Specifications

AM - 28 Asynchronous Motors Ver. 0002
AM.12 BEARINGS
The special bearings are the ball-bearing type, suitable for high speeds and lubricated with
special greases resistant to high rotation and temperature conditions.
The maximum theoretical life of the bearings is calculated in about 20,000 hours of continuous
operation at 1500 rpm approx. For higher average rotation speeds, the life of the bearings
varies as follows:
30 - 50% of n
max .
– about 16,000 hours
50 - 60% of n
max .
– about 12,000 hours
60 - 70% of n
max .
– about 8,000 hours
The data and the operating hours are calculated for normal operating conditions, without
vibrations and with temperatures within the limits imposed by the bearing manufacturers.
The speed n
max
is to intended as the maximum limit of rotation and not as continuous
operating speed, which is limited to about 70% of n
max
.
Notes:
On the non drive side, a rigid radial ball bearing is always installed.
For coupling with a pulley, the radial load acting on the shaft can be calculated using the
following formula:
Fr = Radial load in [N] Pn = Nominal power in [kW]
Nn = Nominal speed in [rpm] D = Diameter of pulley in [mm]
Pp = Weight of pulley in [N] K = 1 - 1.5 for cog belts
2 - 2.5 for V-belts
3 - 4 for flat belts
Caution: It is advisable, at the first start up of the motor, to carry out the breaking-in of the
bearings. Increase progressively the velocity of the motor from 0 to about 70% of n
max
in about
20 min. Never operate the motor at the maximum speed for long periods of time.
Watch the temperature and possible abnormal noises.
During the first minutes of operation, a higher than normal noise can be heard, due to the non
uniform distribution of the grease inside the bearing. The noise should return back to normal at
the end of the break-in.
As for special bearings (high speed for spindles), the break-in operation is a must.
During the break-in, the fan must be in operation. Clamp securely the key before starting the
motor.
Any gasket or seal rings installed as protection for the bearing can be removed only if not
deemed necessary to the purpose (particularly clean environment, additional external
mechanical protections). By doing so, the friction and the operating temperature will decrease.
Fr
Pn K
DNn
Pp=⋅⋅
⋅
⋅
±19 5 10
6
.