Nord Catalogue - Nottingham Electrical Transmissions

SELECTION PROCEDURES
Criteria for selection of the gearboxes are:
1) mechanical power - service factor shown in the
tables in catalog
2) thermal power limit - depending on
a) mounting position e.g. V5/V6/V (oil quantity)
b) the ratio i 3h
(thermal load)
Please contact application engineering for gearbox types marked * .
Higher powers possible with short term operation. For continuous operation
special features (optimal oil-level, oil-cooler etc.) may be required, please
consult factory.
Each application requires either the calculation or the measurement of the
required motor power. Base the motor selection on the above power
requirement. Intermittent shock loading should not be considered for motor
power determination.
On the other hand, it is important to consider the type of loading when
selecting the gearbox size. The service factor fB can be determined by taking
into account the factor of inertia maf as well as cycles/ hour and the operating
time.
Type of loading for gearboxes and geared motors:
A Light conveyor screws, fans, assembly lines, light conveyor belts, small
agitators, elevators, cleaning machines, filling machines, inspection
machines, belt conveyors.
Service factor fB
Operating time
hours / day
Solid input shaft and NEMA C-face adapters
The powers listed refer to W - Types. For NEMA C-face the standard powers
refer to frame sizes by industry standards.
C-face adapter couplings are not fail - safe. For hoist- and lift- applications
please contact factory.
OVERHUNG LOADS
The following table lists the overhung loads for foot and flange mounted
units. Loads are calculated as applied to the midpoint of the shaft. The listed
values are based on service factor fB = 1. For shock loading applications the
service factor has to be taken into consideration.
The permissible overhung load values listed are based on the least favorable
loading direction. For higher overhung load values please contact the factory
with the exact loading direction and required life expectancy.
If there are transmission elements connected to the output shaft a factor fz
has to be taken into account when calculating the applied overhung load.
EXPLANATORY NOTES
Cycles / hour
B Coilers, feed-mechanism drivers for wood- working machines,
dumbwaiters, balancing machines, thread cutting machines, mediumsized
agitators and mixers, heavy conveyor belts, winches, sliding doors,
manure scrapers, packing machines, concrete mixers, crane traveling
mechanisms, mills, bending machines, gear pumps.
C Heavy mixers, shears, presses, centrifuges, rolling stands, heavy winches
and lifts, grinding mills, stone crushers, bucket elevators, punching
machines, hammer mills, eccentric presses, folding machines, roller
tables, tumbing barrels, vibrators, shredders.
Other machines should be associated to one of the three groups, depending
on the type of load they represent.
The service factor is the quotient of maximum output torque and nominal
output torque where nominal output torque is defined as the quotient of power
and output speed.
Output
torque T2
63025 P n2
[Lb - in]
P [HP]
n2 [RPM]
Service
factor fB
T2
max
T2
To select the correct gearbox the service factor taken from the diagram must
be less than or at maximum equal the service factor which is listed in the
selection charts at the appropriate speed. The listed overhung load values are
based on a service factor fB =1.
TYPE OF LOADING: MASS ACCELERATION FACTOR:
A uniform maf 0.25
B moderate shock maf 3.00
C heavy shock maf 10.00
maf
I ex.red.
I Mot.
Iex.red. = all external inertia moments corrected to motor input
I Mot = moment of inertia of the motor
The effective overhung load at the gearbox shaft will be determined as
follows:
FQ
exis.
2 T2
do
fz FQperm
FQ exis. Existing overhung load at the gearbox shaft [Lb]
FQ perm perm. overhung load values from selection table [Lb]
T2 output torque of gearbox [Lb-in]
fz coefficient from table
do dia of overhung load member [in]
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