SEO Version
83
ELA-flex SD
™
For the initial drive selection, use the selection graphs illustrated
in the relative ELA-flex SD
™
cataloge section. For initial pulley
choice, it is recommended to use the driver pulley with maximum
diameter allowable in the application.
Safety factors
Belt selection is made according to a constant working load. In
case of peak loads and vibrations a safety factor c
1
must be con-
sidered.
Transmission with steady load
c
1
= 1,0
Transmission with peak or fluctuating loads:
Light
c
1
= 1,4
Medium
c
1
= 1,7
Heavy
c
1
= 2,0
For speed up driver factor c
2
must be considered:
i = from 0,66 to 1
c
2
= 1,1
i = from 0,40 to 0,66 c
2
= 1,2
i < 0,40
c
2
= 1,3
The resulting total safety factor is:
c
0
= c
1
·
c
2
The necessary data for drive calculation are:
• Power to be transmitted
P [kW]
• Driver rpm
n
1
[min
-1
]
• Motor starting torque
M
ab
[Nm]
• Required center distance
A [mm]
• Maximum driver pulley diameter d
w1
[mm]
Drive calculation
Select type of belt
Calculate drive ratio
Determine belt width
with
β [°] =
wrap angle
Calculate teeth in mesh
A drive is correctly tensioned when the belt slack side is ten-
sioned in all working conditions. It is also important to use
the minimum necessary tension to minimize shaft loads. Belt
tension is dependent also on belt length L
R
and its number of
teeth Z
R
. According to belt number of teeth, following tension
is suggested:
2 shafts drive
Z
R
< 75
F
TV
= 1/3 F
U
75
<
Z
R
< 150
F
TV
= 1/2 F
U
Z
R
> 150
F
TV
= 2/3 F
U
More than 2 shafts drive
F
TV
>
F
U
Determine installation tension
Verifiy allowable tensile load
Calculate shaft load
Belt lenght for drive with ratio i
#
1
Calculate belt lenght
Belt lenght for drive with ratio i = 1
and more precisely:
In order to ensure the correct drive installation tension, it is
recommended to use the special belt tension meter available
from ELATECH
®
.
driven
driver
n
n
i
=
tzA2 d A2 L
w
R
⋅ + ⋅ = ⋅π+ ⋅ =
( )
( )
2
k
g
k
g
R
t z z
A4
1
A2 z z
2
t
L
⎥
⎦
⎤
⎢
⎣
⎡
π
⋅
−
⋅
+ + + ⋅ ≈
( )
⎥
⎦
⎤
⎢
⎣
⎡
− ⋅⎟⎠
⎞
⎜⎝
⎛
β− + + ⋅ +β⋅
⋅
=
k
g
k
g
R
z z
180
1 z z
2
t
2
sin A2 L
k
e
z
360
z
⋅ β=
spez
e k
0
Mz z
cM 100
b
⋅
⋅
⋅ ⋅
=
(
)
1 i
F2 F
cos F2 F
Tv
Wsta
Tv
Wsta
=
⋅ =
β⋅
⋅
⋅ =
( )
⎥
⎦
⎤
⎢
⎣
⎡
⋅π⋅
− ⋅
⋅
⋅ =β
A 2
z z t
arccos
2
k
g
spez
e k
0
Pzz
c 1000 P
b
⋅
⋅
⋅
⋅ =
The allowable tensile load of the belt must be highter than the
total corrected peripheral force.
F
Tzul
> c
0
·
F
U
with
d
M 2000
F
W
U
⋅
=
for
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