low-voltage

Squirrel-cage motors
Technical information
Mechanical design
■ Bearings
Bearing life (nominal rated
life)
The nominal bearing life is
specified by standard calculation
methods (DIN ISO 281) and
is achieved or exceeded by
90 % of bearings when operated
in accordance with catalog
specifications.
If the operating conditions are
below average, a bearing life of
100,000 (L h10 ) hours can be
achieved.
The bearing life essentially depends
on the size of the bearing,
the load, the operating conditions,
the speed, and the relubrication
interval.
Bearing system
The nominal bearing life of motors
with horizontal type of construction
is at least 40,000 hours
if there is no additional axial
loading at the output coupling;
with the maximum permitted
loads it is at least 20,000 hours.
This is provided that the motor is
operated at 50 Hz. The nominal
bearing life is reduced for converter-fed
operation with higher
frequencies.
In the basic design of the bearings
system, the floating bearing
is at the drive end (DE) and
the located bearing (axially
fixed from frame size 160) at the
non-drive end (NDE). The located
bearings can also be fitted to
the drive end (DE) on request,
(Fig. 3 Page 2/34).
Order Code K94
The bearings system is axially
pre-loaded with a spring which
ensures that the motor runs
smoothly and free of clearance.
This does not apply to designs
with parallel roller bearings. The
bearings of these motors must
always be operated with sufficient
radial force (do not operate
motor in test bay without additional
axial loading).
The motors of the 1LA6, 1LA7,
1LA9, and 1MA7 series up to
and including frame size 132
are fitted with a floating bearings
system (Fig. 1 Page 2/34).
An additional axially secured
bearing at the non-drive end
(NDE) with a retaining ring can
be delivered up to frame size
132 on request (Fig. 2
Page 2/34).
Order Code L04
From frame size 160, all bearings
are axially fixed (Fig. 2, 4,
and 5, Page 2/34).
If high cantilever forces are exerted
at the drive end, e.g. owing
to a belt transmission, the
motors can be fitted with
strengthened bearings on request.
Order Code K20
The 1LG4/6 motors with frame
sizes 180 to 250 and with frame
size 315, 2-pole, are available
with strengthened deep groove
ball bearings on both sides
(dimension series 03).
Order Code K36
See pages 2/32 and 2/33 for a
selection of bearings for high
cantilever forces; maximum
loadings on Page 2/37.
Prelubricated
For prelubricated bearings, the
grease life is tailored to the
bearing life. However, the motor
must be operated according to
catalogue specifications.
Standard motors with a frame
size of up to and including 250
are prelubricated.
Grease life and regreasing intervals
Life lubrication 1 )
Type series Size Number of
poles
Regreasable
The bearing life of regreasable
motors can be increased by observing
specified relubrication
intervals; this can also compensate
for other factors such as
temperatures, ingress of liquids,
speed, bearing size, and
mechanical load.
From frame size 280, the bearings
can be regreased with a
flat-type grease nipple M10 x 1
in accordance with DIN 3404.
Regreasable bearings can be
fitted in motors with frame sizes
100 to 250.
Order Code K40
Grease life
up to CT 40 °C 2 )
all 56 to 250 2 to 8 20,000 h or 40,000 h 3 )
Regreasing 2 )
Type series Size Number of
poles
1LA6 100 to 160 2 to 8 8000 h
1LA5
100 to 225 2 to 8 8000 h
1LA7
1LA9
1LA8 315 to 400 2 4000 h
4 to 8 6000 h
450 2 3000 h
4 to 8 6000 h
1MA6 100 to 200 2 to 8 8000 h
225 to 280 2 4000 h
4 to 8 8000 h
315 2 3000 h
4 to 8 6000 h
1MA7 100 to 160 2 to 8 8000 h
1MJ6
1MJ7
1MJ8
1MJ1
180 to 200 2 to 8 8000 h
225 to 280 2 4000 h
4 to 8 8000 h
315 2 3000 h
4 to 8 6000 h
355 to 450 2 and 4 2000 h
6 and 8 4000 h
180 to 280 2 4000 h
4 to 8 8000 h
315 2 3000 h
4 to 8 6000 h
Regreasing interval
up to CT 40 °C 2 )
2
1LG4
1LG6
1) For special uses and special
greases, please ask about grease
life and regreasing interval.
2) If the coolant temperature is increased
by 10 K, the greasing life
and regreasing interval is halved.
3) 40,000 h applies to clutch abrasion
for horizontally installed motors
without additional axial loads.
Siemens M 11 · 2003/2004 2/29