Belts Flashcards
1
Q
____________ have a wedge shaped cross section.
A
V-belts
2
Q
How do V-belts transmit power?
A
by gripping the sides of a groove in a pulley
3
Q
What is the most cost effective means of power transmission:
A) V-belts
B) Gears
C) Chains
A
A) V-belts
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
5
Q
True or false:
V-belts are able to absorb shock.
A
true
6
Q
True or false:
The construction of V-belts allows for the belt to slip on overload.
A
true
7
Q
Do V-belts require lubrication?
A
no;
- lubrication actually degrades the V-belts gripping ability
8
Q
V-belts have a minimum of ______º arc of contact.
A
120º
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
10
Q
Can V-belts be used in areas of high ambient temperature?
A
no;
they degrade when exposed to high temperatures
11
Q
True or false:
V-belts are not practical for high surface speeds because of problems with dynamic balancing.
A
true
12
Q
What part of a V-belt construction consists of cords that carry the load?
A
the tensile members
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
14
Q
With a V-belt, the _______________ material transmits the power between the sheave and the tensile member and supports the cords.
A
compression
15
Q
True or false:
The compression material of a V-belt is often fibre-filled to provide transverse rigidity.
A
true
16
Q
On a V-belt construction, what purpose does the cover serve?
A
it protects the internal parts from wear and the environment
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
18
Q
The amount of power a V-belt can transmit depends on what 2 things?
A
- strength of the tensile members
- grip of the belt on the pulley
19
Q
What 3 things effect the grip of a V-belt on a pulley?
A
- arc of contact
- tension applied to the belt
- coefficient of friction between the belt and pulley
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
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
22
Q
What is the result of creep (not excessive)?
A
a slight belt flap on the return side
23
Q
True or false:
The flutter or flapping of a belt is normal.
A
true
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
25
What 4 negative effects does creep have on a V-belt arrangement?
1. loss of power between driver and driven pulleys
2. increased wear on belt and sheaves
3. additional heat (belt degradation)
4. excessive vibration
26
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.
true
27
True or false:
A V-belt can touch the bottom of the sheave groove.
false;
* if the V-belt touches the bottom of the sheave the sheave is excessively worn
28
What is the most widely used series of V-belt?
the classical or standard series
29
What are the designations of classical or standard V-belts?
A, B, C, D, and E
30
What is another name for multiple series V-belts?
classical or standard series
31
What type of V-belt has the highest tolerance for poor operating conditions?
classical or standard series
32
What type of V-belt would be selected for an application where maintenance is infrequent?
classical or standard series
33
True or false:
The classical series V-belt has the most reliability for unusual drives (reverse bend, clutching, and quarter turn).
true
34
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.
true
35
What 4 types of V-belt were developed from the classical series V-belt?
1. cogged raw edge
2. banded (joined classical belts)
3. double V
4. fractional HP
36
What belt code designation identifies a cogged raw edge V-belt?
X = cogged raw edge
* AX, BX, CX, etc.
37
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.
true
38
What effect do the cogs on cogged raw edged belts have on the belt bend radius?
the cogs allow the belt to make tighter bends
39
Which V-belt would have a smaller bend radius: a cogged raw edged belt or a classical series?
cogged raw edge;
* the cogs allow for a tighter bend radius
40
Which V-belt fits the sheaves more accurately: a cogged raw edged belt or a classical series?
cogged raw edge
41
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?
1. cogged raw edge
2. the higher coefficient of friction results in a smaller belt vs. a standard series
42
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?
no
43
True or false:
A cogged raw edged V-belt cannot be subjected to reverse bending.
true
44
True or false:
A cogged raw edged V-belt can be used in applications where some slip is required.
false;
they cannot be subject to slip
45
What is the cause of the limitations of cogged raw edged V-belts?
the aggressive mature of the grip of the belt
46
What are banded V-belts?
belts constructed by jointed two or more standard belts with a common backing
47
What other names are banded belts known under?
Power-band and joined classical belts
48
What 3 problems were joined classical belts developed to solve?
1. belt vibration
2. belt whip
3. belt turnover
49
Why is sheave alignment critical with banded belts?
banded belts have less ability to flex sideways than individual belts
50
True or false:
Banded belts have more power transmission ability when compared to the same number of individual belts.
false;
they have the same power transmission as the same number of individual belts
51
True or false:
Banded belts require more maintenance than individual V-belts.
true
52
What are the designations of banded belts?
B, C, D
* same as the classical seres belts
53
What types of belts would be designated AA, BB, and CC?
double V-belt
54
What is a hexagonal belt?
a double V-belt
55
This type of belt is a double-sided standard series V-belt.
a double V-belt
56
True or false:
Double V-belts are capable of transmitting power on both sides in serpentine drives
true
57
What type of V-belt is designated 2L, 3L, 4L, or 5L?
fractional HP V-belts
58
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.
true
59
True or false:
Fractional HP belts can go very fast.
true
60
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?
The top of the belt should be proud to the top of the sheave
61
What types of V-belts are designated 3V, 5V, and 8V?
high capacity V-belts
62
What are narrow V-belts?
the same as high capacity V-belts
63
What designations are used for high capacity V-belts?
3V, 5V, and 8V
64
What designations would be used with hexagonal belts?
AA, BB, and CC
65
What designations would be used for a fractional HP V-belt?
2L, 3L, 4L, and 5L
66
What design characteristic of a narrow V-belt increases its capacity?
the narrow wedge design provides more support for the tensile members
67
What are the 2 main advantages of high capacity V-belts when compared to classical series belts?
1. compact
2. higher power capacity
68
True or false:
High capacity V-belts are under tensioned if they are tensioned according to the same feel as classical V-belts.
true
69
What are the 2 main limitations of narrow V-belts?
1. require higher tension = higher loading on bearings
2. increased sheave wear in dusty and abrasive environments (due to higher side wall loading)
70
True or false:
Alignment and cleanliness are not important for high capacity belt drives.
false;
they are important
71
What is the top width of a 3V high capacity belt?
3V = 3/8"
* 1/8" x 3
72
What is the top width of a 5V high capacity belt?
5V = 5/8"
* 1/8" x 5
73
What is the top width of a 8V high capacity belt?
8V = 1"
* 1/8" x 8
74
True or false:
Worn sheaves affect the performance of joined high capacity belts more than classical banded belts.
true
75
What are the designations of poly V-belts?
J, K, L, and M
* also H for small sheaves and miniature drives
76
What are V-ribbed belts?
the same as poly V-belts
77
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.
Poly V-belt
78
With a poly V-belt, are the tensile members outside the pulley grooves, or inside of them?
outside
* the tensile members are on top of the pulley vs narrow V-belt which would be in the pulley groove
79
True or false:
Poly V-belts do not perform well on small diameter pulleys.
false;
they perform well on small diameter pulleys
80
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.
true
81
True or false:
Poly V-belts can be used with reverse bends or serpentine drives.
true
* found most often on automobiles as the timing belt
82
Why are poly V-belts ideal for high speed applications?
because their light weight and thin cross section
* heavier = more mass moving around = slower speeds
83
True or false:
Poly V-belts have a longer belt and sheave life due to equalized loading.
true
84
What are the 2 main limitations of poly V-belts?
1. require special sheaves and high tension
2. alignment is more critical
85
What 3 pieces of information do Poly V-belt codes contain?
1. length
2. section
3. number of ribs
180J6 = 180" x J size x 6 ribs
86
What types of belts are used where speed changes are needed?
variable speed belts
87
This types of belt runs in sheaves with specially designed sides.
variable speed belt
88
What are the sides of variable speed sheaves called?
flanges
89
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).
slowest
* this is the smallest space between the flanges, not the smallest diameter
90
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?
sheave ∅ ↓ = speed ↑
91
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?
sheave ∅ ↑ = speed ↓
92
What do the first 2 digits of a variable speed belt designation represent?
the top width, in 1/16"
12 = 12 x 1/16" = 12/16" = 3/4"
12 would be a 3/4" wide belt
93
What do the 3rd and 4th digits of a variable speed belt designation represent?
the groove angle
94
What do the last 3 digits of variable speed belt designation represent?
the pitch length of the belt
255 = 25.5"
95
What is the main advantage of a variable speed belt drive systems?
economical way of providing infinitely variable speed
96
What are the 2 main limitations of variable speed belt drive systems?
1. require special sheaves
2. not practical for very large HP
97
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?
1. the belts must be turning before adjusting the speed
2. the adjustment mechanism could be broken
98
What are two types of belts that can be cut to any length and fastened together?
1. open ended belts
2. link belts
99
What designations are used for open ended belts?
same cross section letter as standard belts (A, B, C, D, or E), but with VO after the letter.
100
What designation indicates an open ended belt?
VO
101
What is the main limitation of an open ended belt?
it can only carry 1/3 of the load that a corresponding endless belt could carry
102
What are the 2 main advantages of a link belt?
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
103
What are the 3 main limitations of link belts?
1. more vibration
2. cannot be used with back idlers
3. cannot be used with endless belts
104
What do the two numbers in a round belt designation indicate?
1st # = diameter, in 1/16" of an inch
2nd # = length
* 5 x 33 ⟶ 5 x 1/16" = 5/16" ∅ x 33" length
105
Identify the length and diameter of a round belt labelled 4 x 365.
4 ⟶ belt ∅ ⟶ 4 x 1/16" = 4/16" = 1/4" ∅
365 ⟶ length ⟶ 36.5"
106
True or false:
Round belts are suitable for quarter turn drives.
true
107
True or false:
Round belts are not suitable for serpentine drives.
false
108
True or false:
Round belts can be supplied as open-ended to allow for custom lengths to be cut and spliced.
true
109
What is the main limitation of a round belt?
light duty, fractional HP only
110
True or false:
The codes on most belts in North America are standardized by the Rubber Manufacturers Association (RMA).
true
111
What does the letter designate on an RMA belt designation code?
the shape and size of the cross section
112
What do the numbers that follow the letter designation on an RMA belt designation code stand for?
the length of the belt in inches
* the last digit of the length number is a decimal of an inch (255 = 25.5")
113
What 2 issues do dirt and deposits cause on belts and sheaves?
1. Wear - degradation through abrasion and corrosion
2. Vibration - imbalance which causes vibration
114
What are the two main reasons to inspect sheaves during cleanup?
1. to check for possible cracks, especially around the hub
2. check for dynamic balance
115
True or false:
X on belts indicates a cogged raw edge on both imperial and metric belts.
true
116
Where is belt length measured?
at the pitch line
117
What are the 2 ways to perform a wear check on belts and sheaves?
1. sheave groove gauge
2. check wear with a new belt
118
What causes a belt to swell?
excessive exposure to oil or grease
119
What effect does belt swell have on a belt?
the belt becomes soft, and the bottom envelope seam will "open up"
120
What do cut bottom and sidewalls indicate on a V-belt?
that the belt was pried overs the sheave during installation
121
What 2 things does fitting a belt involve?
1. aligning the sheaves
2. tensioning the belts
122
True or false:
Aligning the sheaves reduces vibration and extends belt life.
true
123
What is the maximum allowable misalignment of a V-belt?
1/16" offset per foot
124
With a belt and sheave arrangement, any runout that exceeds ________" should be corrected.
0.005"
* very difficult to achieve
125
What can happen when using tapered adapter bushings to mount sheaves and the bolts are not evenly tightened?
excessive runout
126
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.
true
127
What causes evenly spaced deep bottom cracks on a belt?
a substandard backside idler
128
How is deflection for belt tensioning checked on banded belts?
with a special deflection gauge that contacts the entire width of the belt
129
Why is the elongation method usually used to check the tension of banded belts?
the high forces required to check with the specialized deflection gauge
130
What is the elongation method for checking belt tension with banded belts?
uses an elongation table with a number (length multiplier) that indicates how long the belt should be under proper tension
131
Where can idler pulleys be located on belts?
either inside or outside the belt strands
132
Idlers are often added to belt systems for what 3 reasons?
1. increase belt tension
2. increase arc of contact
3. prevent belt whip
133
Should idlers be used on reversing drives?
no
134
When an outside idler is used to tension a belt, what type of pulley should be used for the idler?
a flat pulley at least 1.5 times the ∅ of the smaller pulley
135
When using an outside pulley to increase the arc of contact on a belt system, how should it be positioned?
as close as possible to the smaller sheave
136
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?
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
1. On which span should idler pulleys be located?
2. Why is this?
1. the slack span
2. it takes much less force to tension the slack span than drive span
138
Because an outside idler puts a backward bend on the belt, it leads to premature ____________ of the belt.
cracking
139
What effect does an inside idler have on the arc of contact of a belt?
it reduces it
140
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.
true
* no premature cracking due to bending the belt backwards
141
Why is a grooved pulley used on inside idlers?
better tracking
142
Where should an inside grooved idler be located?
on the slack side, at a point in the span that produces equal arcs of contact on the sheaves
143
Where should an inside flat idler be located?
away from the sheave the belt it is travelling towards to prevent unequal arcs of contact
144
What are contact idlers used for?
to counteract belt whip produced by long spans or shock loads
145
What is belt whip?
belt vibration in the vertical span
* this is where the belt is vibrating up and down
146
What are contact idlers also known as?
kiss idlers
147
How should outside kiss idlers be mounted in a pulley system?
located 1/3 of the span distance from the large pulley on the slack span
148
Should a kiss idler be set so that it creates a back bend in the belt?
no;
it should just "kiss" the top of the belt
149
What does an automatic take-up on a belt system consist of?
a spring on a movable mount or on an idler
150
What function does an automatic take-up perform in a belt system?
it maintains belt tension
151
1. What effect does an automatic take-up have on a belt?
2. How is the above achieved?
1. it increases the life of the belt
2. by providing uniform tension throughout the life of the belt (compensates for stretch)
152
True or false:
When tensioning belts, you have achieved the approximate tension when the belt springs back after being bump at mid-span.
true
153
If when bumped at mid-span and the belt does not spring back, its tension is too ___________ (tight/loose).
loose
154
If when bumped at mid-span and the belt feels like a solid board, it is too ____________ (tight/loose).
tight
155
Why is it a good idea to rotate the sheaves of a belts before checking the tension of said belt?
to ensure that belt is properly seating the sheave grooves
156
When installing belts, can new belts and old belts be used together on the same sheaves?
no
157
How long after initial installation should belt tension be rechecked?
during the first 24 to 48 hours
158
With belts, what is a quarter turn drive?
when power is transmitted from a horizontal shaft to a vertical shaft
159
What is the maximum speed ratio of a quarter turn belt drive?
2.5:1
160
1. When using a quarter turn drive belt arrangement, the centre distance must be at least:
2. Why is this distance required?
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
When using a quarter turn belt drive, where must the centreline of the horizontal shaft be located in relation to the vertical sheave?
it must be above the centreline of the vertical sheave
162
When using a quarter turn belt arrangement, the HP rating of the belt should be derated to ______%.
90%
163
What is the greatest concern when running a quarter turn belt drive arrangement?
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
With a belt system, start up checks should be repeated after how long after the initial start up?
24 to 48 hours
165
With a belt system, squealing sounds or the smell of burning rubber indicate:
a loose belt
166
With a belt system, flapping belts on the tight strand indicate:
misalignment
167
With a belt system, bearings running hotter than they did before the belt change indicate:
too much tension on the belts
168
With a belt system, increased amperage draw on an electric drive after the belt change indicates:
too much tension on the belts
169
With a belt system, excessive vibration can be caused by:
misalignment or runout
170
What should be used to clean a running belt?
brushes
* avoid entanglement
171
When tensioning a belt to compensate for stretch, how much tension should be added to the belt?
just enough to stop the slip
172
What could be the cause of slip if tensioning the belts do not eliminate it?
the belts and/or the sheaves grooves are worn
173
True or false:
Belt dressing should be used only as a last resort to avoid a machine outage at a critical time.
true
174
With a belt system, what is the cause of chirps?
dirt or dust in the sheave grooves or on the side of the belts
175
With V-belts, what is ride-out?
how high up on the sheave the belt rides
* as the sheave wears, the ride-out will decrease
176
What does squealing in a belt at start up or near maximum load indicate?
insufficient tension
177
If properly tensioned, what can a squealing belt indicate?
overload
178
What does belt whip on the tight span indicate on a belt drive system?
insufficient tension
179
What can be a cause of belts snaking?
runout or wobble on the sheaves
180
What is the maximum ambient temperature that normal belts should operate at?
60℃
181
If stored according to RMA recommendations, how long should belts last on the shelf?
8 years
182
What 4 things must be observed when storing belts according to RMA's recommendations?
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
What type of belt would be used where there can be no slip?
synchronous belts
184
Positive drive belts and timing belts are names for:
synchronous belts
185
This type of belt must be run in special pulleys called sprockets.
synchronous belts
186
This type of belt is a flat belt with moulded teeth that engage with a special pulley called a sprocket.
a synchronous belt
187
Synchronous belts last about _____ times longer than chain drives.
3 times
* minimum, may last longer
188
1. Which type of belt requires more tension: a classical V-belt or a synchronous drive?
2. Why is this?
1. synchronous drive
2. rely on mechanical engagement vs. coefficient of friction
189
Do synchronous belts require re-tensioning after start up?
no;
* they need never be re-tensioned
190
Do synchronous belts require lubrication?
no
191
Synchronous belts are ______% efficient.
98%
192
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.
true
193
True or false:
Synchronous belts are virtually maintenance free
true
194
What are 2 disadvantages of synchronous belts?
1. not great for high shock loads
2. do not provide overload protection (no slip
195
On which type of belt is alignment more critical: V-belts or synchronous belts?
synchronous belts
196
Which type of belt is more sensitive to dirt: V-belts or synchronous belts?
synchronous belts
197
Do synchronous belts track or train well?
no
198
What happens to synchronous belts when things go wrong?
they break
199
What are the tensile members of synchronous belts usually made from?
twisted fibreglass cords
200
What are the 2 main advantages of using twisted fibreglass cords in synchronous belts?
1. minimal stretch
2. holds its tension because the fibres do not stretch
201
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
true
202
How do synchronous belts transmit power?
the positive engagement between the teeth on the belt and the teeth on the sprocket
203
True or false:
Synchronous belts will wander, even with accurately aligned sprockets.
true
204
What needs to be included on the sprockets of synchronous belts to combat wander?
flanges
205
What is the minimum number of flanges that needs to be included on sprockets on synchronous belts?
2 flanges
* they can be on the same sprocket, or on opposite sides of two sprockets
206
On other than vertical drives, why must there only be 2 flanges on sprockets that drive synchronous belts?
if more then 2 are used, the belt will climb up one flange and cut itself up
207
What is the minimum arc of contact of a synchronous belt?
at least 60º and a minimum of 6 teeth
208
What is ratcheting when it comes to synchronous belts?
teeth climbing out of engagement due to insufficient arc of contact/number of teeth engaged
209
This type of synchronous belt design has teeth with flat sides.
trapezoidal teeth
210
What are the 2 types of rounded tooth design found on synchronous belts?
1. Rounded
2. Parabolic (involute)
211
When it comes to synchronous belts, which design has the stronger tooth form: trapezoidal or rounded?
rounded
212
When it comes to synchronous belts, which design has the more energy efficient tooth design: trapezoidal or rounded?
rounded
213
What is the pitch of a timing belt?
the distance from one tooth to the correspond point on the next tooth
214
What is the tooth pitch distance of an L tooth pitch on a timing belt?
3/8"
215
What do the first 3 numbers on a synchronous belt code represent?
pitch length, in inches
225 = 22.5"
216
What does the letter after the pitch length number represent on a synchronous belt code?
the tooth pitch
L = 3/8"
217
What do the 3 numbers after the tooth pitch letter represent on a synchronous belt code?
the width, in inches
075 = 0.75" or 3/4"
218
What type of belts do normal synchronous belt codes not apply to?
Eagle belts, also known as helical offset tooth design belts
219
True or false:
Tension timing belts enough to remove any slack from the unloaded span to ensure the teeth do not ratchet at startup
true
220
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.
true
221
What effect does the herringbone tooth pater on Eagle synchronous belts have on dirt?
its throws the dirt away from the mesh point of the belt, making it better at handling dirt
222
What are the 3 parts of a pulley used in industrial machinery?
1. rim
2. web
3. hub
223
What are the 3 different design for the material that supports the rim on the hub of a pulley?
1. web
2. block
3. arm
224
What are 3 things that happen when a sub-minimum diameter sheave is selected to run with a belt?
1. excessive bending stress in the under cord
2. higher belt tensions
3. run with higher temperatures
225
What do the first 2 numbers on a synchronous belt sprocket code designate?
the number of grooves on the sprocket
* treat these like teeth on a gear for ratio calculations
226
What does the letter that comes after the first two digits on a synchronous belt sprocket code designate?
the tooth pitch
227
What do the 3 numbers that come after the letter designation indicate on a synchronous belt sprocket code?
the width in inches
075 = 0.75" or 3/4"
228
True or false:
Poly V-belt pulleys are similar to flat belt pulleys, except that there is no crown on the driving surface.
true
229
What does the first number of a poly V-belt pulley code indicate?
the number of grooves
230
What does the letter that comes after the first number in a poly V-belt code indicate?
the cross section
231
What do the last two digits of a poly V-belt pulley code indicate?
the diameter of the pulley in inches
48 = 4.8"
232
True or false:
With V-belt drive sheaves, the three groove angles (34º, 36º, and 38º) depend on the radius of the sheave.
true
233
What are the 3 V-belt sheave groove angles?
34º, 36º, and 38º
234
With a V-belt sheave, the groove width is specified by the width:
at the outside diameter of the pulley
* the very top of the pulley
235
True or false:
The groove width at the outside diameter of a V-belt sheave is used to determine the belt width.
true
236
True or false:
The outside diameter of a V-belt sheave is used when determine the belt length.
true
237
Can you interchange bushing on V-belt sheaves?
no
238
This type of sheave bushing is slit through the barrel and flange and has no key in the OD of the barrel.
QD bushing
239
Which type of synchronous belt is used in serpentine arrangements?
twin toothed belts
240
Identify the following type of belt:
Standard wrapped V-belt
241
Identify the following type of belt:
Cogged raw edged V-belt
242
Identify the following type of belt:
Banded belts
243
Identify the following type of belt:
Double V-belt
244
Identify the following type of V-belt:
Fractional HP V-belt
245
Identify the the following V-belt code:
3V355
3 ⟶ top width ⟶ 1/8” x 3 = 3/8”
V ⟶ high capacity belt
355 ⟶ length = 35.5”
246
Identify the following type of belt:
Variable speed belt
247
Identify the following belt code:
1228V255
Variable speed belt
248
Identify the following type of belt:
Open ended belt
249
Identify the following type of belt:
Link belts
250
Identify the following type of belt:
Round belt
251
Identify the cause of this damage on a V-belt:
Swell;
The belt has been exposed to excessive oil or grease resulting in the belt swelling, and the bottom envelope seam opening up.
252
Identify the cause of the damage on this V-belt:
Caused by the belt being rolled onto the sheave
253
Identify the cause of the damage on this V-belt:
Back tension
254
Identify the following type of synchronous belt:
Twin toothed belt
255
Identify the following parts of this synchronous belt code:
225L075
225 = pitch length 22.5”
L = tooth pitch L
075 = width 0.75” or 3/4”
256
Identify the following information on a synchronous belt sprocket:
16L075
16 = number of grooves on the sprocket
L = tooth pitch L
075 = width 0.75” or 3/4”
257
Identify the following information on a poly V-belt pulley code:
6L48
258
Identify the following information from a V-belt sheave code:
QD4/3V6.00
259
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.
Creep
260
Identify the following information of a poly V-belt:
180J6
180 = length in inches = 180”
J = section size = J
6 = number of ribs = 6
261
Wide V-belt drives are energized to perform best at:
1:1 ratios
262
Which type of V-belt gives the best crosswise rigidity?
wide belt series
263
Why do V-belt drives have notches moulded into them on the narrow side?
to reduce the radius that they can wrap around
264
How do manufacturers of variable speed V-belt drives prevent fretting corrosion?
with special coatings on the pulleys
265
Mounting belt drives on a solid flat metal surface is important. Why?
the drives can become distorted if mounted on uneven surfaces
266
True or false:
The convex sides of PIV pulleys are machined to have male and female tooth profiles.
true
267
Hydraulic variable speed drives are _____________ (hydrodynamic/hydrostatic) in design.
hydrostatic
268
True or false:
In a closed loop, variable speed hydraulic drive, the motor return oil goes directly to the reservoir.
false;
* in a closed loop, the return directly feeds the motor
269
Leakage oil in a closed loop, variable speed hydraulic drive is replaced by what device?
a charge pump
270
Variable fill hydraulic drives use what device to remove oil from the unit while it is running?
a scoop tube
271
How is pressure applied to the discs within a wet disc drive?
with a hydraulic piston
272
What can happen during the overhaul of a wet disc hydraulic system if the discs are not matched marked and positioned properly during reassembly?
it can create a condition of dynamic unbalance
273
What damage can be caused to a V-belt by using a sheave with variable diameter selections?
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
True or false:
The effective sheave diameter in a variable speed arrangement dictates the speed of the drive
True
