ABB
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ABB | Motors and Generators
| Synchronous motors
High quality sleeve bearings for trouble-free operation
ABB synchronous motors use quality sleeve bearings
that withstand high levels of vibration and offer excellent
performance.
The bearings provide the same high levels
of reliability under static as well as dynamic (radial and
axial) loads. Their excellent heat transfer capability makes
them equally suitable for low and high speed applications.
The choice of bearing arrangement and type is based
on the application, radial and axial loads, rotation speed,
coupling type, and customer preferences. Operating
conditions such as ambient temperature, air cleanliness,
vibration levels and shocks affecting the bearings are
also taken into account.
End-shield mounted bearings are always used in higher
speed (four and six pole) motors. Pedestal mounted bearings
are generally used for the largest frame sizes. Motors with
pedestal bearings are as easy to mount and align as those
with end-shield mounted bearings. The motors are normally
delivered ready assembled and require no further assembly
on site. Separate pedestal bearing motors are often
mounted on a common base frame.
Sleeve bearings last as long as the expected life of
the motor, provided that the operating conditions and
maintenance intervals are as specified.
The bearing housing is designed to permit easy access
for inspection and maintenance. The bearings are insulated
from the motor frame to eliminate circulating currents in
the shaft, and the shaft can be earthed. The bearings are
sealed against oil leakage with labyrinth seals. Sleeve
bearings are designed to be insensitive to misalignment
and to permit large axial play.
Lubrication
In some cases the bearings are self-lubricated by means
of an oil ring, which picks up the lubricating oil and transfers
it directly to the shaft, forming an independent and highly
reliable lubrication system.
In applications involving large loads, high speeds, high
ambient temperature or where the motor is mounted in an
inclined position, an external oil cooling and circulation system
may be necessary, unless the oil is supplied direct from
the lubrication system of the driven equipment. In certain
applications which run at slow speeds, a jack-up system
may be necessary for starting.
Hydrostatic jacking oil systems are available for low-speed
applications and, in specific situations, for use during motor
start-up /shut down.
Flange mounted sleeve bearing
Pedestal mounted sleeve bearing