Belts Flashcards
(152 cards)
1
Q
What type of drive are belt drives?
A
Friction drives
2
Q
What is a tensile members in terms of belts?
A
Cords that carry the load
3
Q
In terms of belts what transmits the power between the sheave and tensile member and support cords?
A
Compression material
4
Q
What is the purpose of the cover in terms of belts?
A
To protect the core of the belt
5
Q
How does a V belt transmit power? (2)
A
- friction between the sides of the belt and the sides of the sheave groove
- tensile members from the driver to the driven pulley
6
Q
What does the amount of power a belt can transmit depend on? (2)
A
-Strength of tensile member
-Grip of the belt on the pulley
7
Q
What does the amount of grip a belt has on a pulley depend on? (3)
A
-Arc of contact
-Tension applied to the belt
-Coefficient of friction
8
Q
Where is the pitch line located in terms of belts?
A
Through the load carrying zone
9
Q
Where should the pitch line of a belt be located on a sheave by industry standard during set up?
A
As close as possible to the outside diameter of the sheave
So the widest cross section of the belt Carries the load
10
Q
Define stretch in belts
A
The increase in length of a belt during its time in service
11
Q
In belt terminology 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 is defined as what?
A
Creep
12
Q
What takes place if creep extends all the way around a pulley?
A
Slip
13
Q
What is the arc of contact in belt terminology?
A
The number of degrees that a belt wraps around a pulley
14
Q
In belt terminology what is the number of degrees that a belt wraps around a pulley called?
A
Arc of contact
15
Q
What determines the tension on the belt?
A
The force between the belt and the pulley
16
Q
The gripping action on a V belt is entirely on the _______ of the belt and the ________ of the sheave groove
A
Sides
17
Q
In V belts the belt must NOT touch what part of the sheave?
A
The bottom
18
Q
What is the most widely used series of V belts?
A
Classical / standard series
19
Q
If a V belt is designated as A, B, C, D, or E what type of belt series does this indicate?
A
Classical / standard series
20
Q
Classical or standard series belts are designated with what?
A
A, B, C, D, or E
21
Q
What are A and B series belts commonly used for?
A
Single and multiple belt drives
22
Q
What are C, D, and E belts used in?
A
ONLY multiple belt drives
23
Q
What are the 5 main advantages of using a standard (classical) series belts
A
-High tolerance in poor conditions
-Reliability with infrequent maintenance
-reliability with unusual drive systems
-widest choices
-cover wraps around the entire belt
24
Q
What are the 4 variations of classical (standard) series belts?
A
-coffee raw edge
-banded (joined)
-double V
-fractional horsepower
25
How are cogged raw edged belts designated on labels?
AX, BC, CX
26
What are the 5 benefits of a cogged raw edged belt?
- greater flexibility
- enhanced airflow
- no covers on side and bottom
- fit sheaves more accurately
- higher friction
27
What is crucial with cogged edged belts? (2)
Cleanliness and sheave alignment
28
What is another name for banded belts?
Joined classical
29
What is another name for Double V belts?
Hexagonal belts
30
What type of belt is pictured?
Double V belt
31
What type of belt is pictured?
Banded belt
32
What type of belt is pictured?
Cogged raw edge belt
33
What are double V belts uniquely capable of?
Transmitting power on either side of serpentine drives
34
How are double V belts designated?
AA, BB, CC
35
What is another name for fractional horsepower belts?
Light duty belts
36
How are fractional horsepower belts designated?
2L, 3L, 4L, 5L
37
The first number in a classical belt designations is the number over fraction?
/8ths
Ex
4L2550
= 4/8 Light duty 25.5”
38
What is another name for high capacity V belts?
Narrow V belts
39
How are Narrow V belts designated?
3V, 5V, 8V
40
Why are narrow belts high capacity?
Due to their narrow wedge design it provides more support for the tensile members compared to classical
41
When tensioning high capacity V belts what should you keep in mind?
They require more tension than regular V belts
42
What is another name for Poly V belts?
V ribbed belts
43
How are Poly V belts designated?
J, K, L, and M
44
A belt designated as J, K, L, or M is what type of belt?
Poly V belt
45
What does the code for poly V belts provide? (3)
Length
Section
Number of ribs
46
What does belt 180J6 mean?
Poly V belt
180 inches
J size
6 ribs
47
When are variable speed belts used?
When speed changes are needed
48
What are the sides of variable speed belts called?
Flanges
49
What information is given in variable speed belt codes?
Top width
Groove angle
Cross section
Pitch length
50
What fractions are the first digits in a variable speed belt code out of?
/16th
51
What does the V belt code 1228V255 mean?
12/16
28 degrees
V shape
25.5”
52
What does a variable speed belt require?
Special sheaves
53
Where are link belts used?
In places/situations where it is difficult or impossible to install an endless belt
54
In round belt codes what does the first numbers indicate?
Diameter
55
What fraction is the round belts diameter given in?
/16ths
56
How do you check for wear on a sheave?
Sheave groove gauge
57
What is the MAXIMUM misalignment of a sheave?
1/16 inch per foot
58
What is the MAXIMUM runout of a sheave?
0.005 inches
59
Where is the slack side of a pulley system?
The side coming directly from the driver
60
Where should you NOT use idlers?
On reversing drives
61
What are outside idlers mainly used for?
Means of tensioning a belt
62
When using an outside idler what the MINIMUM size you should use?
1/3 larger than the smallest drive
63
Would you ever use a crowned outside idler?
No
64
Where should an outside idler be IDEALLY placed?
Slack side near the drive
65
What is the MAXIMUM speed of a cast iron sheave?
6500 feet/min
66
What is the MAXIMUM speed of a ductile Iron sheave?
9500 feet/min
67
What is the minimum speed a V belt can go?
1500 feet/min
68
What is the maximum speed a V belt can go?
9000 feet/min
69
What is the ideal speed of a V belt?
6500 feet/min
70
What is the formula for rim speed?
(Diameter x 3.14 x rpm) divided by 12
71
What is the MINIMUM centre of a drive and driven pulley?
The diameter of the largest sheave
72
What is the Maximum centre distance of a driven and drive pulley?
3 x the sum of both sheaves
OR
5 x the largest diameter
73
What is the max ratio of a V belt?
6:1
74
What is the maximum ratio for a cogged or small section belts?
7:1
75
Under ideal conditions what is the average belt life?
5000-7000 hours
76
Under ideal conditions what is the average life of a sheave?
25,000 hours
77
As a rule of thumb how often are belts replaced compared to sheaves?
Belts are replaced 4 x to one sheave replacement
78
If there is a larger and smaller sheave under the exact same conditions which one would wear first?
The smaller one
79
What is the MINIMUM arc of contact on the smallest (driven) pulley?
120 degrees
80
How is proper deflection calculated in a belt?
1/64” to every inch between centres
81
If you have a 40 inch centre distance what is the deflection for tensioning?
40/64
82
if you excessively tension a belt what will occur?
Wear in belt and bearings
83
After tensioning a belt when should you re check it?
12-24 hours
84
If you tighten a belt too loose what can occur?
Slip
Loss of power
Wear
85
What does it mean if the bottom of a sheaves groove is shinny?
Excessive wear needs to be replaced
86
What are the angles available for sheave grooves?
34-42 degrees
87
How much wear requires a sheave to be changed?
1/32 of an inch
88
What is the formula for calculating belt length between two pulleys?
[ Diameter (a) + diameter (b) ] x 3.14 +(2 x shaft centres)
89
If a smaller pulley is slipping what can you do?
Change to a smaller ratio ( 3:1 or 4:1)
90
What are the 3 constructions of a sheave?
Block
Webbed
Arm
91
What do notched belts provide compared to regular V or flat belts? (2)
Flexibility
Cooling
92
I’m wide V belts what do the ribs also provide?
Reinforcement
93
What is important when installing matched belts
That they are ALL new and ALL match
94
How much slippage is normal with V belts?
5%
95
How does the rigidity of a belt affect creep?
The more rigid the less creep
96
What is the typical angle of a V belt?
40 degrees
97
Where should you IDEALLY align sheaves?
From the inner edge
98
How should a V belt fit into a sheave?
Flush or a bit above the top, not touching the bottom
99
How are classic V belt lengths measured?
At the inside diameter
100
What does a V belt depend on to develop the proper friction?
The sides of the belt to grip the sides of the sheave
101
What type of belt is best when timing is important?
Toothed belt
102
What is an advantage of a friction belt drive over chain drives?
Belts are cheaper and require less maintenance
103
Which section of a V belt protects the belt from rust, weather, and harmful chemicals?
Cover
104
What is the most likely cause if a belt is slipping only under heavy load?
Not enough tension on belt
105
What 3 factors does a V belt depend on for grip?
Area of contact
Tension
Material of belt and pulley
106
Why is perforated or expanded metal popular in the fabrication of guards on a V belt drive?
To allow air circulation
107
What is the reason for a crowned pulley?
To centre the belt on a sheave
108
One of the purpose of an idler pulley is to ______________
Act as a belt take up adjustment
109
What is the typical crown on a 12 inch wide pulley?
1/8 inch
110
A standard or multiple belt series is also called ____________
Classical
111
A Belt coded 3L200 is what type of belt?
Fractional HP
112
What is an advantage of the cogged belt?
More flexible and provide better heat dissipation
113
A belt that is coded 3L200 is how many inches wide?
3/8
114
A belt having the code designation of 5V380 is how many inches wide?
5/8
115
A V belt has a centre distance of 96 inches, how much deflection must be in the belt?
1.5 inches
116
Which part of the V belt takes the load from one pulley to the other?
The tensile member
117
What is the minimal amount of arc contact for friction belt drives?
120 degrees
118
A new belt should be run how long before it is re tensioned?
12-24 hours
119
When will a double able V belt be used?
Sheaves are to be driven by the top and bottom of the belt
120
What belt has more tensile capacity in a given width?
Narrow V belt
121
Why would we use mechanical flat belt connectors?
Fast and cheap
122
What is the minimal amount of arc contact for a positive belt drive
60 degrees or 6 teeth
123
What is a main advantage of using V belts over chains?
Dampens vibrations
124
Where is the pitch line located in a power transmission belt?
Through the tensile members
125
What is the advantage of a vulcanized flat belt?
Gives the strongest joint
126
Variable speed drives typically use what belt?
Wide V belt
127
What type of belt is a 240L100
Positive drive type belt
128
What type of belt is a 650L4
Poly V belt
129
What is the most tolerant belt for misalignment?
Standard V belts
130
Why are standard V belts the best for misalignment?
Least loaded
131
What type of belt is a 3V450
High capacity
132
What is the ideal surface speed to run a V belt for optimal power transfer?
4500sfpm
133
How long is a rubber V belt in storage good for?
8 years and then it’s service life is expected to reduce
134
What type of belt is a 800-8M-30
Metric positive drive belt
135
How often should you re tension positive drive belts in service?
Only if noticeable slack, backlash, or ratcheting occurs
136
Why are we banding multiple series belt drive belts together?
Keeps them all at the same speed and wear rate
This also increases the strength and torque capacity of the belt
137
Where can a belt labeled A20(4L220) be used?
As a 20 inch standard or a 22 inch fractional hp belt
138
How do you get the correct deflection when you tension a belt?
Consult a chart for what pressure to apply to a belt and proper calculated deflection
139
How should a V belt properly fit into a sheave?
Almost flush or above the top not touching the bottom
140
How are classic V belts lengths measured?
At the inside diameter
141
A standard or multiple belt series is also called what?
Classical
142
A belt that is coded 3L200 is how many inches wide?
3/8
143
What belt has the most tensile capacity in a given width
Narrow V belt
144
What type of belt is a 800-8M-30
Positive drive type belt
145
Why are we banding multiple series belt drive belts together?
This keeps them all the same speed and wear rate
146
Besides keeping fingers out why is perforated sheet metal popular in fabrication of belt guards?
To keep them cooler
147
Variable speed drives typically use what belt?
Wide V belt
148
What type of belt is a 240L100
Positive drive type belt
149
What type of belt is a 650L4
Poly V belt
150
A 3V450 is what type of belt?
High capacity
151
Where can a belt labeled A20(4L220) be used?
As a 20 inch standard or 22 inch fractional hp belt
152
How do you get the correct deflection when you tension a belt?
Consult chart for pressure value to apply until proper deflection achieved
