Pulley-select.pdf
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Sandvik Conveyor Components 5/2000
SELECTION OF CONVEYOR PULLEY 1
CAPACITY- AND POWER CALCULATIONS
Specify:
Selecting the conveyor pulleys is started by specifying the belt tensions of the conveyor. Belt tensions come from the capacity calculations of the conveyor. Calculations can be made according to SFS-ISO5048. Specify the belt tensions F and wrap angle a for each pulley. Capacity and power calculations also give the correct belt width B. Generally the belt specifies the minimum diameter of the pulley. Select the diameter.
Wrap angle a Belt width B Method of belt strain Belt tensions F Pulley diameters Use following pages as help: Belt tensions and friction/ Pulley diameter Optimization examples of the pulley size
We will help you with the calculations if needed.
Make the capacity- and power calculations
Use as help the pages
Estimate tentatively wrap angle a friction coefficient m
Belt tensions and friction/Pulley diameter Optimization examples of the pulley size Pulley laggings
Calculate tentative belt tensions
Optimize the belt tensions of the pulley
Decide wrap angle a friction coefficient m Calculate the final results of belt tensions
R = F1 + F2
F1 µα =e F2
R = 2 × F3
R = G × tan (α / 2)
2
R = G × tan (α / 2)
R =G
R = F2 × tan (α / 2)
SPECIFY THE RESULTANT LOAD OF THE PULLEY The resultant load R is specified on the basis of the belt tensions. Specify own resultant load R for each pulley with the help of belt tensions and general calculation methods.
Calculate: Resultant R
The obtained resultant load R has to be corrected in the following cases: SCREW TAKE-UP:
When there is a screw take-up on the conveyor, the resultant load R of tail pulley has to be multiplied by the safety factor 1.5. R = 1.5 x R(of the belt tensions)
SMALL WRAP ANGLE a: If the calculated resultant load R of tail pulley exceeds 50 kN and the wrap angle a is less than 75 degrees, extra tension is placed on the pulley shell. ROXON's technical service helps you to select the correct pulley. Select the pulley according to the corrected resultant load. We reserve the right for modifications without prior notice.
Sandvik Conveyor Components 5/2000
3
SELECTION OF THE PULLEY TYPE AND SEALING The ROXON pulley range is very versatile. Selection of our standard pulleys contain the most general constructional alternatives among our customers. They have been optimized to the functional constructions on the economical, strength and technical basis. We design and tailor make pulleys also exclusively acc. to your special needs. Select the pulley type.
Use the pages: Standard pulleys Pulley bearing and sealing methods
Note that the loadability of each pulley types is different on the same shaft diameters. Bearing house sealings of our standard pulleys are designed to give long operational lifetime when running the conveyor in normal environments. However, sometimes it is advantageous to select some other sealing method from our wide selection. Check the suitability of the standard sealing.
4 5 6
SELECTION OF THE PULLEY SIZE (SHAFT DIAMETERS) The max. load RT for each pulley type and size is given on the data pages relating to of our standard pulleys. Select the pulley size (shaft diameter) suitable for your belt width so that the calculated resultant load R is smaller than the allowed load RT of the pulley.
Use the pages: DL, BL, DK, ...
CHECK THE BEARING LIFE AND ROTATION SPEED Check the bearing life for the selected pulley according to the Bearing life and need for a balancing -page. If the bearing life is below the resultant load R, select the next pulley size with a larger shaft diameter. Check the bearing life and need for a balancing.
Use the page: Bearing life and need for a balancing
OTHER PULLEY SIZES When the load exceeds the loading range of the standard pulley selection, the pulleys must be tailor made. SELECTION EXAMPLE OF THE DRIVE PULLEY:
SELECTION EXAMPLE OF THE TAIL PULLEY:
Select the drive pulley according to the following initial information:
Select the tail pulley according to the following initial information:
Calculated resultant Wrap angle Belt speed Belt width Pulley diameter Expected bearing life
Calculated resultant Wrap angle Belt speed Belt width Pulley diameter Expected bearing life Belt tensioning
R a v B D
= = = = =
18 kN 180 ° 1.8 m/s 1200 mm 500 mm 50 000 h
R a v B D
= = = = =
8 kN 180 ° 1.2 m/s 1200 mm 400 mm 50 000 h Screw take-up
In the example resultant load need not be corrected due to the wrap angle (a) and screw take-up. Select the pulley according to resultant R = 18 kN.
In the example resultant load need not to be corrected due to the wrap angle (a). Due to screw take-up, selection of the pulley according to resultant R = 1.5 x 8 = 12 kN.
Pulley type selected is from the DK -serie.
Pulley type selected is from the BK -serie.
From the data sheet of DK-, BK-pulley, from the table Loadability of the pulley RT , the following pulley is selected:
From the data sheet of DK-, BK-pulley, from the table Loadability of the pulley RT , the following pulley is selected:
DK60 - 500X - 1400
BK50 - 400T - 1400
Base: R < RT (18 kN < 21 kN)
Base: R < RT (12 kN < 13 kN)
On the basis of pulley diameter D , belt speed v and expected life from the page heated Bearing life and need for a balancing gives for the DK60 -pulley:
On the basis of pulley diameter D , belt speed v and expected life from the page heated Bearing life and need for a balancing gives for the BK50 -pulley:
RL = 71 kN
RL = 50 kN
Because R < RL (21 kN < 71 kN), selected pulley is accepted.
Because R < RL (12 kN < 50 kN), selected pulley is accepted.
ORDERING EXAMPLE:
ORDERING EXAMPLE:
DK60 - 500X - 1400, for the gear Kumera RF125
BK50 - 400T - 1400
We reserve the right for modifications without prior notice.
Sandvik Conveyor Components 5/2000
BELT TENSIONS AND FRICTION PULLEY DIAMETER BELT TENSIONS AND FRICTION The friction coefficient of the drive pulley surface is of decisive importance for the power transmission between the conveyor drive and the belt. The friction coefficient is influenced not only by the environmental and operational conditions but also essentially the used lagging material on the pulley.
Using good, friction increasing lagging also has an important effect on the pulley size. Study carefully the lagging alternatives on the Pulley laggings -page.
The power and periphery force transferred with the pulley is calculated with the following formulas:
Fu = F1 − F2
PA = Fu × v
The friction coefficient is of importance to the ratio between the belt tensions:
F1 = e µα F2
F2 ≥ Fu ×
1
e
µα
−1
m=
= Fu × m
1
e
µα
−1
Coefficient m is called factor of power transmission. The table below shows the factor value with some m and a values. Wrap an g le a°
0.10 2.895 2.709 2.543 2.394 2.259 2.136 2.024 1.922 1.828 1.144 1.102 1.063 1.025 0.990 0.957 0.894 0.838
170 180 190 200 210 220 230 240 250 360 370 380 390 400 410 430 450
0.15 1.784 1.661 1.552 1.453 1.364 1.284 1.211 1.144 1.082 0.638 0.612 0.587 0.563 0.541 0.519 0.480 0.445
0.20 1.234 1.144 1.063 0.990 0.925 0.866 0.812 0.763 0.718 0.398 0.379 0.361 0.345 0.329 0.314 0.287 0.262
FAC TOR OF P OWE R TR AN S MIS S ION m F rictio n co efficien t o f th e d riv e p u lley 0.30 0.35 0.40 0.697 0.548 0.439 0.638 0.499 0.398 0.587 0.456 0.361 0.541 0.418 0.329 0.499 0.384 0.300 0.462 0.353 0.274 0.428 0.325 0.251 0.398 0.300 0.230 0.370 0.277 0.212 0.179 0.125 0.088 0.168 0.116 0.082 0.158 0.109 0.076 0.149 0.102 0.070 0.140 0.095 0.065 0.132 0.089 0.061 0.118 0.078 0.052 0.105 0.068 0.045
0.25 0.909 0.838 0.775 0.718 0.667 0.621 0.579 0.541 0.506 0.262 0.248 0.235 0.223 0.212 0.201 0.181 0.163
a ~ 120° ... 180°
a ~ 210° ... 250°
0.45 0.357 0.321 0.290 0.262 0.238 0.216 0.197 0.179 0.163 0.063 0.058 0.053 0.049 0.045 0.042 0.035 0.030
PA
=
power transmitted with the pulley required periphery force
Fu
=
v
=
conveyor speed
F1
=
belt tension on the incoming side
F2
=
belt tension on the outgoing side
e
=
radix 2.718 of the natural logarithm
m
=
coefficient of friction on the pulley
a
=
wrap angle of the belt on the pulley (rad)
R
=
resultant load
0.50 0.293 0.262 0.235 0.212 0.190 0.172 0.155 0.140 0.127 0.045 0.041 0.038 0.034 0.031 0.029 0.024 0.020
a ~ 360° ... 400°
0.55 0.243 0.216 0.192 0.172 0.154 0.138 0.124 0.111 0.100 0.033 0.030 0.027 0.024 0.022 0.020 0.016 0.013
0.60 0.203 0.179 0.158 0.140 0.125 0.111 0.099 0.088 0.079 0.024 0.021 0.019 0.017 0.015 0.014 0.011 0.009
a ~ 410° ... 450°
PULLEY DIAMETER Always check the minimum diameter of the pulley according to the belt type because the overlay of the different manufacturers varies and needs a different minimum diameter. Standards (SFS, ISO 368476) specifies the min. diameters of the pulleys for each type of belt according to the operating data. The table enclosed shows the min. diameters of the most common EP -type belts. Besides the enclosed examples of EP-belt with polyesther fabric there are also vinyl-nylon and steel wire belt as well as patterned- and ribbed belts which all need checking according to the brochures of the belt manufacturers. R e c o mme n d e d min imu m d ia me te r o f th e p u lle y P e rc e n ta g e (% ) o f b e lt te n s io n d u rin g c o n v e y o r ru n fro m ma x imu m a llo we d te n s io n
F ra me ty p e o f th e E P -fa b ric b e lt
160/2 200/2
( 60 ) - 100 %
( 30 ) - 60 %
30 %
L o c a tio n o f th e p u lle y
L o c a tio n o f th e p u lle y
L o c a tio n o f th e p u lle y
A
B
C
A
B
C
A
B
C
250
200
160
200
160
125
160
160
125
250
200
160
200
160
125
160
160
125
320
250
200
250
200
160
200
200
160
250/2
315/3
315/2
400/3
500/3
400/2
630/4
500/4
630/5
800/4
1000/3
800/5
1250/4 1000/4
1000
1000/5 1600/4 1600/5
630/3
400
320
250
320
250
200
250
250
200
500
400
320
400
320
250
320
320
250
630
500
400
500
400
320
400
400
320
800
630
500
630
500
400
500
500
400
800
630
800
630
500
630
630
500
Better friction and more power for transmission can not be achieved by enlarging the pulley diameter. Only if the preliminary selection has been too small a pulley diameter for the stiff belt, can enlarging the pulley diameter increase the friction between drive pulley and belt.
A
=
B C
= =
drive pulleys or other pulleys with heavy belt tensions freely rotating tail pulleys freely rotating tail pulleys with wrap angle less than 30 degrees
BELT CODE:
EP 800 / 5
Fabric type (EP = polyesther) Tensile strength at break of the belt N/mm2 Number of plies We reserve the right for modifications without prior notice.
Sandvik Conveyor Components 5/2000
OPTIMIZATION EXAMPLES OF THE PULLEY SIZE The coefficient of friction and wrap angle of the drive pulley have an essential influence on the component selection of a belt conveyor. The pulley laggings which increase the friction will decrease tensions considerably.
The enclosed study covers only the main components of transmission; comparison of the pulleys and belt. Considerable savings will also be reached with other conveyor components and frame structures by reducing the belt tensions.
Example conveyor:
Among other things by limiting the belt sag the belt stress will increase a little in example 3.
Belt width B Conveyor length Capacity Belt speed Conveyed material Conveyor type Take-up method
1200 mm 70 m 450 t/h 1.0 m/s ore ascending conveyor gravity take-up
The prices below described ratio of financing costs between different kinds of conveyor solutions.
COEFFICIENT OF FRICTION
WRAP ANGLE
In the following examples the effect of the coefficient of friction on the belt tensions and selection of the main components has been compared. Used wrap angle a = 180°.
In the following examples the effect of the wrap angle on the belt tensions and selection of the main components has been compared. Used friction cofficient m = 0.3.
Example 1
m = 0.1
Example 1
a = 180°
Required Belt width Wrap angle
Fu = 31 kN B = 1200 mm a = 180°
Required Belt width Friction cofficient
Fu = 31 kN B = 1200 mm m = 0.3
F2 = F u F1 = F u R = F1
x + +
F2 = Fu F1 = Fu R = F1
x + +
m = 31 x 2.709 = 84 kN F2 = 31 + 84 = 115 kN F2 = 115 + 84 = 199 kN
F3 = 81 kN ® R = 2
x
m = 31 F2 = 31 F2 = 51
0.638 = 20 kN 20 = 51 kN 20 = 71 kN
F3 = 17 kN ® R = 2
F3 = 162 kN
Cost comparison of the components: 1. Drive pulley: 2. Tail pulley: 3. Belt:
x + +
x
F3 = 34 kN
Cost comparison of the components:
DK140 - 800T - 1400 BK135 - 630T - 1400 EP1000/5
21 660 mk 16 670 mk 67 500 mk
Total:
105 830 mk
1. Drive pulley: 2. Tail pulley: 3. Belt:
DK100 - 500X - 1400 BK80 - 400K - 1400 EP500/4
10 875 mk 6 210 mk 43 800 mk
Total:
60 885 mk
Example 2
m = 0.3
Example 2
a = 210°
Required Belt width Wrap angle
Fu = 31 kN B = 1200 mm a = 180°
Required Belt width Friction cofficient
Fu = 31 kN B = 1200 mm m = 0.3
F2 = F u F1 = F u R = F1
x + +
F2 = Fu F1 = Fu R = F1
x + +
m = 31 F2 = 31 F2 = 51
0.638 = 20 kN 22 = 51 kN 20 = 71 kN
x + +
F3= 17 kN ® R = 2
F3
x
= 34 kN
m = 31 F2 = 31 F2 = 46
0.499 = 15 kN 15 = 46 kN 15 = 61 kN
F3 = 13 kN ® R = 2
Cost comparison of the components: 1. Drive pulley: 2. Tail pulley: 3. Belt:
x + +
x
F3 = 26 kN
Cost comparison of the components:
DK100 - 500X - 1400 BK80 - 400T - 1400 EP500/4
10 875 mk 6 220 mk 43 800 mk
Total:
60 895 mk
1. 2. 3. 4.
Drive pulley: Tail pulley: Snub pulley: Belt:
DK90 - 400X - 1400 BK70 - 320T - 1400 BK50 - 270K - 1400 EP500/3
8 560 5 090 4 670 40 300
Total:
58 620 mk
Example 3
m = 0.6
Example 3
a = 250°
Required Belt width Wrap angle
Fu = 31 kN B = 1200 mm a = 180°
Required Belt width Friction cofficient
Fu = 31 kN B = 1200 mm m = 0.3
F2 = F u F1 = F u R = F1
x +
F2 = Fu F1 = Fu R = F1
x + +
m = 31 F2 = 31 F2 = 37
x + +
F3 = 3 kN ® R = 2
0.179 = 6 kN 6 = 37 kN 6 = 43 kN x
F3
= 6 kN
+
m = 31 F2 = 31 F2 = 42
+
F3 = 9 kN ® R = 2
Cost comparison of the components: 1. Drive pulley: 2. Tail pulley: 3. Belt:
x +
mk mk mk mk
0.370 = 11 kN 11 = 42 kN 11 = 53 kN x
F3
= 18 kN
Cost comparison of the components:
DK80 - 400Z - 1400 BK40 - 320T - 1400 EP315/3
9 610 mk 3 410 mk 30 000 mk
Total:
43 020 mk
1. 2. 3. 4.
Drive pulley: Tail pulley: Snub pulley: Belt:
DK90 - 400X - 1400 BK60 - 320T - 1400 BK50 - 270K - 1400 EP400/3
8 560 4 540 4 670 36 000
mk mk mk mk
Total:
53 770 mk
We reserve the right for modifications without prior notice.
Sandvik Conveyor Components 1/98
PULLEY LAGGINGS There is a wide range of different laggings on ROXON pulleys depending on weather-, process- and operation environments. When selecting the laggings please note that their purposes on the drive- and tail pulleys are different and so lagging should be considerated separately. In addition to the lagging range, other laggings are also available for special needs.
Tail pulley on clean side of belt
Tail pulley on dirty side of belt Clean side of belt
Dirty side of belt
Tail pulley on clean side of belt
Drive pulley:
Tail pulley:
The main purpose of the lagging is to increase the friction and so improve the transmission between the belt and the pulley.
On the dirty side of the belt lagging helps the pulley to remain clean and so to keep the belt centered.
Elastic laggings also help to keep the pulley clean and so improve the duration of friction. Grooved lagging makes possible the removal of moisture at the point where the belt comes to the pulley and thus improves the friction.
LAGGING TYPE
Steel surface no separate laggings
Operating target
Type
The cleanness of the tail pulley can be considerably improved by using separate pulley cleaners.
Environments
Price ratio
Friction coefficient on drive pulley Dry
Slightly moist
Wet, dirty ice
0
0.4
0.15
R, bearing of the pulley will last the required length of time.
r.p.m of drum (1/min)
BED, BEE, BP 40 DL, DK, BL, BK 40
Table 1
Life h
k
DL, DK, BL, BK 50
10 000
1.32
BED, BEE, BP 60
16 000
1.15
20 000
1.07
25 000
1.00
32 000
0.93
DL, DK, BL, BK 80
50 000
0.81
BED, BEE 120
63 000
0.76
BED, BEE 100 DL, DK, BL, BK 90
80 000
0.71
100 000
0.63
BED, BEE, BP 50
Loading of drum bearings RL (kN)
DL, DK, BL, BK 60 BP 70 BED, BEE, BP 80 DL, DK, BL, BK 70
BED, BEE 140 DL, DK, BL, BK 100 DL, DK, BL, BK 110 DL, DK, BL, BK 125 DL, DK, BL, BK 115 DL, DK, BL, BK 135 DL, DK, BL, BK 140
Larger pulley sizes are dimensioned separately case by case
We reserve the right for modifications without prior notice.
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