MOTOVARIO
For correctly selecting a gear reducer or geared motor, several essential pieces of data are required:
1. The rotational input speed to the gear reducer
(n1)
and the rotational output speed
(n2).
Through these two values it is possible to calculate the reduction ratio
(i)
of the gear reducer using the
following formula:
i=n1/n2
2. The torque required by the application
(Mr2)
.
The geared motor or gear reducer can be selected once this data is known.
This guide helps you to select the right product in just a few steps:
Geared motor selection
1. Determine the application’s actual service factor
(s.f.)
. This parameter depends on the type of load of the
powered machine, the number of starts per hour and the hours of operation (refer to the “Service factor”
paragraph)
2. Calculate the input power
Pr1
using the required torque value
Mr2
, the speed
n2
and dynamic efficiency
value.
Pr1=(Mr2*n2)/(9550*
η
d).
The dynamic efficiency value depends on the type of gear reducer and
on the number of gear reduction stages. (To calculate the efficiency value see its page).
3. Consult the geared motor performance tables and identify a normalised power value
Pn1
exceeding the
required power
Pr1
, such that:
Pn1
≥
Pr1
4. Once the suitable nominal power has been identified, select the geared motor capable of generating the
rotational speed closest to the desired n2 value and with service factor s.f. greater or equal to that
required by the application.
For Atex product selection, use the service factor “f.s.Atex”.
In the geared motor selection tables the combinations include 2-pole, 4-pole and 6-pole motors
powered at 50Hz; for different drive speeds refer to the nominal data provided for the gear reducers.
Gear reducer selection
1. Determine the application’s service factor
(s.f.)
(consult to the “Service factor” paragraph on its page) .
2. Calculate the reduction ratio i from the requested output speed
n2
and from the input speed
n1.
i=n1/n2
3. Calculate the torque
Mc2
for selecting the gear reducer through the torque required by the
application
Mr2
and the service factor s.f.:
Mc2=Mr2*(f.s.)
4. Consult the Gear Reducer Performance tables looking for the reducer that, with the reduction ratio closer
to the calculated one, has a nominal torque
M2
so that:
M2
≥
Mc2
For Atex product Selection, refer to Atex Gear Reducer Performance tables.
Checks
Once the gear reducer or geared motor has been selected, the following checks should be performed:
A.
Thermal power
The gear reducer’s thermal power must be equal to or greater than the installed mechanical power, or the
power required by the application according to the indications contained in the section (refer to the “Thermal
power” paragraph).
B.
Maximum torque
S Series
/
ATEX
/
IEC
TECHNICAL CATALOGUE
1.3 PRODUCT SELECTION
8