83
How much sag is acceptable in slow to medium, and high speed drives.
Slow to medium drives is 4-6% on the non tensioned side and 2-3% on a higher speed drive
84
When should a chain be inspected for sag, after installation
After 8 hours of operation
85
What is the most important factor in controlling a chains wear?
Proper lubrication
86
Where should oil be put on a chain?
Between the plates on the unloaded side
87
What are the three methods of chain lubrication?
Manual or drip feed (low speed), bath lubrication (600-1500 fpm), forced lubrication (above 1500 fpm or heavily loaded drives)
88
When should a chain be replaced?
When it is elongated by 3% or more
89
What are the specs on these 2 chains? 70 25
70. =7/8 pitch roller chain | 25 = 2/8 pitch roller less chain
90
What must be specified when ordering a new sprocket?
Chain pitch, number of strands, hub style
91
What is recommended chain wrap angle?
120° however it can go as low as 90° can carry the full design load if proper chain tension is closely maintain
92
What are two ways to improve the wrap angle?
Increase the center distance, use a jack shaft to obtain the final ratio
93
What is a sprocket with an odd number of teeth
Hunting tooth sprocket
94
What are the three types of hub style sprockets?
Type A-mounts on any type of hub large hole Type B- hub one one side, Type C- hubs on both side for support Type D- split design. Allows you to replace sprocket without removing bearings
95
What are the attachments available for type a B and C sprockets?
Shear pin hubs, tapered for hubs, street for hubs, and keyless adapter also known as ring fetter
96
What does a Pratt and Whitney key look like?
An oval. It's like a square key with the corners rounded
97
What is the taper on a gib head key.
1/8" taper per foot
98
How is a woodruff key identified?
The first 2 numbers is width in 1/32" and second two is diameter in 1/8"
99
How is a QD hub recognizable?
They have an axial split through the barrel to the flange
100
What should key clearance not exceed?
.002-.005"
101
What is rule of thumb for key width??
1/4 the diameter of shaft
102
When should a gib head key not be used?
On a cast iron hub, as it could crack
103
When should you use a chamfered key and seat?
Large keys, high horsepower. Heavy shock loads
104
What are two types of links on a roller chain?
Roller link, pin link
105
Double strand chain is approx how much stronger than a single strand?
1.7 times

Second Year Millwright (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions