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Maintenance
NOTE
Spherical roller thrust bearings are spring loaded and
require a positive down thrust in addition to the rotor
weight to prevent up thrust on lower guide bearing
(See Figure 8).
Measure axial end play by jacking the shaft upward
while measuring the shaft axial movement with a dial
indicator attached to the upper bearing housing. For
motors with spring loaded spherical roller bearings,
the rotor end play will most often be downward. The
downward rotor displacement can be measured by
jacking the rotor downward using a hydraulic jack
placed between the top of the shaft and a beam
fastened to the upper bearing housing.
When jacking the rotor upward or downward
CAUTION should be taken not to exert excessive
force on the rotor as this may damage the end cap or
add structural deflections to the axial end play
measurement.
Adjust the end play using shims of proper design and
thickness under the end cap of the lower bearing in
motors with shrink fit thrust block design or by
adjusting the thrust block travel by loosening the nut
above the thrust block in the slip fit thrust block
design. It is a good practice to check the end play
after final adjustments.
Kingsbury-type Bearings
Thrust Bearing
Principle elements of the Kingsbury-type thrust
bearing are the rotating thrust runner and the
stationary pivotal thrust shoes (See Figure 7) The
runner is the highly polished bottom surface of the
thrust block and receives the thrust load through a
massive nut above the thrust block threaded on the
top end of the shaft. The pivotal thrust shoes are
faced with tin-hard Babbitt and machined to form an
accurate surface plate.
During operation, the thrust bearing revolves in an oil
bath which covers the bearing. Each shoe is free to
tilt slightly in any direction and sets itself by pivoting
at a minute angle causing a wedge-shaped film of oil
to form between the shoe and the runner. An end
play of 0.012 – 0.017 inches is preset at the factory
by shims between the thrust plate and the upper
guide (upthrust) bearing.
Upper Guide (Upthrust) Bearing
The upper guide (upthrust) bearing with a Kingsbury-
type bearing is located just above the rotating thrust
runner and is mounted in the stationary thrust plate.
This bearing is babbitted on the inside diameter
surface which bears on a ground and polished
surface of the thrust block. This bearing is also
babbitted on the bottom surface which bears on the
ground and polished surface of the thrust block. This
bearing locates the shaft in the radial direction and
transfers upthrust from the shaft through the thrust
block to the thrust plate. The thrust bearing and the
lower half of the upper guide bearing are immersed in
oil. The upper portion of the upper guide bearing
receives oil through radial holes in the thrust block
and discharges oil through radial and helical grooves
in the guide bearing surface. The discharged oil is
deflected through the oil cooler tubes by an oil baffle
mounted on the bottom of the thrust plate.
Lower Guide Bearing
The function of the lower guide bearing with a
Kingsbury-type bearing is to provide radial location of
the shaft with no thrust or end play limit. This bearing
may be one of three types – grease-lubricated ball
bearing, oil-lubricated ball bearing, or oil-lubricated
sleeve bearing (See Figures 9, 10 and 11).
Oil Operating Temperature
The normal temperature of the oil should be about
50
°
C to 70
°
C. The maximum safe temperature for
most bearings is 95
°
C to 100
°
C at the babbitt.
NOTE
Bearing temperature should not be judged by feeling
the bearing with the hand; temperature should be
measured by a thermometer or thermocouple placed
as close to the babbitt as possible.
The thrust bearing is cooled by water passing
through the heat exchanging copper tubes in the
bearing oil bath. The rate of water flow is dependent
on water temperature, volume of oil, and the total
friction losses (load) of the bearing. Supply the
necessary amount of water required to cool the
bearing, but not to exceed the amount specified on
the outline drawing.
Содержание CAZBHS
Страница 25: ... 24 Maintenance UPPER BEARING ARRANGEMENTS Figure 7 Figure 8 ...
Страница 26: ... 25 Maintenance LOWER BEARING ARRANGEMENTS Figure 9 Figure 10 Figure 11 ...
Страница 27: ... 26 Maintenance Self Release Coupling Arrangement At Top Of Motor Figure 12 ...
Страница 30: ... 29 Spare Parts Figure 16 ...
Страница 31: ... 30 Spare Parts Figure 17 ...
Страница 32: ... 31 Spare Parts Figure 18 ...
Страница 33: ... 32 Spare Parts Figure 19 ...
Страница 34: ... 33 Spare Parts Figure 20 ...
